PHYSIOLOGY NOTES - Dr. SUDHADEVI SADANANDAN
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Oct 23, 2025
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About This Presentation
Applied Physiology Notes – For B.Sc Nursing (1st Semester), GNM (1st Year) & Applied Science Students -Prepared by Dr. Sudhadevi Sadanandan
Principal, Rajkali Institute of Nursing and Paramedical Sciences, Raebareli
(Former Deputy Registrar, Uttar Pradesh Nurses and Midwives Council)
Concep...
Slide Content
PHYSIOLOGY OF HEARING – 28 points
?????? A. Introduction – 1 Point
1. Definition:
Hearing is the process where sound waves are changed into nerve impulses, which the brain
interprets as sound.
?????? B. Flow Chart 1 – Basic Hearing Pathway (9 Points)
2. Pinna: Collects sound waves from the surroundings.
3. Auditory Canal: Directs the sound waves toward the eardrum.
4. Tympanic Membrane (Eardrum): Vibrates when sound hits it.
5. Ear Ossicles: Three small bones—malleus, incus, and stapes—amplify the vibration.
6. Cochlea: A fluid-filled spiral structure that receives these vibrations.
7. Hair Cells: Sense the fluid movement and create electrical signals.
8. Auditory Nerve: Carries these electrical signals to the brain.
9. Auditory Cortex: Brain area that interprets these signals.
10. Sense of Hearing: We become aware of the sound.
?????? C. Flow Chart 2 – Detailed Physiology (9 Points)
11. Sound Waves: Start from any vibrating object and enter the ear.
12. Vibration of Tympanic Membrane: The eardrum vibrates exactly with the sound frequency.
13. Vibration of Middle Ear Bones: Ossicles move, increasing force of vibration.
14. Vibration of Oval Window: The stapes pushes on the oval window of the cochlea.
15. Fluid Movement within Cochlea: Creates pressure waves in the cochlear fluid.
16. Vibration of Basilar Membrane: Pressure waves move the membrane at specific spots for
each frequency.
17. Bending of Hair Cells (Organ of Corti): Hair cells bend against the tectorial membrane,
producing receptor potentials.
18. Action Potentials in Auditory Nerve: These receptor potentials trigger impulses in nerve
fibers.
19. Auditory Cortex – Interpretation: The brain recognizes pitch, loudness, and meaning of the
sound.
?????? D. Key Points of Flow Chart – 4 Points
20. Outer Ear – Sound Collection: Works like a funnel to gather sound.
21. Middle Ear – Amplification: Strengthens the vibration for clear transmission.
?????? A. Introduction – 1 Point
1. Definition:
Hearing is the process where sound waves are changed into nerve impulses, which the brain
interprets as sound.
?????? B. Flow Chart 1 – Basic Hearing Pathway (9 Points)
2. Pinna: Collects sound waves from the surroundings.
3. Auditory Canal: Directs the sound waves toward the eardrum.
4. Tympanic Membrane (Eardrum): Vibrates when sound hits it.
5. Ear Ossicles: Three small bones—malleus, incus, and stapes—amplify the vibration.
6. Cochlea: A fluid-filled spiral structure that receives these vibrations.
7. Hair Cells: Sense the fluid movement and create electrical signals.
8. Auditory Nerve: Carries these electrical signals to the brain.
9. Auditory Cortex: Brain area that interprets these signals.
10. Sense of Hearing: We become aware of the sound.
?????? C. Flow Chart 2 – Detailed Physiology (9 Points)
11. Sound Waves: Start from any vibrating object and enter the ear.
12. Vibration of Tympanic Membrane: The eardrum vibrates exactly with the sound frequency.
13. Vibration of Middle Ear Bones: Ossicles move, increasing force of vibration.
14. Vibration of Oval Window: The stapes pushes on the oval window of the cochlea.
15. Fluid Movement within Cochlea: Creates pressure waves in the cochlear fluid.
16. Vibration of Basilar Membrane: Pressure waves move the membrane at specific spots for
each frequency.
17. Bending of Hair Cells (Organ of Corti): Hair cells bend against the tectorial membrane,
producing receptor potentials.
18. Action Potentials in Auditory Nerve: These receptor potentials trigger impulses in nerve
fibers.
19. Auditory Cortex – Interpretation: The brain recognizes pitch, loudness, and meaning of the
sound.
?????? D. Key Points of Flow Chart – 4 Points
20. Outer Ear – Sound Collection: Works like a funnel to gather sound.
21. Middle Ear – Amplification: Strengthens the vibration for clear transmission.
22. Inner Ear – Transduction: Converts mechanical energy into electrical impulses.
23. Auditory Cortex – Interpretation: Makes sense of what we hear.
?????? E. Additional Notes – 5 Points
24. Speed of Sound: Travels through air at about 332 meters per second.
25. Hearing Range: Humans hear between 20 Hz and 20,000 Hz.
26. Hair Cell Function: Convert vibration (mechanical) to electrical form.
27. Basilar Membrane Response: Different regions detect high or low frequencies.
28. Whole Ear Coordination: Outer, middle, and inner ear work together for smooth hearing.
?????? Total = 28 Teaching Points
Physiology of Taste
23. Auditory Cortex – Interpretation: Makes sense of what we hear.
?????? E. Additional Notes – 5 Points
24. Speed of Sound: Travels through air at about 332 meters per second.
25. Hearing Range: Humans hear between 20 Hz and 20,000 Hz.
26. Hair Cell Function: Convert vibration (mechanical) to electrical form.
27. Basilar Membrane Response: Different regions detect high or low frequencies.
28. Whole Ear Coordination: Outer, middle, and inner ear work together for smooth hearing.
?????? Total = 28 Teaching Points
Physiology of Taste
1. Introduction
Taste is one of the five important special senses of the human body.
It helps a person to recognize and enjoy food and also to identify harmful or spoiled substances.
Taste plays a vital role in eating habits, digestion, and maintaining good nutrition.
2. Definition
Taste is the sensation produced when chemical substances in food come in contact with the taste
buds on the tongue and are interpreted by the brain as sweet, sour, salty, bitter, or Umami (meaty
taste).
3. Location of Taste Buds
Taste buds are small sensory structures found mainly on the tongue.
They are located inside small projections called papillae — fungi form, foliate, and
circumvallated papillae.
A few taste buds are also present in the soft palate, pharynx, and epiglottis.
Each taste bud contains 50–100 taste receptor cells.
4. Physiology of Taste (Process of Taste Perception)
1. When food enters the mouth, it mixes with saliva.
2. The food molecules dissolve in saliva and come in contact with the taste buds.
3. These chemical substances stimulate the taste receptor cells.
4. The stimulation produces small electrical impulses.
5. These impulses are carried to the brain through three cranial nerves:
Facial nerve (VII) – from the front part of the tongue.
Gloss pharyngeal nerve (IX) – from the back part of the tongue.
Vagus nerve (X) – from the throat and epiglottis.
6. All the signals first reach the medulla oblongata in the brainstem.
7. From the brainstem, impulses pass to the thalamus, which acts as a relay center.
8. From the thalamus, impulses reach the gustatory cortex of the cerebrum.
9. The brain then recognizes and identifies the taste — sweet, sour, salty, bitter, or Umami.
5. Basic Tastes
There are five basic tastes recognized by the taste buds:
1. Sweet – caused by sugars and sweet substances.
2. Sour – caused by acids such as lemon and vinegar.
Taste is one of the five important special senses of the human body.
It helps a person to recognize and enjoy food and also to identify harmful or spoiled substances.
Taste plays a vital role in eating habits, digestion, and maintaining good nutrition.
2. Definition
Taste is the sensation produced when chemical substances in food come in contact with the taste
buds on the tongue and are interpreted by the brain as sweet, sour, salty, bitter, or Umami (meaty
taste).
3. Location of Taste Buds
Taste buds are small sensory structures found mainly on the tongue.
They are located inside small projections called papillae — fungi form, foliate, and
circumvallated papillae.
A few taste buds are also present in the soft palate, pharynx, and epiglottis.
Each taste bud contains 50–100 taste receptor cells.
4. Physiology of Taste (Process of Taste Perception)
1. When food enters the mouth, it mixes with saliva.
2. The food molecules dissolve in saliva and come in contact with the taste buds.
3. These chemical substances stimulate the taste receptor cells.
4. The stimulation produces small electrical impulses.
5. These impulses are carried to the brain through three cranial nerves:
Facial nerve (VII) – from the front part of the tongue.
Gloss pharyngeal nerve (IX) – from the back part of the tongue.
Vagus nerve (X) – from the throat and epiglottis.
6. All the signals first reach the medulla oblongata in the brainstem.
7. From the brainstem, impulses pass to the thalamus, which acts as a relay center.
8. From the thalamus, impulses reach the gustatory cortex of the cerebrum.
9. The brain then recognizes and identifies the taste — sweet, sour, salty, bitter, or Umami.
5. Basic Tastes
There are five basic tastes recognized by the taste buds:
1. Sweet – caused by sugars and sweet substances.
2. Sour – caused by acids such as lemon and vinegar.
3. Salty – caused by salts and sodium compounds.
4. Bitter – caused by alkaloids and some medicines.
5. Umami – caused by amino acids such as glutamate (found in cheese, soup, and meat).
6. Combination with Other Senses
Taste works together with smell, temperature, and texture to produce the overall flavor of food.
When the sense of smell is reduced (for example, during a cold), food tastes less flavorful.
7. Adaptation
When a particular taste is experienced continuously, the taste buds become less sensitive.
This is called taste adaptation.
Example: After eating several sweets, the next one tastes less sweet.
8. Effect of Age
Children have more taste buds, so their taste sensation is stronger.
Elderly people have fewer taste buds; hence, taste sensation becomes weaker, especially for
sweet and salty tastes.
9. Functions of Taste
1. Helps to identify and enjoy food.
2. Protects the body from harmful or spoiled food.
3. Stimulates secretion of saliva and digestive juices.
4. Improves appetite and satisfaction during eating.
5. Helps maintain a balanced diet by recognizing different food types.
10. Summary Flow
Food → Mixes with Saliva → Stimulates Taste Buds →
Cranial Nerves (VII, IX, X) → Medulla Oblongata →
Thalamus → Gustatory Cortex → Taste Perception → Flavor Formation
Physiology of Oogenesis
4. Bitter – caused by alkaloids and some medicines.
5. Umami – caused by amino acids such as glutamate (found in cheese, soup, and meat).
6. Combination with Other Senses
Taste works together with smell, temperature, and texture to produce the overall flavor of food.
When the sense of smell is reduced (for example, during a cold), food tastes less flavorful.
7. Adaptation
When a particular taste is experienced continuously, the taste buds become less sensitive.
This is called taste adaptation.
Example: After eating several sweets, the next one tastes less sweet.
8. Effect of Age
Children have more taste buds, so their taste sensation is stronger.
Elderly people have fewer taste buds; hence, taste sensation becomes weaker, especially for
sweet and salty tastes.
9. Functions of Taste
1. Helps to identify and enjoy food.
2. Protects the body from harmful or spoiled food.
3. Stimulates secretion of saliva and digestive juices.
4. Improves appetite and satisfaction during eating.
5. Helps maintain a balanced diet by recognizing different food types.
10. Summary Flow
Food → Mixes with Saliva → Stimulates Taste Buds →
Cranial Nerves (VII, IX, X) → Medulla Oblongata →
Thalamus → Gustatory Cortex → Taste Perception → Flavor Formation
Physiology of Oogenesis
Definition & Site
1. Oogenesis = process of formation and maturation of the female gamete (ovum).
2. It begins before birth in the fetal ovary.
3. Takes place in the ovary, mainly in the outer cortical (germinal) epithelium.
4. Each developing ovum lies inside a small sac called a follicle.
5. The purpose is to produce one mature ovum capable of fertilization each cycle.
Phases of Oogenesis
6. Oogenesis occurs in three main phases →
(1) Multiplication phase
(2) Growth phase (3) Maturation phase.
1
️ Multiplication Phase (Fetal Life)
7. In the fetus, primordial germ cells multiply by mitosis to form oogonia (2n).
8. Some oogonia enter meiosis I → become primary oocytes (2n).
9. Each primary oocytes gets surrounded by a layer of flat follicle cells → primordial follicle.
10. All primary oocytes pause in prophase I (dictyate stage).
11. At birth ≈ 1–2 million primary oocytes present in each ovary.
12. During childhood, many degenerate naturally (artesian).
13. By puberty ≈ 3–4 lakh primary oocytes remain.
Growth Phase (After Puberty)
2️2️⃣
14. At puberty, GnRH from hypothalamus stimulates pituitary → releases FSH and LH.
15. FSH stimulates a group of primordial follicles to grow each month.
16. The primary oocytes enlarges in size.
17. Follicle cells multiply → granulose layers form.
18. A transparent cover (zona pellucid) appears around the oocytes.
19. Fluid collects → antrum forms → follicle becomes a Gratian follicle.
20. Growing follicle secretes estrogen, which thickens the endometrial and suppresses FSH.
Maturation Phase
3️3️⃣
21. Mid-cycle, high estrogen causes an LH surge from the pituitary.
22. LH surge stimulates primary oocytes to complete meiosis I.
23. Unequal division → secondary oocytes (n) + first polar body (n).
24. Secondary oocytes immediately begins meiosis II → stops at metaphase II.
1. Oogenesis = process of formation and maturation of the female gamete (ovum).
2. It begins before birth in the fetal ovary.
3. Takes place in the ovary, mainly in the outer cortical (germinal) epithelium.
4. Each developing ovum lies inside a small sac called a follicle.
5. The purpose is to produce one mature ovum capable of fertilization each cycle.
Phases of Oogenesis
6. Oogenesis occurs in three main phases →
(1) Multiplication phase
(2) Growth phase (3) Maturation phase.
1
️ Multiplication Phase (Fetal Life)
7. In the fetus, primordial germ cells multiply by mitosis to form oogonia (2n).
8. Some oogonia enter meiosis I → become primary oocytes (2n).
9. Each primary oocytes gets surrounded by a layer of flat follicle cells → primordial follicle.
10. All primary oocytes pause in prophase I (dictyate stage).
11. At birth ≈ 1–2 million primary oocytes present in each ovary.
12. During childhood, many degenerate naturally (artesian).
13. By puberty ≈ 3–4 lakh primary oocytes remain.
Growth Phase (After Puberty)
2️2️⃣
14. At puberty, GnRH from hypothalamus stimulates pituitary → releases FSH and LH.
15. FSH stimulates a group of primordial follicles to grow each month.
16. The primary oocytes enlarges in size.
17. Follicle cells multiply → granulose layers form.
18. A transparent cover (zona pellucid) appears around the oocytes.
19. Fluid collects → antrum forms → follicle becomes a Gratian follicle.
20. Growing follicle secretes estrogen, which thickens the endometrial and suppresses FSH.
Maturation Phase
3️3️⃣
21. Mid-cycle, high estrogen causes an LH surge from the pituitary.
22. LH surge stimulates primary oocytes to complete meiosis I.
23. Unequal division → secondary oocytes (n) + first polar body (n).
24. Secondary oocytes immediately begins meiosis II → stops at metaphase II.
25. Now ready for ovulation (around day 14 of a 28-day cycle).
26. The mature follicle ruptures → secondary oocytes released into fallopian tube.
27. Ruptured follicle forms corpus luteum, which secretes progesterone to maintain the uterine lining.
Fate of the Secondary Oocyte
A. If Fertilization Does Not Occur
28. Secondary oocytes survives 12–24 hours then degenerates.
29. Corpus luteum → shrinks → corpus albicans.
30. Progesterone and estrogen levels fall.
31. Endometrial breaks down → menstruation.
32. Next cycle starts under new FSH influence.
B. If Fertilization Occurs
33. Sperm enters secondary oocytes → completes meiosis II.
34. Forms ovum (n) + second polar body (n).
35. Sperm nucleus + ovum nucleus fuse → zygote (2n).
36. Embryo secretes hCG → keeps corpus luteum active for progesterone support.
Hormonal Regulation
37. FSH – Stimulates follicle growth and oocytes maturation.
38. LH – Triggers ovulation and completion of meiosis I.
39. Estrogen – Builds endometrial and causes LH surge.
40. Progesterone – Maintains uterus after ovulation for implantation.
Key Summary
Process starts before birth and completes only after fertilization.
One primary oocytes → one ovum + three polar bodies.
Total ovulations in lifetime ≈ 400–500.
Oocyte lifespan ≈ 12–24 hours after ovulation.
Flow Chart
Oogonia (2n) → Primary Oocyte (2n) → (Meiosis I) → Secondary Oocyte (n) + 1st Polar Body
→ (Meiosis II + Fertilization) → Ovum (n) + 2nd Polar Body → Zygote (2n)
Spermatogenesis Notes
1. Definition
26. The mature follicle ruptures → secondary oocytes released into fallopian tube.
27. Ruptured follicle forms corpus luteum, which secretes progesterone to maintain the uterine lining.
Fate of the Secondary Oocyte
A. If Fertilization Does Not Occur
28. Secondary oocytes survives 12–24 hours then degenerates.
29. Corpus luteum → shrinks → corpus albicans.
30. Progesterone and estrogen levels fall.
31. Endometrial breaks down → menstruation.
32. Next cycle starts under new FSH influence.
B. If Fertilization Occurs
33. Sperm enters secondary oocytes → completes meiosis II.
34. Forms ovum (n) + second polar body (n).
35. Sperm nucleus + ovum nucleus fuse → zygote (2n).
36. Embryo secretes hCG → keeps corpus luteum active for progesterone support.
Hormonal Regulation
37. FSH – Stimulates follicle growth and oocytes maturation.
38. LH – Triggers ovulation and completion of meiosis I.
39. Estrogen – Builds endometrial and causes LH surge.
40. Progesterone – Maintains uterus after ovulation for implantation.
Key Summary
Process starts before birth and completes only after fertilization.
One primary oocytes → one ovum + three polar bodies.
Total ovulations in lifetime ≈ 400–500.
Oocyte lifespan ≈ 12–24 hours after ovulation.
Flow Chart
Oogonia (2n) → Primary Oocyte (2n) → (Meiosis I) → Secondary Oocyte (n) + 1st Polar Body
→ (Meiosis II + Fertilization) → Ovum (n) + 2nd Polar Body → Zygote (2n)
Spermatogenesis Notes
1. Definition
Spermatogenesis is the process of formation of spermatozoa (male gametes) from spermatogonia
inside the somniferous tubules of the testes.
2. Duration & Site
Takes about 64–74 days.
Occurs in somniferous tubules; supported by Sertoli cells.
3. Phases of Spermatogenesis
1. Multiplication (Mitosis): Spermatogonia divide repeatedly; some remain stem cells, others
become primary spermatocytes.
2. Growth: Primary spermatocytes enlarge and prepare for meiosis.
3. Maturation (Meiosis):
Primary spermatocytes (2n) → Meiosis I → 2 Secondary spermatocytes (n).
Each secondary spermatocytes → Meiosis II → 2 Spermatids (n).
Total: 1 primary spermatocytes → 4 Spermatids.
4. Spermatogenesis: Spermatids transform into spermatozoa (tail forms, macrodome develops,
nucleus condenses).
5. Spermiation: Mature spermatozoa released into lumen of somniferous tubules.
4. Hormonal Control of Spermatogenesis
GnRH (Gonadotropin-Releasing Hormone):
Secreted by hypothalamus.
Stimulates anterior pituitary.
FSH (Follicle Stimulating Hormone):
Secreted by anterior pituitary.
Acts on Sertoli cells → supports spermatogenesis & releases Inhibin.
LH (Luteinizing Hormone):
Secreted by anterior pituitary.
Acts on Leydig cells → secretes testosterone.
Testosterone:
Secreted by Leydig cells.
Essential for maturation of sperm and development of male secondary sexual characters.
Inhibin:
Secreted by Sertoli cells.
inside the somniferous tubules of the testes.
2. Duration & Site
Takes about 64–74 days.
Occurs in somniferous tubules; supported by Sertoli cells.
3. Phases of Spermatogenesis
1. Multiplication (Mitosis): Spermatogonia divide repeatedly; some remain stem cells, others
become primary spermatocytes.
2. Growth: Primary spermatocytes enlarge and prepare for meiosis.
3. Maturation (Meiosis):
Primary spermatocytes (2n) → Meiosis I → 2 Secondary spermatocytes (n).
Each secondary spermatocytes → Meiosis II → 2 Spermatids (n).
Total: 1 primary spermatocytes → 4 Spermatids.
4. Spermatogenesis: Spermatids transform into spermatozoa (tail forms, macrodome develops,
nucleus condenses).
5. Spermiation: Mature spermatozoa released into lumen of somniferous tubules.
4. Hormonal Control of Spermatogenesis
GnRH (Gonadotropin-Releasing Hormone):
Secreted by hypothalamus.
Stimulates anterior pituitary.
FSH (Follicle Stimulating Hormone):
Secreted by anterior pituitary.
Acts on Sertoli cells → supports spermatogenesis & releases Inhibin.
LH (Luteinizing Hormone):
Secreted by anterior pituitary.
Acts on Leydig cells → secretes testosterone.
Testosterone:
Secreted by Leydig cells.
Essential for maturation of sperm and development of male secondary sexual characters.
Inhibin:
Secreted by Sertoli cells.
Provides negative feedback to anterior pituitary → reduces FSH secretion.
5. Significance of Spermatogenesis
Begins at puberty and continues lifelong.
Produces about 200–300 million sperms daily.
Needs 2–3°C lower temperature than body → maintained by scrotum.
Ensures continuous production of male gametes for fertilization.
Controlled by the hypothalamic–pituitary–testicular axis.
6. Conclusion
Spermatogenesis is a continuous, hormone-regulated process that transforms spermatogonia into
mature spermatozoa, ensuring male fertility.
Cardiac Cycle
1 Introduction
5. Significance of Spermatogenesis
Begins at puberty and continues lifelong.
Produces about 200–300 million sperms daily.
Needs 2–3°C lower temperature than body → maintained by scrotum.
Ensures continuous production of male gametes for fertilization.
Controlled by the hypothalamic–pituitary–testicular axis.
6. Conclusion
Spermatogenesis is a continuous, hormone-regulated process that transforms spermatogonia into
mature spermatozoa, ensuring male fertility.
Cardiac Cycle
1 Introduction
1. The heart works as a muscular pump that sends blood to all parts of the body.
2. With every heartbeat, a series of events take place inside the heart — this is called the cardiac
cycle.
3. It includes the contraction (systole) and relaxation (diastole) of the atria and ventricles.
4. The cardiac cycle helps maintain a continuous flow of blood and keeps oxygen supply
constant.
Definition
2️2️⃣
1. The cardiac cycle is the complete sequence of events that occur in the heart during one
heartbeat.
2. It includes atrial contraction, ventricular contraction, and relaxation of both chambers.
3. One cardiac cycle lasts about 0.8 seconds in a healthy adult.
Duration
3️3️⃣
1. The heart beats about 72 times per minute.
2. Each cardiac cycle takes 0.8 seconds.
3. The duration of different phases is as follows:
Atrial systole: 0.1 second
Ventricular systole: 0.3 second
Complete diastole: 0.4 second
Phases of the Cardiac Cycle
4️4️⃣
A. Atrial Diastole
1. Both atria are relaxed and receive blood from the veins.
2. The right atrium receives deoxygenated blood from the superior and inferior vena cava.
3. The left atrium receives oxygenated blood from the pulmonary veins.
B. Atrial Systole
1. The atria contract and push blood into the ventricles.
2. The bicuspid (mitral) and tricuspid valves are open during this phase.
3. This ensures that the ventricles are completely filled with blood before contraction begins.
C. Ventricular Systole
1. The ventricles contract after the atria.
2. The AV valves (bicuspid and tricuspid) close to prevent backflow into the atria.
3. The closure of these valves produces the first heart sound “LUB.”
2. With every heartbeat, a series of events take place inside the heart — this is called the cardiac
cycle.
3. It includes the contraction (systole) and relaxation (diastole) of the atria and ventricles.
4. The cardiac cycle helps maintain a continuous flow of blood and keeps oxygen supply
constant.
Definition
2️2️⃣
1. The cardiac cycle is the complete sequence of events that occur in the heart during one
heartbeat.
2. It includes atrial contraction, ventricular contraction, and relaxation of both chambers.
3. One cardiac cycle lasts about 0.8 seconds in a healthy adult.
Duration
3️3️⃣
1. The heart beats about 72 times per minute.
2. Each cardiac cycle takes 0.8 seconds.
3. The duration of different phases is as follows:
Atrial systole: 0.1 second
Ventricular systole: 0.3 second
Complete diastole: 0.4 second
Phases of the Cardiac Cycle
4️4️⃣
A. Atrial Diastole
1. Both atria are relaxed and receive blood from the veins.
2. The right atrium receives deoxygenated blood from the superior and inferior vena cava.
3. The left atrium receives oxygenated blood from the pulmonary veins.
B. Atrial Systole
1. The atria contract and push blood into the ventricles.
2. The bicuspid (mitral) and tricuspid valves are open during this phase.
3. This ensures that the ventricles are completely filled with blood before contraction begins.
C. Ventricular Systole
1. The ventricles contract after the atria.
2. The AV valves (bicuspid and tricuspid) close to prevent backflow into the atria.
3. The closure of these valves produces the first heart sound “LUB.”
4. Pressure rises inside the ventricles.
5. The semilunar valves (aortic and pulmonary) open, and blood is ejected:
From the right ventricle → to the lungs through the pulmonary artery.
From the left ventricle → to the body through the aorta.
D. Ventricular Diastole
1. After blood is pumped out, the ventricles relax.
2. The pressure inside the ventricles falls below the pressure in the arteries.
3. The semilunar valves close to prevent blood from flowing backward.
4. This closing of semilunar valves produces the second heart sound “DUB.”
5. Both atria and ventricles now remain relaxed for a short time.
6. Blood again starts filling the atria, beginning the next cardiac cycle.
Heart Sounds
5️5️⃣
1. There are two normal heart sounds heard during one cardiac cycle.
First heart sound (LUB): due to closure of tricuspid and bicuspid valves.
Second heart sound (DUB): due to closure of semilunar valves.
Sequence of Events (Summary Order)
6️6️⃣
1. Atria fill with blood → atrial diastole.
2. Atria contract → blood moves into ventricles.
3. Ventricles contract → blood moves into lungs and body.
4. Semilunar valves close → ventricles relax.
5. Heart chambers refill with blood → new cycle begins.
Significance / Importance
7️7️⃣
1. It maintains continuous blood circulation in the body.
2. It ensures proper oxygen supply to all tissues.
3. It helps remove carbon dioxide and waste products.
4. It keeps blood pressure and rhythm of the heart normal.
5. Heart sounds help in identifying normal or abnormal heart function.
Duration Summary Table
8️8️⃣
PhaseTime (Seconds)
5. The semilunar valves (aortic and pulmonary) open, and blood is ejected:
From the right ventricle → to the lungs through the pulmonary artery.
From the left ventricle → to the body through the aorta.
D. Ventricular Diastole
1. After blood is pumped out, the ventricles relax.
2. The pressure inside the ventricles falls below the pressure in the arteries.
3. The semilunar valves close to prevent blood from flowing backward.
4. This closing of semilunar valves produces the second heart sound “DUB.”
5. Both atria and ventricles now remain relaxed for a short time.
6. Blood again starts filling the atria, beginning the next cardiac cycle.
Heart Sounds
5️5️⃣
1. There are two normal heart sounds heard during one cardiac cycle.
First heart sound (LUB): due to closure of tricuspid and bicuspid valves.
Second heart sound (DUB): due to closure of semilunar valves.
Sequence of Events (Summary Order)
6️6️⃣
1. Atria fill with blood → atrial diastole.
2. Atria contract → blood moves into ventricles.
3. Ventricles contract → blood moves into lungs and body.
4. Semilunar valves close → ventricles relax.
5. Heart chambers refill with blood → new cycle begins.
Significance / Importance
7️7️⃣
1. It maintains continuous blood circulation in the body.
2. It ensures proper oxygen supply to all tissues.
3. It helps remove carbon dioxide and waste products.
4. It keeps blood pressure and rhythm of the heart normal.
5. Heart sounds help in identifying normal or abnormal heart function.
Duration Summary Table
8️8️⃣
PhaseTime (Seconds)
Atrial Systole0.1 sec
Ventricular Systole0.3 sec
Complete Diastole0.4 sec
Total Cardiac Cycle0.8 sec
Flow Chart (Easy to Remember)
9️9️⃣
Atria fill with blood
↓
Atria contract → Blood flows into ventricles
↓
Ventricles contract → Blood flows to lungs and body
↓
Semilunar valves close → Heart relaxes
↓
Atria fill again → Next heartbeat begins
?????? Summary
1. The cardiac cycle is one complete heartbeat.
2. It consists of atrial contraction, ventricular contraction, and relaxation.
3. The total duration is 0.8 seconds.
4. It repeats about 72 times per minute throughout life to keep us alive.
Blood circulation
1. Introduction
Ventricular Systole0.3 sec
Complete Diastole0.4 sec
Total Cardiac Cycle0.8 sec
Flow Chart (Easy to Remember)
9️9️⃣
Atria fill with blood
↓
Atria contract → Blood flows into ventricles
↓
Ventricles contract → Blood flows to lungs and body
↓
Semilunar valves close → Heart relaxes
↓
Atria fill again → Next heartbeat begins
?????? Summary
1. The cardiac cycle is one complete heartbeat.
2. It consists of atrial contraction, ventricular contraction, and relaxation.
3. The total duration is 0.8 seconds.
4. It repeats about 72 times per minute throughout life to keep us alive.
Blood circulation
1. Introduction
The human body needs a constant supply of oxygen and nutrients to survive. This supply is made
possible by the process of blood circulation. Blood circulation refers to the continuous movement
of blood throughout the body, powered by the pumping action of the heart. This process not only
provides oxygen and nutrients but also removes carbon dioxide and waste products from the
body’s tissues. The circulatory system, therefore, acts as a transport and life-support system for
the body.
2. Definition
Blood circulation is the continuous movement of blood through the heart and blood vessels,
delivering oxygen and nutrients to tissues and carrying away waste products.
3. Components of the Circulatory System
1. Heart – muscular organ that pumps blood.
2. Blood – the fluid that carries oxygen, nutrients, hormones, and waste.
3. Blood vessels – pathways for blood flow:
Arteries: carry oxygenated blood from the heart to the body.
Veins: carry deoxygenated blood back to the heart.
Capillaries: tiny vessels where exchange of gases and nutrients takes place.
4. Types of Circulation
1. Pulmonary Circulation
Movement of blood between the heart and lungs.
Function: carries deoxygenated blood to the lungs and brings back oxygenated blood.
2. Systemic Circulation
Movement of blood between the heart and the rest of the body.
Function: delivers oxygenated blood to body tissues and brings back deoxygenated blood.
5. Pathway of Blood Circulation
1. Deoxygenated blood from the body → Right Atrium → Right Ventricle.
2. From Right Ventricle → Pulmonary Artery → Lungs (blood gets oxygenated).
3. Oxygenated blood → Pulmonary Veins → Left Atrium → Left Ventricle.
4. Left Ventricle → Aorta → Whole body (delivers oxygen).
5. Blood returns back to Right Atrium through veins → cycle repeats.
6. Importance of Blood Circulation
Supplies oxygen and nutrients to cells.
Removes carbon dioxide and waste products.
possible by the process of blood circulation. Blood circulation refers to the continuous movement
of blood throughout the body, powered by the pumping action of the heart. This process not only
provides oxygen and nutrients but also removes carbon dioxide and waste products from the
body’s tissues. The circulatory system, therefore, acts as a transport and life-support system for
the body.
2. Definition
Blood circulation is the continuous movement of blood through the heart and blood vessels,
delivering oxygen and nutrients to tissues and carrying away waste products.
3. Components of the Circulatory System
1. Heart – muscular organ that pumps blood.
2. Blood – the fluid that carries oxygen, nutrients, hormones, and waste.
3. Blood vessels – pathways for blood flow:
Arteries: carry oxygenated blood from the heart to the body.
Veins: carry deoxygenated blood back to the heart.
Capillaries: tiny vessels where exchange of gases and nutrients takes place.
4. Types of Circulation
1. Pulmonary Circulation
Movement of blood between the heart and lungs.
Function: carries deoxygenated blood to the lungs and brings back oxygenated blood.
2. Systemic Circulation
Movement of blood between the heart and the rest of the body.
Function: delivers oxygenated blood to body tissues and brings back deoxygenated blood.
5. Pathway of Blood Circulation
1. Deoxygenated blood from the body → Right Atrium → Right Ventricle.
2. From Right Ventricle → Pulmonary Artery → Lungs (blood gets oxygenated).
3. Oxygenated blood → Pulmonary Veins → Left Atrium → Left Ventricle.
4. Left Ventricle → Aorta → Whole body (delivers oxygen).
5. Blood returns back to Right Atrium through veins → cycle repeats.
6. Importance of Blood Circulation
Supplies oxygen and nutrients to cells.
Removes carbon dioxide and waste products.
Helps in maintaining body temperature.
Transports hormones and other essential substances.
Protects body through white blood cells and clotting.
7. Diagram
(Draw a neat labeled diagram of heart and circulation here – Pulmonary and Systemic.)
8. Conclusion
Blood circulation is essential for life. It ensures that every cell in the body receives the oxygen
and nutrients it needs while removing waste products. The heart, blood, and blood vessels
together form an efficient transport system that keeps the body alive and functioning. Without
circulation, survival is impossible, which is why the heart is often called the “engine of life.”
Steps of Blood Circulation in Humans
1. Deoxygenated blood from the body tissues collects into veins and finally enters the right
atrium of the heart through the superior and inferior vena cava.
2. From the right atrium, this blood passes through the tricuspid valve into the right ventricle.
3. The right ventricle contracts and pumps the deoxygenated blood through the pulmonary valve
into the pulmonary artery.
4. The pulmonary artery carries this blood to the lungs.
5. In the lungs, gas exchange takes place in the alveoli:
Carbon dioxide leaves the blood and enters the alveoli to be exhaled.
Oxygen from the inhaled air enters the blood.
6. The blood becomes oxygenated and returns to the heart through the pulmonary veins.
7. The pulmonary veins deliver the oxygenated blood into the left atrium.
8. From the left atrium, the blood flows through the mitral (bicuspid) valve into the left ventricle.
9. The left ventricle contracts powerfully and pumps the oxygenated blood through the aortic
valve into the aorta.
10. The aorta, the largest artery, distributes this oxygenated blood to the whole body through
arteries, arterioles, and capillaries.
11. In the body tissues, oxygen and nutrients are supplied to the cells, while carbon dioxide and
waste products are collected into the blood.
12. This blood becomes deoxygenated again and is carried back through veins into the superior
and inferior vena cava, which open into the right atrium.
MEIOSIS
??????
Definition
Transports hormones and other essential substances.
Protects body through white blood cells and clotting.
7. Diagram
(Draw a neat labeled diagram of heart and circulation here – Pulmonary and Systemic.)
8. Conclusion
Blood circulation is essential for life. It ensures that every cell in the body receives the oxygen
and nutrients it needs while removing waste products. The heart, blood, and blood vessels
together form an efficient transport system that keeps the body alive and functioning. Without
circulation, survival is impossible, which is why the heart is often called the “engine of life.”
Steps of Blood Circulation in Humans
1. Deoxygenated blood from the body tissues collects into veins and finally enters the right
atrium of the heart through the superior and inferior vena cava.
2. From the right atrium, this blood passes through the tricuspid valve into the right ventricle.
3. The right ventricle contracts and pumps the deoxygenated blood through the pulmonary valve
into the pulmonary artery.
4. The pulmonary artery carries this blood to the lungs.
5. In the lungs, gas exchange takes place in the alveoli:
Carbon dioxide leaves the blood and enters the alveoli to be exhaled.
Oxygen from the inhaled air enters the blood.
6. The blood becomes oxygenated and returns to the heart through the pulmonary veins.
7. The pulmonary veins deliver the oxygenated blood into the left atrium.
8. From the left atrium, the blood flows through the mitral (bicuspid) valve into the left ventricle.
9. The left ventricle contracts powerfully and pumps the oxygenated blood through the aortic
valve into the aorta.
10. The aorta, the largest artery, distributes this oxygenated blood to the whole body through
arteries, arterioles, and capillaries.
11. In the body tissues, oxygen and nutrients are supplied to the cells, while carbon dioxide and
waste products are collected into the blood.
12. This blood becomes deoxygenated again and is carried back through veins into the superior
and inferior vena cava, which open into the right atrium.
MEIOSIS
??????
Definition
Meiosis is a special type of cell division in which a diploid (2n) parent cell divides twice to form
four haploid (n) daughter cells, each genetically different from the parent cell.
It occurs in reproductive or germ cells for the formation of gametes (sperm and ovum).
??????
Purpose of Meiosis
1. To produce gametes for sexual reproduction.
2. To reduce the chromosome number by half, maintaining stability of species.
3. To create genetic variation through the process of crossing over.
4. To help in heredity and evolution.
??????
Types of Meiosis
Meiosis takes place in two continuous stages:
1. Meiosis I – Reductional Division
2. Meiosis II – Equational Division
??????
MEIOSIS I – Reductional Division
In this stage, the chromosome number is reduced to half (2n → n) because homologous
chromosomes separate.
1. Interphase
It is the resting or preparatory phase before division.
DNA replication takes place.
Chromosomes appear as fine thread-like chromatin.
Cell prepares itself for division.
2. Prophase I
Chromosomes condense and become visible.
Homologous chromosomes pair up (this is called synapsis).
Crossing over occurs — exchange of genetic material between homologous chromosomes.
Nuclear membrane and nucleolus disappear.
Spindle fibers begin to form from centrosomes.
3. Metaphase I
The paired homologous chromosomes align along the equatorial plate.
Spindle fibers attach to the centromere of each homologous pair.
4. Anaphase I
Homologous chromosomes move to opposite poles.
four haploid (n) daughter cells, each genetically different from the parent cell.
It occurs in reproductive or germ cells for the formation of gametes (sperm and ovum).
??????
Purpose of Meiosis
1. To produce gametes for sexual reproduction.
2. To reduce the chromosome number by half, maintaining stability of species.
3. To create genetic variation through the process of crossing over.
4. To help in heredity and evolution.
??????
Types of Meiosis
Meiosis takes place in two continuous stages:
1. Meiosis I – Reductional Division
2. Meiosis II – Equational Division
??????
MEIOSIS I – Reductional Division
In this stage, the chromosome number is reduced to half (2n → n) because homologous
chromosomes separate.
1. Interphase
It is the resting or preparatory phase before division.
DNA replication takes place.
Chromosomes appear as fine thread-like chromatin.
Cell prepares itself for division.
2. Prophase I
Chromosomes condense and become visible.
Homologous chromosomes pair up (this is called synapsis).
Crossing over occurs — exchange of genetic material between homologous chromosomes.
Nuclear membrane and nucleolus disappear.
Spindle fibers begin to form from centrosomes.
3. Metaphase I
The paired homologous chromosomes align along the equatorial plate.
Spindle fibers attach to the centromere of each homologous pair.
4. Anaphase I
Homologous chromosomes move to opposite poles.
Each pole receives half the number of chromosomes.
The chromosome number is reduced to half.
5. Telophase I and Cytokinesis I
Nuclear membrane reforms around the chromosomes.
Cytoplasm divides forming two haploid daughter cells.
Each new cell now contains half the number of chromosomes as the parent cell.
??????
MEIOSIS II – Equational Division
This stage resembles mitosis.
The two haploid cells formed in Meiosis I divide again without further DNA replication.
Chromosome number remains the same (n → n), but sister chromatids separate.
1. Prophase II
Chromosomes become short and thick again.
Spindle fibers form from opposite poles.
Nuclear membrane and nucleolus disappear.
2. Metaphase II
Chromosomes line up at the center (equatorial plate).
Spindle fibers attach to the centromere of each chromosome.
3. Anaphase II
Sister chromatids separate and move to opposite poles.
Each chromatid now acts as an individual chromosome.
4. Telophase II and Cytokinesis II
Chromosomes reach the poles and uncoil into chromatin.
Nuclear membrane and nucleolus reappear.
Cytoplasm divides to form four haploid daughter cells.
Each new cell has half the chromosome number and is genetically unique.
??????
Final Result
At the end of meiosis, one diploid parent cell produces four haploid daughter cells.
These cells are genetically different from each other due to crossing over in Prophase I.
They function as gametes in sexual reproduction.
??????
Significance of Meiosis
The chromosome number is reduced to half.
5. Telophase I and Cytokinesis I
Nuclear membrane reforms around the chromosomes.
Cytoplasm divides forming two haploid daughter cells.
Each new cell now contains half the number of chromosomes as the parent cell.
??????
MEIOSIS II – Equational Division
This stage resembles mitosis.
The two haploid cells formed in Meiosis I divide again without further DNA replication.
Chromosome number remains the same (n → n), but sister chromatids separate.
1. Prophase II
Chromosomes become short and thick again.
Spindle fibers form from opposite poles.
Nuclear membrane and nucleolus disappear.
2. Metaphase II
Chromosomes line up at the center (equatorial plate).
Spindle fibers attach to the centromere of each chromosome.
3. Anaphase II
Sister chromatids separate and move to opposite poles.
Each chromatid now acts as an individual chromosome.
4. Telophase II and Cytokinesis II
Chromosomes reach the poles and uncoil into chromatin.
Nuclear membrane and nucleolus reappear.
Cytoplasm divides to form four haploid daughter cells.
Each new cell has half the chromosome number and is genetically unique.
??????
Final Result
At the end of meiosis, one diploid parent cell produces four haploid daughter cells.
These cells are genetically different from each other due to crossing over in Prophase I.
They function as gametes in sexual reproduction.
??????
Significance of Meiosis
Maintains a constant chromosome number from generation to generation.
Produces haploid gametes essential for fertilization.
Introduces genetic variation which is important for evolution.
Ensures proper distribution of chromosomes to daughter cells.
FLOWCHART OF MEIOSIS
Parent Diploid Cell (2n)
⬇️
DNA Replication (Interphase)
⬇️
MEIOSIS–I (Reduction Division)
➡ Prophase I – Crossing over occurs
➡ Metaphase I – Homologous pairs align at equator
➡ Anaphase I – Homologous chromosomes move to opposite poles
➡ Telophase I – Two haploid cells form
⬇️
MEIOSIS–II (Equational Division)
➡ Prophase II – New spindle fibers form
➡ Metaphase II – Chromosomes line at equator
➡ Anaphase II – Sister chromatids separate
➡ Telophase II – Four haploid daughter cells form
⬇️
Final Result → 4 Haploid (n) Cells – Genetically Different
Physiology of Neuron
Definition
1️1️⃣
A neuron is the structural and functional unit of the nervous system.
Produces haploid gametes essential for fertilization.
Introduces genetic variation which is important for evolution.
Ensures proper distribution of chromosomes to daughter cells.
FLOWCHART OF MEIOSIS
Parent Diploid Cell (2n)
⬇️
DNA Replication (Interphase)
⬇️
MEIOSIS–I (Reduction Division)
➡ Prophase I – Crossing over occurs
➡ Metaphase I – Homologous pairs align at equator
➡ Anaphase I – Homologous chromosomes move to opposite poles
➡ Telophase I – Two haploid cells form
⬇️
MEIOSIS–II (Equational Division)
➡ Prophase II – New spindle fibers form
➡ Metaphase II – Chromosomes line at equator
➡ Anaphase II – Sister chromatids separate
➡ Telophase II – Four haploid daughter cells form
⬇️
Final Result → 4 Haploid (n) Cells – Genetically Different
Physiology of Neuron
Definition
1️1️⃣
A neuron is the structural and functional unit of the nervous system.
It receives, carries, and transmits nerve impulses.
The human brain contains about 86 billion neurons.
Parts of a Neuron
2️2️⃣
1. Cell Body (Soma) – contains the nucleus; controls metabolism and processing.
2. Dendrites – short branches that receive signals from other neurons.
3. Axon – long fiber carrying impulses away from the cell body.
4. Myelin Sheath – fatty covering that insulates the axon and increases speed.
5. Nodes of Ranvier – small gaps in the myelin sheath where impulses jump quickly.
6. Axon Terminals – end parts that transmit signals to the next neuron, muscle, or gland.
Stages of Nerve Impulse Transmission
3️3️⃣
Step 1 – Resting Membrane Potential
The neuron is at rest (–70 mV).
Inside is negative, outside is positive.
More K⁺ ions move out than Na⁺ move in.
The neuron is said to be polarized.
Step 2 – Depolarization
When a stimulus is received, Na⁺ channels open.
Na⁺ ions rush inside, making the inside positive.
This change is called depolarization.
Step 3 – Repolarization
K⁺ channels open; K⁺ ions move out of the cell.
Inside becomes negative again.
This returns the membrane toward resting state.
Step 4 – Hyperpolarization
The membrane becomes slightly more negative than normal for a short time.
Step 5 – Restoration
The sodium–potassium pump restores the normal ion balance.
The neuron becomes ready for the next impulse.
Direction of Nerve Impulse
4️4️⃣
➡️
Dendrite → Cell Body → Axon → Axon Terminal → Next Neuron
The human brain contains about 86 billion neurons.
Parts of a Neuron
2️2️⃣
1. Cell Body (Soma) – contains the nucleus; controls metabolism and processing.
2. Dendrites – short branches that receive signals from other neurons.
3. Axon – long fiber carrying impulses away from the cell body.
4. Myelin Sheath – fatty covering that insulates the axon and increases speed.
5. Nodes of Ranvier – small gaps in the myelin sheath where impulses jump quickly.
6. Axon Terminals – end parts that transmit signals to the next neuron, muscle, or gland.
Stages of Nerve Impulse Transmission
3️3️⃣
Step 1 – Resting Membrane Potential
The neuron is at rest (–70 mV).
Inside is negative, outside is positive.
More K⁺ ions move out than Na⁺ move in.
The neuron is said to be polarized.
Step 2 – Depolarization
When a stimulus is received, Na⁺ channels open.
Na⁺ ions rush inside, making the inside positive.
This change is called depolarization.
Step 3 – Repolarization
K⁺ channels open; K⁺ ions move out of the cell.
Inside becomes negative again.
This returns the membrane toward resting state.
Step 4 – Hyperpolarization
The membrane becomes slightly more negative than normal for a short time.
Step 5 – Restoration
The sodium–potassium pump restores the normal ion balance.
The neuron becomes ready for the next impulse.
Direction of Nerve Impulse
4️4️⃣
➡️
Dendrite → Cell Body → Axon → Axon Terminal → Next Neuron
Synapse and Transmission
5️5️⃣
The point where two neurons meet is called a synapse.
The presynaptic neuron sends the impulse; the postsynaptic neuron receives it.
Transmission occurs through a chemical messenger called neurotransmitter (e.g., acetylcholine).
The neurotransmitter crosses the synaptic cleft and starts a new impulse in the next neuron.
Types of Neurons
6️6️⃣
A. Based on Structure
1. Unipolar – one process; seen in embryonic stage.
2. Bipolar – one axon + one dendrite (e.g., retina of eye).
3. Multipolar – one axon + many dendrites (e.g., brain, spinal cord).
4. Pseudounipolar – one axon divided into two branches (e.g., spinal ganglion).
B. Based on Function
1. Sensory Neuron – carries messages from sense organs to CNS.
2. Interneuron (Relay Neuron) – connects sensory and motor neurons.
3. Motor Neuron – carries messages from CNS to muscles or glands.
Functions of Neuron
7️7️⃣
1. Sensory Function – receives information from sense organs.
2. Integrative Function – interprets and processes the information.
3. Motor Function – sends command to muscles or glands for action.
4. Coordination – maintains communication between all body parts.
Important Points
8️8️⃣
Nerve impulse is an electrical and chemical signal.
It always travels in one direction only.
Myelinated neurons conduct impulses faster than unmyelinated ones.
Normal conduction speed = about 120 m/sec in myelinated fibers.
Flow Chart – Transmission of Nerve Impulse in a Neuron
Neuron at Rest
↓
Resting Membrane Potential (–70 mV)
→ Inside negative, outside positive
↓
5️5️⃣
The point where two neurons meet is called a synapse.
The presynaptic neuron sends the impulse; the postsynaptic neuron receives it.
Transmission occurs through a chemical messenger called neurotransmitter (e.g., acetylcholine).
The neurotransmitter crosses the synaptic cleft and starts a new impulse in the next neuron.
Types of Neurons
6️6️⃣
A. Based on Structure
1. Unipolar – one process; seen in embryonic stage.
2. Bipolar – one axon + one dendrite (e.g., retina of eye).
3. Multipolar – one axon + many dendrites (e.g., brain, spinal cord).
4. Pseudounipolar – one axon divided into two branches (e.g., spinal ganglion).
B. Based on Function
1. Sensory Neuron – carries messages from sense organs to CNS.
2. Interneuron (Relay Neuron) – connects sensory and motor neurons.
3. Motor Neuron – carries messages from CNS to muscles or glands.
Functions of Neuron
7️7️⃣
1. Sensory Function – receives information from sense organs.
2. Integrative Function – interprets and processes the information.
3. Motor Function – sends command to muscles or glands for action.
4. Coordination – maintains communication between all body parts.
Important Points
8️8️⃣
Nerve impulse is an electrical and chemical signal.
It always travels in one direction only.
Myelinated neurons conduct impulses faster than unmyelinated ones.
Normal conduction speed = about 120 m/sec in myelinated fibers.
Flow Chart – Transmission of Nerve Impulse in a Neuron
Neuron at Rest
↓
Resting Membrane Potential (–70 mV)
→ Inside negative, outside positive
↓
Stimulus Received
↓
Depolarization
→ Sodium (Na⁺) channels open
→ Na⁺ ions rush into neuron
→ Inside becomes positive
↓
Repolarization
→ Potassium (K⁺) channels open
→ K⁺ ions move out (exit)
→ Inside becomes negative again
↓
Hyperpolarization
→ Membrane becomes slightly more negative for a short time
↓
Restoration of Resting State
→ Sodium–Potassium pump restores normal ion balance
↓
Impulse Travels Along Axon
↓
Reaches Axon Terminal
↓
Synapse
→ Neurotransmitter (e.g., Acetylcholine) released
→ Crosses synaptic cleft
→ Stimulates next neuron
↓
Direction of Impulse:
Dendrite → Cell Body → Axon → Axon Terminal → Next Neuron
Title to write below in record:
??????
Flow Chart Showing the Physiology and Transmission of
Nerve Impulse in a Neuron
MITOSIS
??????
Definition
Mitosis is a process where one parent (diploid) cell divides to form two identical daughter cells,
each having the same number and type of chromosomes (diploid → diploid) as the parent cell.
??????
Phases of Mitosis
Mitosis occurs in six stages:
↓
Depolarization
→ Sodium (Na⁺) channels open
→ Na⁺ ions rush into neuron
→ Inside becomes positive
↓
Repolarization
→ Potassium (K⁺) channels open
→ K⁺ ions move out (exit)
→ Inside becomes negative again
↓
Hyperpolarization
→ Membrane becomes slightly more negative for a short time
↓
Restoration of Resting State
→ Sodium–Potassium pump restores normal ion balance
↓
Impulse Travels Along Axon
↓
Reaches Axon Terminal
↓
Synapse
→ Neurotransmitter (e.g., Acetylcholine) released
→ Crosses synaptic cleft
→ Stimulates next neuron
↓
Direction of Impulse:
Dendrite → Cell Body → Axon → Axon Terminal → Next Neuron
Title to write below in record:
??????
Flow Chart Showing the Physiology and Transmission of
Nerve Impulse in a Neuron
MITOSIS
??????
Definition
Mitosis is a process where one parent (diploid) cell divides to form two identical daughter cells,
each having the same number and type of chromosomes (diploid → diploid) as the parent cell.
??????
Phases of Mitosis
Mitosis occurs in six stages:
Interphase
1 ️1️⃣
Prophase
2 ️2️⃣
Metaphase
3 ️3️⃣
Anaphase
4 ️4️⃣
Telophase
5 ️5️⃣
Cytokinesis
6 ️6️⃣
??????
1. Interphase
(Resting but metabolically active phase)
1. The cell grows in size and prepares for division.
2. DNA replication occurs (S phase).
3. Centrosome duplicates.
4. Nucleus and nucleolus are clearly visible.
??????
Tip
: Interphase is a preparatory or resting phase, but active in protein and DNA synthesis.
??????
2. Prophase
1. Chromatin condenses into visible chromosomes.
2. Each chromosome shows two sister chromatids joined at the centromere.
3. Nuclear membrane and nucleolus disappear.
4. Spindle fibers form from centrioles at opposite poles.
??????
3. Metaphase
1. Chromosomes align at the equatorial plate (center) of the cell.
2. Spindle fibers attach to the centromere of each chromosome.
3. This is the best stage for studying chromosomes under a microscope.
??????
4. Anaphase
1. Centromeres divide and the sister chromatids separate.
2. Spindle fibers shorten, pulling chromatids to opposite poles.
3. It is the shortest stage of mitosis.
??????
5. Telophase
1. Chromatids reach the poles and uncoil into chromatin threads.
2. Nuclear membrane and nucleolus reappear.
3. Two new nuclei are formed in a single cell.
??????
6. Cytokinesis
1. Cytoplasm divides into two equal parts.
2. Two identical daughter cells are formed.
3. In animal cells: cleavage furrow forms.
In plant cells: cell plate forms.
4. Each daughter cell has the same chromosome number (2n) as the parent cell.
??????
Significance of Mitosis
1 ️1️⃣
Prophase
2 ️2️⃣
Metaphase
3 ️3️⃣
Anaphase
4 ️4️⃣
Telophase
5 ️5️⃣
Cytokinesis
6 ️6️⃣
??????
1. Interphase
(Resting but metabolically active phase)
1. The cell grows in size and prepares for division.
2. DNA replication occurs (S phase).
3. Centrosome duplicates.
4. Nucleus and nucleolus are clearly visible.
??????
Tip
: Interphase is a preparatory or resting phase, but active in protein and DNA synthesis.
??????
2. Prophase
1. Chromatin condenses into visible chromosomes.
2. Each chromosome shows two sister chromatids joined at the centromere.
3. Nuclear membrane and nucleolus disappear.
4. Spindle fibers form from centrioles at opposite poles.
??????
3. Metaphase
1. Chromosomes align at the equatorial plate (center) of the cell.
2. Spindle fibers attach to the centromere of each chromosome.
3. This is the best stage for studying chromosomes under a microscope.
??????
4. Anaphase
1. Centromeres divide and the sister chromatids separate.
2. Spindle fibers shorten, pulling chromatids to opposite poles.
3. It is the shortest stage of mitosis.
??????
5. Telophase
1. Chromatids reach the poles and uncoil into chromatin threads.
2. Nuclear membrane and nucleolus reappear.
3. Two new nuclei are formed in a single cell.
??????
6. Cytokinesis
1. Cytoplasm divides into two equal parts.
2. Two identical daughter cells are formed.
3. In animal cells: cleavage furrow forms.
In plant cells: cell plate forms.
4. Each daughter cell has the same chromosome number (2n) as the parent cell.
??????
Significance of Mitosis
1. Helps in growth and development of multicellular organisms.
2. Responsible for repair and replacement of damaged or old cells.
3. Maintains same chromosome number in all somatic cells.
4. Helps in healing of wounds.
5. Ensures genetic stability — daughter cells are exact copies of the parent cell.
6. Plays an important role in asexual reproduction of unicellular organisms.
??????
Flow Chart – Stages of Mitosis
INTERPHASE
↓ (Preparation for division)
PROPHASE
↓ (Chromosomes form, spindle appears)
METAPHASE
↓ (Chromosomes align at equator)
ANAPHASE
↓ (Chromatids move to opposite poles)
TELOPHASE
↓ (Two nuclei reappear)
CYTOKINESIS
↓
TWO IDENTICAL DAUGHTER CELLS
Mnemonic for Easy Memory
“Foolish People Try Climbing Long Slopes After Christmas, Some People Have Fallen.”
(F = I, P = II, T = III, C = IV, L = V, S = VII, A = VIII, C = IX, S = X, P = XI, H = XII, F = XIII)
??????
Easy Mnemonic to Remember All Factors
“Foolish People Try Climbing Long Slopes After Christmas, Some People Have Fallen.”
F – Fibrinogen
P – Prothrombin T – Thromboplastin C – Calcium L – Labile S –
Stable
A – Anti-hemophilic C – Christmas S – Stuart-Prower P – Plasma Thromboplastin
Antecedent
H – Hageman F – Fibrin-stabilizing.
Question 1 – Blood Clotting Factors (I–XIII)
??????
Introduction
When a blood vessel is injured, bleeding starts immediately.
After a short time, the bleeding stops automatically due to a natural protective process called
blood clotting or coagulation.
This mechanism prevents excessive blood loss and helps in wound healing.
??????
Definition
Blood clotting factors are special plasma proteins and ions that help in the conversion of liquid
blood into a semisolid clot.
2. Responsible for repair and replacement of damaged or old cells.
3. Maintains same chromosome number in all somatic cells.
4. Helps in healing of wounds.
5. Ensures genetic stability — daughter cells are exact copies of the parent cell.
6. Plays an important role in asexual reproduction of unicellular organisms.
??????
Flow Chart – Stages of Mitosis
INTERPHASE
↓ (Preparation for division)
PROPHASE
↓ (Chromosomes form, spindle appears)
METAPHASE
↓ (Chromosomes align at equator)
ANAPHASE
↓ (Chromatids move to opposite poles)
TELOPHASE
↓ (Two nuclei reappear)
CYTOKINESIS
↓
TWO IDENTICAL DAUGHTER CELLS
Mnemonic for Easy Memory
“Foolish People Try Climbing Long Slopes After Christmas, Some People Have Fallen.”
(F = I, P = II, T = III, C = IV, L = V, S = VII, A = VIII, C = IX, S = X, P = XI, H = XII, F = XIII)
??????
Easy Mnemonic to Remember All Factors
“Foolish People Try Climbing Long Slopes After Christmas, Some People Have Fallen.”
F – Fibrinogen
P – Prothrombin T – Thromboplastin C – Calcium L – Labile S –
Stable
A – Anti-hemophilic C – Christmas S – Stuart-Prower P – Plasma Thromboplastin
Antecedent
H – Hageman F – Fibrin-stabilizing.
Question 1 – Blood Clotting Factors (I–XIII)
??????
Introduction
When a blood vessel is injured, bleeding starts immediately.
After a short time, the bleeding stops automatically due to a natural protective process called
blood clotting or coagulation.
This mechanism prevents excessive blood loss and helps in wound healing.
??????
Definition
Blood clotting factors are special plasma proteins and ions that help in the conversion of liquid
blood into a semisolid clot.
They are numbered from I to XIII, produced mainly by the liver, and work together in a definite
sequence to stop bleeding.
??????
List and Functions of Blood Clotting Factors
1. Factor I – Fibrinogen
It is a plasma protein produced by the liver.
It is converted into fibrin threads by thrombin, forming the main structure of the clot.
2. Factor II – Prothrombin
It is a vitamin K-dependent protein made by the liver.
It changes into thrombin, which is the main enzyme responsible for clot formation.
3. Factor III – Thromboplastin (Tissue Factor)
It is released from damaged tissues.
It initiates the extrinsic pathway of coagulation and helps activate Factor VII.
4. Factor IV – Calcium Ions (Ca² ⁺ )
Calcium is essential in almost every stage of the clotting process.
It acts as a co-factor for activation of many clotting factors.
5. Factor V – Proaccelerin (Labile Factor)
It works together with Factor X to form prothrombin activator, which converts prothrombin to
thrombin.
6. Factor VI – Not in use
This factor was previously called Accelerin but is no longer considered separate.
7. Factor VII – Proconvertin (Stable Factor)
It is a vitamin K-dependent factor produced by the liver.
It helps activate Factor X in the extrinsic pathway.
8. Factor VIII – Anti-hemophilic Factor A
It participates in the intrinsic pathway along with Factor IX to activate Factor X.
Deficiency of this factor causes Hemophilia A.
9. Factor IX – Christmas Factor (Anti-hemophilic Factor B)
It works with Factor VIII to activate Factor X.
Deficiency of this factor causes Hemophilia B.
10. Factor X – Stuart–Prower Factor
It is the common meeting point for both intrinsic and extrinsic pathways.
It helps form prothrombin activator which converts prothrombin to thrombin.
11. Factor XI – Plasma Thromboplastin Antecedent
It activates Factor IX in the intrinsic pathway.
Its deficiency causes Hemophilia C.
12. Factor XII – Hageman Factor (Contact Activation Factor)
It initiates the intrinsic pathway when blood contacts a rough or damaged surface.
sequence to stop bleeding.
??????
List and Functions of Blood Clotting Factors
1. Factor I – Fibrinogen
It is a plasma protein produced by the liver.
It is converted into fibrin threads by thrombin, forming the main structure of the clot.
2. Factor II – Prothrombin
It is a vitamin K-dependent protein made by the liver.
It changes into thrombin, which is the main enzyme responsible for clot formation.
3. Factor III – Thromboplastin (Tissue Factor)
It is released from damaged tissues.
It initiates the extrinsic pathway of coagulation and helps activate Factor VII.
4. Factor IV – Calcium Ions (Ca² ⁺ )
Calcium is essential in almost every stage of the clotting process.
It acts as a co-factor for activation of many clotting factors.
5. Factor V – Proaccelerin (Labile Factor)
It works together with Factor X to form prothrombin activator, which converts prothrombin to
thrombin.
6. Factor VI – Not in use
This factor was previously called Accelerin but is no longer considered separate.
7. Factor VII – Proconvertin (Stable Factor)
It is a vitamin K-dependent factor produced by the liver.
It helps activate Factor X in the extrinsic pathway.
8. Factor VIII – Anti-hemophilic Factor A
It participates in the intrinsic pathway along with Factor IX to activate Factor X.
Deficiency of this factor causes Hemophilia A.
9. Factor IX – Christmas Factor (Anti-hemophilic Factor B)
It works with Factor VIII to activate Factor X.
Deficiency of this factor causes Hemophilia B.
10. Factor X – Stuart–Prower Factor
It is the common meeting point for both intrinsic and extrinsic pathways.
It helps form prothrombin activator which converts prothrombin to thrombin.
11. Factor XI – Plasma Thromboplastin Antecedent
It activates Factor IX in the intrinsic pathway.
Its deficiency causes Hemophilia C.
12. Factor XII – Hageman Factor (Contact Activation Factor)
It initiates the intrinsic pathway when blood contacts a rough or damaged surface.
13. Factor XIII – Fibrin-stabilizing Factor
It strengthens and stabilizes the fibrin mesh to form a firm, stable clot.
??????
Vitamin K-Dependent Factors
Factors II, VII, IX, and X require vitamin K for their synthesis in the liver.
??????
Deficiency Disorders
Hemophilia A – deficiency of Factor VIII
Hemophilia B – deficiency of Factor IX
Hemophilia C – deficiency of Factor XI
Vitamin K deficiency – affects Factors II, VII, IX, X and delays clotting
??????
Importance
1. Clotting factors prevent excessive bleeding after injury.
2. They help maintain blood volume and pressure.
3. They protect the body from infection by sealing wounds.
4. They assist in the repair and healing of tissues.
??????
Conclusion
Blood clotting factors are essential plasma components that act in a fixed sequence to form a
blood clot.
They are vital for normal hemostasis, and any deficiency can lead to bleeding disorders such as
hemophilia.
Blood Coagulation (Mechanism of Blood Clotting)
Flow Chart: Sequential Steps of Blood Coagulation
??????
Injury to Blood Vessel
⬇️
Damage to Vessel Wall
⬇️
Platelets Activated and Stick to Injured Area
⬇️
Platelets Release Thromboplastin (Tissue Factor) and Serotonin
It strengthens and stabilizes the fibrin mesh to form a firm, stable clot.
??????
Vitamin K-Dependent Factors
Factors II, VII, IX, and X require vitamin K for their synthesis in the liver.
??????
Deficiency Disorders
Hemophilia A – deficiency of Factor VIII
Hemophilia B – deficiency of Factor IX
Hemophilia C – deficiency of Factor XI
Vitamin K deficiency – affects Factors II, VII, IX, X and delays clotting
??????
Importance
1. Clotting factors prevent excessive bleeding after injury.
2. They help maintain blood volume and pressure.
3. They protect the body from infection by sealing wounds.
4. They assist in the repair and healing of tissues.
??????
Conclusion
Blood clotting factors are essential plasma components that act in a fixed sequence to form a
blood clot.
They are vital for normal hemostasis, and any deficiency can lead to bleeding disorders such as
hemophilia.
Blood Coagulation (Mechanism of Blood Clotting)
Flow Chart: Sequential Steps of Blood Coagulation
??????
Injury to Blood Vessel
⬇️
Damage to Vessel Wall
⬇️
Platelets Activated and Stick to Injured Area
⬇️
Platelets Release Thromboplastin (Tissue Factor) and Serotonin
⬇️
Thromboplastin + Factor X + Factor V + Calcium (Factor IV) + Phospholipids
⬇️
➡️
Formation of Prothrombin Activator
⬇️
Prothrombin (Factor II)
⬇️
(in presence of Calcium ions)
➡️
Converted into Thrombin
⬇️
Fibrinogen (Factor I)
⬇️
(by action of Thrombin)
➡️
Converted into Fibrin Threads
⬇️
Fibrin Threads Form Meshwork → Trap RBCs and Platelets
⬇️
Factor XIII Strengthens and Stabilizes the Fibrin Mesh
⬇️
Formation of Stable Fibrin Clot
⬇️
Bleeding Stops → Healing Begins
Physiology of Formation of Urine (Point-wise)
Introduction
1️1️⃣
1. Urine is formed in the nephrons of the kidney.
2. Each kidney has about one million nephrons.
3. The nephron filters blood and maintains water, electrolyte, and acid–base balance.
4. Urine formation occurs through five steps:
Glomerular Filtration
Tubular Reabsorption
Tubular Secretion
Thromboplastin + Factor X + Factor V + Calcium (Factor IV) + Phospholipids
⬇️
➡️
Formation of Prothrombin Activator
⬇️
Prothrombin (Factor II)
⬇️
(in presence of Calcium ions)
➡️
Converted into Thrombin
⬇️
Fibrinogen (Factor I)
⬇️
(by action of Thrombin)
➡️
Converted into Fibrin Threads
⬇️
Fibrin Threads Form Meshwork → Trap RBCs and Platelets
⬇️
Factor XIII Strengthens and Stabilizes the Fibrin Mesh
⬇️
Formation of Stable Fibrin Clot
⬇️
Bleeding Stops → Healing Begins
Physiology of Formation of Urine (Point-wise)
Introduction
1️1️⃣
1. Urine is formed in the nephrons of the kidney.
2. Each kidney has about one million nephrons.
3. The nephron filters blood and maintains water, electrolyte, and acid–base balance.
4. Urine formation occurs through five steps:
Glomerular Filtration
Tubular Reabsorption
Tubular Secretion
Concentration and Dilution
Excretion
Glomerular Filtration
2️2️⃣
1. Blood enters the glomerulus through the afferent arteriole.
2. Blood pressure (glomerular hydrostatic pressure) forces water and small molecules through the
glomerular membrane into Bowman’s capsule.
3. The fluid that enters Bowman’s capsule is called glomerular filtrate.
4. Proteins and blood cells are too large to pass through the filter.
5. Filtration depends on three pressures:
Glomerular hydrostatic pressure (favors filtration)
Capsular pressure (opposes filtration)
Colloidal osmotic pressure (opposes filtration)
6. Net filtration pressure ≈ 10 mm Hg.
7. About 180 L of filtrate is formed daily in both kidneys.
Tubular Reabsorption
3️3️⃣
1. The filtrate passes through PCT → Loop of Henle → DCT → Collecting duct.
2. Useful substances like glucose, amino acids, sodium, chloride, and water are reabsorbed into
the blood.
3. PCT reabsorbs about 65–70 % of the filtrate.
4. Loop of Henle:
Descending limb → reabsorbs water.
Ascending limb → reabsorbs sodium and chloride.
5. DCT and collecting duct perform further reabsorption under hormonal control.
6. Reabsorbed substances enter the blood through peritubular capillaries.
7. Reabsorption keeps the body’s water and nutrient balance normal.
Tubular Secretion
4️4️⃣
1. Certain wastes are added from blood into the tubule — H⁺, K⁺, NH₃, and drugs.
2. This process helps remove toxic materials from the body.
3. Secretion mainly occurs in the DCT and collecting duct.
4. It helps maintain acid–base balance (pH) of blood.
Concentration and Dilution of Urine
5️5️⃣
1. The loop of Henle and vasa recta work as a counter-current mechanism to concentrate urine.
2. Aldosterone increases sodium reabsorption and potassium excretion.
3. ADH (Antidiuretic Hormone) increases water reabsorption in DCT and collecting duct.
4. When ADH level is high → concentrated urine (less water).
5. When ADH level is low → dilute urine (more water).
Excretion
Glomerular Filtration
2️2️⃣
1. Blood enters the glomerulus through the afferent arteriole.
2. Blood pressure (glomerular hydrostatic pressure) forces water and small molecules through the
glomerular membrane into Bowman’s capsule.
3. The fluid that enters Bowman’s capsule is called glomerular filtrate.
4. Proteins and blood cells are too large to pass through the filter.
5. Filtration depends on three pressures:
Glomerular hydrostatic pressure (favors filtration)
Capsular pressure (opposes filtration)
Colloidal osmotic pressure (opposes filtration)
6. Net filtration pressure ≈ 10 mm Hg.
7. About 180 L of filtrate is formed daily in both kidneys.
Tubular Reabsorption
3️3️⃣
1. The filtrate passes through PCT → Loop of Henle → DCT → Collecting duct.
2. Useful substances like glucose, amino acids, sodium, chloride, and water are reabsorbed into
the blood.
3. PCT reabsorbs about 65–70 % of the filtrate.
4. Loop of Henle:
Descending limb → reabsorbs water.
Ascending limb → reabsorbs sodium and chloride.
5. DCT and collecting duct perform further reabsorption under hormonal control.
6. Reabsorbed substances enter the blood through peritubular capillaries.
7. Reabsorption keeps the body’s water and nutrient balance normal.
Tubular Secretion
4️4️⃣
1. Certain wastes are added from blood into the tubule — H⁺, K⁺, NH₃, and drugs.
2. This process helps remove toxic materials from the body.
3. Secretion mainly occurs in the DCT and collecting duct.
4. It helps maintain acid–base balance (pH) of blood.
Concentration and Dilution of Urine
5️5️⃣
1. The loop of Henle and vasa recta work as a counter-current mechanism to concentrate urine.
2. Aldosterone increases sodium reabsorption and potassium excretion.
3. ADH (Antidiuretic Hormone) increases water reabsorption in DCT and collecting duct.
4. When ADH level is high → concentrated urine (less water).
5. When ADH level is low → dilute urine (more water).
6. This process maintains body water, electrolyte balance, and blood pressure.
Excretion of Urine
6️6️⃣
1. After all these steps, the remaining fluid is urine.
2. Urine contains urea, uric acid, creatinine, salts, and water.
3. Urine passes through collecting ducts → renal pelvis → ureter → urinary bladder → urethra
→ outside body.
4. Out of 180 L of filtrate, about 99 % is reabsorbed and only 1–1.5 L/day is excreted as urine.
5. Normal urine:
Pale yellow in color
Slightly acidic (pH ≈ 6)
Free from protein, sugar, and blood cells
Easy Formula to Remember
7️7️⃣
F – R – S – C – E
??????
→ Filtration – Reabsorption – Secretion – Concentration – EXCRETION
Blood in Renal Artery
↓
Reaches Glomerulus (in Bowman’s Capsule)
↓
Glomerular Filtration
→ Water, glucose, salts, urea filter out
→ Large proteins & blood cells remain
↓
Glomerular Filtrate (Primary Urine)
Excretion of Urine
6️6️⃣
1. After all these steps, the remaining fluid is urine.
2. Urine contains urea, uric acid, creatinine, salts, and water.
3. Urine passes through collecting ducts → renal pelvis → ureter → urinary bladder → urethra
→ outside body.
4. Out of 180 L of filtrate, about 99 % is reabsorbed and only 1–1.5 L/day is excreted as urine.
5. Normal urine:
Pale yellow in color
Slightly acidic (pH ≈ 6)
Free from protein, sugar, and blood cells
Easy Formula to Remember
7️7️⃣
F – R – S – C – E
??????
→ Filtration – Reabsorption – Secretion – Concentration – EXCRETION
Blood in Renal Artery
↓
Reaches Glomerulus (in Bowman’s Capsule)
↓
Glomerular Filtration
→ Water, glucose, salts, urea filter out
→ Large proteins & blood cells remain
↓
Glomerular Filtrate (Primary Urine)
↓
Tubular Reabsorption
→ Useful substances (glucose, amino acids, Na⁺, H₂O) reabsorbed into blood
↓
Tubular Secretion
→ Extra wastes (H⁺, K⁺, NH₃, drugs) secreted into tubule
↓
Concentration & Dilution
→ Loop of Henle & Vasa Recta = Counter-current mechanism
→ ADH & Aldosterone control water and salt reabsorption
↓
Final Urine Formation
→ Urea, uric acid, creatinine, salts, water
↓
Collecting Duct
↓
Renal Pelvis
↓
Ureter
↓
Urinary Bladder
↓
Urethra
↓
Urine Excreted Outside Body
Physiology of the Skin (Integumentary System)
The skin is the largest organ of the body and performs ten major physiological functions that are
essential for survival and homeostasis.
1. Protection
The skin protects the body against mechanical injury, harmful chemicals, ultraviolet rays, and
microorganisms.
Sebum and sweat form an acid mantle that prevents the growth of bacteria and fungi.
Melanin protects against harmful ultraviolet radiation.
The skin also prevents dehydration by reducing excessive water loss.
2. Thermoregulation
??????️
Tubular Reabsorption
→ Useful substances (glucose, amino acids, Na⁺, H₂O) reabsorbed into blood
↓
Tubular Secretion
→ Extra wastes (H⁺, K⁺, NH₃, drugs) secreted into tubule
↓
Concentration & Dilution
→ Loop of Henle & Vasa Recta = Counter-current mechanism
→ ADH & Aldosterone control water and salt reabsorption
↓
Final Urine Formation
→ Urea, uric acid, creatinine, salts, water
↓
Collecting Duct
↓
Renal Pelvis
↓
Ureter
↓
Urinary Bladder
↓
Urethra
↓
Urine Excreted Outside Body
Physiology of the Skin (Integumentary System)
The skin is the largest organ of the body and performs ten major physiological functions that are
essential for survival and homeostasis.
1. Protection
The skin protects the body against mechanical injury, harmful chemicals, ultraviolet rays, and
microorganisms.
Sebum and sweat form an acid mantle that prevents the growth of bacteria and fungi.
Melanin protects against harmful ultraviolet radiation.
The skin also prevents dehydration by reducing excessive water loss.
2. Thermoregulation
??????️
The skin maintains a constant body temperature of about 37 °C.
In hot conditions, sweat glands produce sweat, which cools the body when it evaporates.
In hot conditions, dermal blood vessels undergo vasodilation, which increases blood flow near
the surface and allows heat to be released.
In cold conditions, blood vessels undergo vasoconstriction, which reduces blood flow to the
surface and conserves heat.
In cold conditions, piloerection or goosebumps occur when arrector pili muscles contract and
cause hair to stand, trapping a thin layer of air that helps in insulation.
In cold conditions, shivering occurs due to muscle contractions, which produce extra heat.
The hypothalamus controls thermoregulation by receiving signals from skin receptors and
initiating appropriate responses.
3. Sensation
??????
The skin contains different receptors that detect external stimuli.
Meissner’s corpuscles detect light touch.
Merkel cells detect fine touch and shape.
Pacinian corpuscles detect deep pressure and vibration.
Thermoreceptors detect hot and cold.
Free nerve endings detect pain.
The mechanism of sensation occurs in four steps:
1. A stimulus such as touch, heat, or pain acts on the skin receptors.
2. The receptors convert the stimulus into an electrical nerve impulse.
3. The impulse travels through sensory nerves to the spinal cord and brain.
4. The brain interprets the signal, leading to the perception of touch, pressure, pain, or temperature.
4. Excretion
Sweat glands excrete small amounts of water, salts, urea, lactic acid, and ammonia.
Although excretion through the skin is minor, it contributes to waste removal and electrolyte balance.
5. Vitamin D Synthesis ☀ ️
Ultraviolet rays from sunlight convert 7-dehydrocholesterol in the skin into Vitamin D3 (cholecalciferol).
In the liver, Vitamin D3 is converted into calcidiol.
In the kidney, it is converted into calcitriol, the active form of Vitamin D.
Calcitriol helps in the absorption of calcium and phosphate, which are required for strong bones and teeth.
6. Immunity
??????️
The epidermis contains Langerhans cells that present antigens to activate immune responses.
Sweat and sebum contain antimicrobial substances such as lysozyme and defensins.
Normal skin flora also protects the body by preventing the growth of harmful microorganisms.
In hot conditions, sweat glands produce sweat, which cools the body when it evaporates.
In hot conditions, dermal blood vessels undergo vasodilation, which increases blood flow near
the surface and allows heat to be released.
In cold conditions, blood vessels undergo vasoconstriction, which reduces blood flow to the
surface and conserves heat.
In cold conditions, piloerection or goosebumps occur when arrector pili muscles contract and
cause hair to stand, trapping a thin layer of air that helps in insulation.
In cold conditions, shivering occurs due to muscle contractions, which produce extra heat.
The hypothalamus controls thermoregulation by receiving signals from skin receptors and
initiating appropriate responses.
3. Sensation
??????
The skin contains different receptors that detect external stimuli.
Meissner’s corpuscles detect light touch.
Merkel cells detect fine touch and shape.
Pacinian corpuscles detect deep pressure and vibration.
Thermoreceptors detect hot and cold.
Free nerve endings detect pain.
The mechanism of sensation occurs in four steps:
1. A stimulus such as touch, heat, or pain acts on the skin receptors.
2. The receptors convert the stimulus into an electrical nerve impulse.
3. The impulse travels through sensory nerves to the spinal cord and brain.
4. The brain interprets the signal, leading to the perception of touch, pressure, pain, or temperature.
4. Excretion
Sweat glands excrete small amounts of water, salts, urea, lactic acid, and ammonia.
Although excretion through the skin is minor, it contributes to waste removal and electrolyte balance.
5. Vitamin D Synthesis ☀ ️
Ultraviolet rays from sunlight convert 7-dehydrocholesterol in the skin into Vitamin D3 (cholecalciferol).
In the liver, Vitamin D3 is converted into calcidiol.
In the kidney, it is converted into calcitriol, the active form of Vitamin D.
Calcitriol helps in the absorption of calcium and phosphate, which are required for strong bones and teeth.
6. Immunity
??????️
The epidermis contains Langerhans cells that present antigens to activate immune responses.
Sweat and sebum contain antimicrobial substances such as lysozyme and defensins.
Normal skin flora also protects the body by preventing the growth of harmful microorganisms.
7. Regeneration / Healing
The skin heals itself after injury through four stages.
In the hemostasis stage, a clot forms to stop bleeding.
In the inflammation stage, immune cells clear debris and pathogens.
In the proliferation stage, fibroblasts, keratinocytes, and capillaries help form new tissue.
In the remodeling stage, scar tissue forms and strengthens the repaired area.
8. Secretion
Sebaceous glands secrete sebum, which lubricates the skin and hair and prevents dryness.
Eccrine sweat glands secrete watery sweat that helps in cooling the body.
Apocrine sweat glands secrete thicker sweat during stress and emotional states.
9. Storage
The skin stores fat in the hypodermis, which serves as an energy reserve.
The skin stores water and electrolytes.
The skin also holds about 5–10% of the body’s blood volume, which can be redirected in
emergencies.
10. Communication / Social Role
The skin reflects emotions such as blushing during embarrassment, pallor during fear, and
sweating during stress.
The skin shows health conditions such as jaundice (yellowish skin), cyanosis (bluish skin), and rashes.
The skin also helps in non-verbal communication and social interaction through facial
expressions and color changes.
FOOD INTAKE (Ingestion)
↓
MOUTH
→ Chewing of food (Mastication)
→ Mixing with saliva
→ Salivary amylase acts on starch → Maltose
↓
PHARYNX & ESOPHAGUS
→ Swallowing of food (Deglutition)
The skin heals itself after injury through four stages.
In the hemostasis stage, a clot forms to stop bleeding.
In the inflammation stage, immune cells clear debris and pathogens.
In the proliferation stage, fibroblasts, keratinocytes, and capillaries help form new tissue.
In the remodeling stage, scar tissue forms and strengthens the repaired area.
8. Secretion
Sebaceous glands secrete sebum, which lubricates the skin and hair and prevents dryness.
Eccrine sweat glands secrete watery sweat that helps in cooling the body.
Apocrine sweat glands secrete thicker sweat during stress and emotional states.
9. Storage
The skin stores fat in the hypodermis, which serves as an energy reserve.
The skin stores water and electrolytes.
The skin also holds about 5–10% of the body’s blood volume, which can be redirected in
emergencies.
10. Communication / Social Role
The skin reflects emotions such as blushing during embarrassment, pallor during fear, and
sweating during stress.
The skin shows health conditions such as jaundice (yellowish skin), cyanosis (bluish skin), and rashes.
The skin also helps in non-verbal communication and social interaction through facial
expressions and color changes.
FOOD INTAKE (Ingestion)
↓
MOUTH
→ Chewing of food (Mastication)
→ Mixing with saliva
→ Salivary amylase acts on starch → Maltose
↓
PHARYNX & ESOPHAGUS
→ Swallowing of food (Deglutition)
→ Peristaltic movement pushes food to stomach
↓
STOMACH
→ Gastric juice (HCl + Pepsin)
→ Proteins → Peptones
→ Food converted to semi-liquid chyme
↓
SMALL INTESTINE
→ Receives bile (from liver) & pancreatic juice (from pancreas)
→ Bile emulsifies fats
→ Pancreatic enzymes act:
• Amylase → Starch → Maltose
• Trypsin → Peptones → Amino acids
• Lipase → Fats → Fatty acids + Glycerol
→ Intestinal enzymes act:
• Maltase → Maltose → Glucose
• Sucrase → Sucrose → Glucose + Fructose
• Lactase → Lactose → Glucose + Galactose
→ Digestion completed
→ Absorption of nutrients through villi into blood & lymph
↓
LARGE INTESTINE
→ Absorption of water and electrolytes
→ Formation of feces
↓
RECTUM & ANUS
→ Storage and excretion of feces (Defecation)
?????? Physiology of Digestive System
1
️
⃣ Ingestion – Mouth
1. Digestion begins in the mouth, where food is taken in — this process is called ingestion.
2. The teeth chew and grind the food into smaller pieces; this is known as mastication.
3. Salivary glands present in the mouth secrete saliva, which softens the food and helps in swallowing.
4. Saliva contains an enzyme called salivary amylase (ptyalin), which starts the digestion of starch and
converts it into a simpler sugar called maltose.
5. The tongue mixes food with saliva and helps in forming a soft mass called bolus that can be easily
swallowed.
↓
STOMACH
→ Gastric juice (HCl + Pepsin)
→ Proteins → Peptones
→ Food converted to semi-liquid chyme
↓
SMALL INTESTINE
→ Receives bile (from liver) & pancreatic juice (from pancreas)
→ Bile emulsifies fats
→ Pancreatic enzymes act:
• Amylase → Starch → Maltose
• Trypsin → Peptones → Amino acids
• Lipase → Fats → Fatty acids + Glycerol
→ Intestinal enzymes act:
• Maltase → Maltose → Glucose
• Sucrase → Sucrose → Glucose + Fructose
• Lactase → Lactose → Glucose + Galactose
→ Digestion completed
→ Absorption of nutrients through villi into blood & lymph
↓
LARGE INTESTINE
→ Absorption of water and electrolytes
→ Formation of feces
↓
RECTUM & ANUS
→ Storage and excretion of feces (Defecation)
?????? Physiology of Digestive System
1
️
⃣ Ingestion – Mouth
1. Digestion begins in the mouth, where food is taken in — this process is called ingestion.
2. The teeth chew and grind the food into smaller pieces; this is known as mastication.
3. Salivary glands present in the mouth secrete saliva, which softens the food and helps in swallowing.
4. Saliva contains an enzyme called salivary amylase (ptyalin), which starts the digestion of starch and
converts it into a simpler sugar called maltose.
5. The tongue mixes food with saliva and helps in forming a soft mass called bolus that can be easily
swallowed.
2
️
⃣ Propulsion – Pharynx and Esophagus
1. The pharynx is the part of the throat that connects the mouth to the esophagus.
2. During swallowing (deglutition), the bolus passes from the mouth through the pharynx into the esophagus.
3. The epiglottis closes the windpipe during swallowing to prevent food from entering the respiratory tract.
4. The esophagus pushes food toward the stomach through rhythmic, wave-like muscular contractions
known as peristalsis.
3
️
⃣ Digestion in the Stomach
1. The stomach acts as a temporary storage organ for food.
2. The inner lining of the stomach secretes gastric juice, which contains three important substances:
Hydrochloric acid (HCl) that kills bacteria and activates the enzyme pepsinogen.
Pepsin, which breaks down proteins into smaller substances called peptones.
Mucus, which protects the stomach wall from acid.
3. The food is churned and mixed with gastric juice to form a semi-liquid substance called chyme.
4. Partial digestion of proteins takes place in the stomach.
4
️
⃣ Digestion in the Small Intestine
1. The small intestine is the longest part of the digestive tract and the main site of digestion and absorption.
2. The chyme coming from the stomach mixes with three digestive juices — bile, pancreatic juice, and
intestinal juice.
3. Bile, which is produced by the liver and stored in the gallbladder, contains bile salts that emulsify fats,
breaking large fat globules into smaller droplets.
4. Pancreatic juice is secreted by the pancreas and contains three main enzymes:
Amylase, which acts on starch and converts it into maltose.
Trypsin, which acts on proteins and converts them into amino acids.
Lipase, which acts on fats and converts them into fatty acids and glycerol.
5. Intestinal juice (also called succus entericus) is secreted by the glands of the small intestine and completes
the digestion process with the following enzymes:
Maltase, which breaks maltose into two molecules of glucose.
Sucrase, which breaks sucrose into glucose and fructose.
Lactase, which breaks lactose into glucose and galactose.
6. After these actions, food is completely digested and converted into simple forms such as glucose, amino
acids, fatty acids, and glycerol.
5
️
⃣ Absorption of Nutrients
1. Absorption mainly takes place in the small intestine.
2. The inner lining of the small intestine has many finger-like projections called villi, which increase the
surface area for absorption.
3. Glucose and amino acids pass into the blood capillaries of the villi.
4. Fatty acids and glycerol are absorbed into small lymph vessels called lacteals.
️
⃣ Propulsion – Pharynx and Esophagus
1. The pharynx is the part of the throat that connects the mouth to the esophagus.
2. During swallowing (deglutition), the bolus passes from the mouth through the pharynx into the esophagus.
3. The epiglottis closes the windpipe during swallowing to prevent food from entering the respiratory tract.
4. The esophagus pushes food toward the stomach through rhythmic, wave-like muscular contractions
known as peristalsis.
3
️
⃣ Digestion in the Stomach
1. The stomach acts as a temporary storage organ for food.
2. The inner lining of the stomach secretes gastric juice, which contains three important substances:
Hydrochloric acid (HCl) that kills bacteria and activates the enzyme pepsinogen.
Pepsin, which breaks down proteins into smaller substances called peptones.
Mucus, which protects the stomach wall from acid.
3. The food is churned and mixed with gastric juice to form a semi-liquid substance called chyme.
4. Partial digestion of proteins takes place in the stomach.
4
️
⃣ Digestion in the Small Intestine
1. The small intestine is the longest part of the digestive tract and the main site of digestion and absorption.
2. The chyme coming from the stomach mixes with three digestive juices — bile, pancreatic juice, and
intestinal juice.
3. Bile, which is produced by the liver and stored in the gallbladder, contains bile salts that emulsify fats,
breaking large fat globules into smaller droplets.
4. Pancreatic juice is secreted by the pancreas and contains three main enzymes:
Amylase, which acts on starch and converts it into maltose.
Trypsin, which acts on proteins and converts them into amino acids.
Lipase, which acts on fats and converts them into fatty acids and glycerol.
5. Intestinal juice (also called succus entericus) is secreted by the glands of the small intestine and completes
the digestion process with the following enzymes:
Maltase, which breaks maltose into two molecules of glucose.
Sucrase, which breaks sucrose into glucose and fructose.
Lactase, which breaks lactose into glucose and galactose.
6. After these actions, food is completely digested and converted into simple forms such as glucose, amino
acids, fatty acids, and glycerol.
5
️
⃣ Absorption of Nutrients
1. Absorption mainly takes place in the small intestine.
2. The inner lining of the small intestine has many finger-like projections called villi, which increase the
surface area for absorption.
3. Glucose and amino acids pass into the blood capillaries of the villi.
4. Fatty acids and glycerol are absorbed into small lymph vessels called lacteals.
5. These absorbed nutrients are then carried to different parts of the body through the bloodstream for energy
and growth.
6
️
⃣ Large Intestine – Formation of Feces
1. The remaining undigested food passes into the large intestine.
2. In the large intestine, water and electrolytes are absorbed back into the body.
3. The friendly bacteria present in the colon help in partial digestion and produce some vitamins such as
vitamin K.
4. The leftover waste materials become semi-solid and are converted into feces.
7
️
⃣ Defecation – Rectum and Anus
1. The rectum acts as a temporary storage area for feces.
2. When the rectum is full, nerve signals trigger the urge to defecate.
3. The anus controls the expulsion of feces through voluntary and involuntary muscles.
4. The process of removing waste from the body is called defecation, which completes digestion.
8
️
⃣ Summary of the Flow
Mouth → Pharynx → Esophagus → Stomach → Small Intestine → Large Intestine → Rectum → Anus
Main Processes:
Ingestion → Propulsion → Digestion → Absorption → Defecation
9
️
⃣ Key Points to Remember
1. Digestion starts in the mouth and ends in the small intestine.
2. Bile helps in fat digestion but contains no enzyme.
3. Most absorption occurs in the small intestine, while water absorption occurs in the large intestine.
4. The entire process is controlled by both nervous and hormonal mechanisms for coordination.
?????? Physiology of Menstrual Cycle
1
️
⃣ Introduction
1. The menstrual cycle is a natural, regular process that occurs in females between menarche and
menopause.
2. It prepares the female body every month for possible fertilization and pregnancy.
3. The cycle involves rhythmic changes in the ovaries, uterus, hormones, and endometrium.
4. The average length of the menstrual cycle is 28 days, but it may range from 21 to 35 days.
2
️
⃣ Definition
1. The menstrual cycle is the sequence of cyclic changes that occur in the female reproductive organs under
the influence of hormones from the pituitary gland and ovaries.
and growth.
6
️
⃣ Large Intestine – Formation of Feces
1. The remaining undigested food passes into the large intestine.
2. In the large intestine, water and electrolytes are absorbed back into the body.
3. The friendly bacteria present in the colon help in partial digestion and produce some vitamins such as
vitamin K.
4. The leftover waste materials become semi-solid and are converted into feces.
7
️
⃣ Defecation – Rectum and Anus
1. The rectum acts as a temporary storage area for feces.
2. When the rectum is full, nerve signals trigger the urge to defecate.
3. The anus controls the expulsion of feces through voluntary and involuntary muscles.
4. The process of removing waste from the body is called defecation, which completes digestion.
8
️
⃣ Summary of the Flow
Mouth → Pharynx → Esophagus → Stomach → Small Intestine → Large Intestine → Rectum → Anus
Main Processes:
Ingestion → Propulsion → Digestion → Absorption → Defecation
9
️
⃣ Key Points to Remember
1. Digestion starts in the mouth and ends in the small intestine.
2. Bile helps in fat digestion but contains no enzyme.
3. Most absorption occurs in the small intestine, while water absorption occurs in the large intestine.
4. The entire process is controlled by both nervous and hormonal mechanisms for coordination.
?????? Physiology of Menstrual Cycle
1
️
⃣ Introduction
1. The menstrual cycle is a natural, regular process that occurs in females between menarche and
menopause.
2. It prepares the female body every month for possible fertilization and pregnancy.
3. The cycle involves rhythmic changes in the ovaries, uterus, hormones, and endometrium.
4. The average length of the menstrual cycle is 28 days, but it may range from 21 to 35 days.
2
️
⃣ Definition
1. The menstrual cycle is the sequence of cyclic changes that occur in the female reproductive organs under
the influence of hormones from the pituitary gland and ovaries.
2. These changes lead to ovulation and menstruation in a regular pattern.
3
️
⃣ Duration
1. One complete menstrual cycle takes about 28 ± 2 days.
2. The first day of menstrual bleeding is counted as Day 1 of the new cycle.
3. The menstrual flow usually lasts for 3 to 5 days, with a blood loss of about 30 to 80 mL.
4
️
⃣ Main Phases of the Menstrual Cycle
The cycle is divided into four main phases:
1. Menstrual Phase (Days 1–5)
2. Follicular or Proliferative Phase (Days 6–14)
3. Ovulatory Phase (Around Day 14)
4. Luteal or Secretory Phase (Days 15–28)
5
️
⃣ Menstrual Phase (Days 1–5)
1. This phase starts when the corpus luteum from the previous cycle degenerates.
2. The fall in estrogen and progesterone levels causes the endometrium to break down.
3. The functional layer of the endometrium is shed as menstrual bleeding.
4. The discharge contains blood, tissue fragments, mucus, and epithelial cells.
5. The ovaries contain developing follicles that are stimulated by FSH.
6
️
⃣ Follicular / Proliferative Phase (Days 6–14)
1. The anterior pituitary gland secretes FSH (Follicle-Stimulating Hormone).
2. FSH stimulates several ovarian follicles to grow; one becomes the dominant Graafian follicle.
3. The growing follicle secretes estrogen.
4. Estrogen causes the endometrium to thicken and repair after menstruation.
5. Uterine glands and blood vessels grow rapidly, preparing the uterus for possible implantation.
6. Near Day 14, there is a sudden rise (surge) in LH (Luteinizing Hormone), which triggers ovulation.
7
️
⃣ Ovulatory Phase (Around Day 14)
1. The LH surge causes the mature Graafian follicle to rupture.
2. The ovum (egg) is released from the ovary into the fallopian tube.
3. The ovum remains viable for 12–24 hours and may be fertilized if sperm are present.
4. After ovulation, the ruptured follicle transforms into a yellow body called the corpus luteum.
8
️
⃣ Luteal / Secretory Phase (Days 15–28)
1. The corpus luteum secretes large amounts of progesterone and some estrogen.
2. Progesterone makes the endometrium soft, thick, and glandular to receive a fertilized ovum.
3. The uterine glands coil and secrete glycogen and nutrients for nourishment.
4. If fertilization occurs, the corpus luteum continues to function and supports the early pregnancy.
5. If fertilization does not occur, the corpus luteum degenerates into the corpus albicans.
3
️
⃣ Duration
1. One complete menstrual cycle takes about 28 ± 2 days.
2. The first day of menstrual bleeding is counted as Day 1 of the new cycle.
3. The menstrual flow usually lasts for 3 to 5 days, with a blood loss of about 30 to 80 mL.
4
️
⃣ Main Phases of the Menstrual Cycle
The cycle is divided into four main phases:
1. Menstrual Phase (Days 1–5)
2. Follicular or Proliferative Phase (Days 6–14)
3. Ovulatory Phase (Around Day 14)
4. Luteal or Secretory Phase (Days 15–28)
5
️
⃣ Menstrual Phase (Days 1–5)
1. This phase starts when the corpus luteum from the previous cycle degenerates.
2. The fall in estrogen and progesterone levels causes the endometrium to break down.
3. The functional layer of the endometrium is shed as menstrual bleeding.
4. The discharge contains blood, tissue fragments, mucus, and epithelial cells.
5. The ovaries contain developing follicles that are stimulated by FSH.
6
️
⃣ Follicular / Proliferative Phase (Days 6–14)
1. The anterior pituitary gland secretes FSH (Follicle-Stimulating Hormone).
2. FSH stimulates several ovarian follicles to grow; one becomes the dominant Graafian follicle.
3. The growing follicle secretes estrogen.
4. Estrogen causes the endometrium to thicken and repair after menstruation.
5. Uterine glands and blood vessels grow rapidly, preparing the uterus for possible implantation.
6. Near Day 14, there is a sudden rise (surge) in LH (Luteinizing Hormone), which triggers ovulation.
7
️
⃣ Ovulatory Phase (Around Day 14)
1. The LH surge causes the mature Graafian follicle to rupture.
2. The ovum (egg) is released from the ovary into the fallopian tube.
3. The ovum remains viable for 12–24 hours and may be fertilized if sperm are present.
4. After ovulation, the ruptured follicle transforms into a yellow body called the corpus luteum.
8
️
⃣ Luteal / Secretory Phase (Days 15–28)
1. The corpus luteum secretes large amounts of progesterone and some estrogen.
2. Progesterone makes the endometrium soft, thick, and glandular to receive a fertilized ovum.
3. The uterine glands coil and secrete glycogen and nutrients for nourishment.
4. If fertilization occurs, the corpus luteum continues to function and supports the early pregnancy.
5. If fertilization does not occur, the corpus luteum degenerates into the corpus albicans.
6. The fall in progesterone and estrogen levels causes endometrial breakdown, starting the next menstrual
phase.
9
️
⃣ Hormonal Regulation (HPO Axis)
1. The hypothalamus releases GnRH (Gonadotropin-Releasing Hormone).
2. GnRH stimulates the anterior pituitary to secrete FSH and LH.
3. FSH helps in the growth and maturation of ovarian follicles.
4. LH causes ovulation and formation of the corpus luteum.
5. The ovaries secrete estrogen and progesterone to act on the uterus.
6. These hormones regulate the menstrual, proliferative, and secretory changes in the endometrium.
7. The cycle follows a feedback mechanism —
High estrogen before ovulation → increases LH (positive feedback).
High progesterone after ovulation → inhibits FSH & LH (negative feedback).
?????? Endometrial Changes (During Each Phase)
1. Menstrual Phase: The functional layer is shed due to fall in hormones.
2. Proliferative Phase: The endometrium becomes thicker under estrogen influence.
3. Secretory Phase: The glands coil and secrete nutrients under progesterone influence.
4. Premenstrual Phase: If no fertilization occurs, the lining degenerates and bleeding starts.
11
️
⃣ If Fertilization Occurs
1. The fertilized ovum travels to the uterus and implants in the endometrium.
2. The corpus luteum continues to secrete progesterone to maintain pregnancy.
3. Menstruation stops during pregnancy.
12
️
⃣ If Fertilization Does Not Occur
1. The corpus luteum degenerates and forms corpus albicans.
2. Levels of estrogen and progesterone fall sharply.
3. The endometrium breaks down and is shed as menstrual bleeding.
4. A new menstrual cycle begins.
13
️
⃣ Common Symptoms During Menstrual Cycle
1. Vaginal bleeding lasting 3–5 days.
2. Lower abdominal cramps and back pain.
3. Bloating and heaviness in the stomach.
4. Fatigue, irritability, and mood changes.
5. Headache or mild nausea in some women.
14
️
⃣ Significance / Importance
1. The menstrual cycle prepares the uterus for pregnancy each month.
2. It ensures the release of a mature ovum for fertilization.
3. It maintains reproductive and hormonal health in women.
phase.
9
️
⃣ Hormonal Regulation (HPO Axis)
1. The hypothalamus releases GnRH (Gonadotropin-Releasing Hormone).
2. GnRH stimulates the anterior pituitary to secrete FSH and LH.
3. FSH helps in the growth and maturation of ovarian follicles.
4. LH causes ovulation and formation of the corpus luteum.
5. The ovaries secrete estrogen and progesterone to act on the uterus.
6. These hormones regulate the menstrual, proliferative, and secretory changes in the endometrium.
7. The cycle follows a feedback mechanism —
High estrogen before ovulation → increases LH (positive feedback).
High progesterone after ovulation → inhibits FSH & LH (negative feedback).
?????? Endometrial Changes (During Each Phase)
1. Menstrual Phase: The functional layer is shed due to fall in hormones.
2. Proliferative Phase: The endometrium becomes thicker under estrogen influence.
3. Secretory Phase: The glands coil and secrete nutrients under progesterone influence.
4. Premenstrual Phase: If no fertilization occurs, the lining degenerates and bleeding starts.
11
️
⃣ If Fertilization Occurs
1. The fertilized ovum travels to the uterus and implants in the endometrium.
2. The corpus luteum continues to secrete progesterone to maintain pregnancy.
3. Menstruation stops during pregnancy.
12
️
⃣ If Fertilization Does Not Occur
1. The corpus luteum degenerates and forms corpus albicans.
2. Levels of estrogen and progesterone fall sharply.
3. The endometrium breaks down and is shed as menstrual bleeding.
4. A new menstrual cycle begins.
13
️
⃣ Common Symptoms During Menstrual Cycle
1. Vaginal bleeding lasting 3–5 days.
2. Lower abdominal cramps and back pain.
3. Bloating and heaviness in the stomach.
4. Fatigue, irritability, and mood changes.
5. Headache or mild nausea in some women.
14
️
⃣ Significance / Importance
1. The menstrual cycle prepares the uterus for pregnancy each month.
2. It ensures the release of a mature ovum for fertilization.
3. It maintains reproductive and hormonal health in women.
4. Regular cycles indicate normal hormonal balance.
5. Irregular or painful cycles may suggest hormonal imbalance or disease.
15
️
⃣ Flow of Events (Summary)
Hypothalamus → GnRH → Pituitary → FSH & LH
→ Ovary → Follicle Growth → Estrogen ↑ → Endometrial Repair
→ LH Surge → Ovulation → Corpus Luteum → Progesterone ↑
→ Endometrium Ready for Implantation
→ If No Fertilization → Hormones Fall → Menstruation Begins → New Cycle
16
️
⃣ Summary of Phases (In Simple Words)
Menstrual Phase: Bleeding due to hormone fall.
Follicular Phase: Follicle grows and endometrium repairs.
Ovulatory Phase: Egg is released from ovary.
Luteal Phase: Uterus prepared for implantation.
If no pregnancy: Hormones fall, menstruation restarts.
17
️
⃣ Summary Flow
Menstrual Phase → Follicular Phase → Ovulation → Luteal Phase → Menstruation
18
️
⃣ Key Hormones Involved
GnRH – from hypothalamus.
FSH – grows ovarian follicles.
LH – causes ovulation and corpus luteum formation.
Estrogen – repairs and thickens endometrium.
Progesterone – maintains endometrium for implantation.
19
️
⃣ Duration Summary
One complete menstrual cycle = 28 days.
Menstrual flow = 3–5 days.
Ovulation = Day 14 (average).
Secretory phase = Day 15–28.
20
️
⃣ Final Summary (In One Line)
The menstrual cycle is a monthly rhythmic process controlled by hormones, where the uterus prepares for
pregnancy, and if pregnancy does not occur, the lining is shed as menstruation, repeating every 28 days.
Flow Chart – Physiology of Menstrual Cycle
?????? Hypothalamus
↓
Releases GnRH (Gonadotropin-Releasing Hormone)
↓
?????? Anterior Pituitary Gland
5. Irregular or painful cycles may suggest hormonal imbalance or disease.
15
️
⃣ Flow of Events (Summary)
Hypothalamus → GnRH → Pituitary → FSH & LH
→ Ovary → Follicle Growth → Estrogen ↑ → Endometrial Repair
→ LH Surge → Ovulation → Corpus Luteum → Progesterone ↑
→ Endometrium Ready for Implantation
→ If No Fertilization → Hormones Fall → Menstruation Begins → New Cycle
16
️
⃣ Summary of Phases (In Simple Words)
Menstrual Phase: Bleeding due to hormone fall.
Follicular Phase: Follicle grows and endometrium repairs.
Ovulatory Phase: Egg is released from ovary.
Luteal Phase: Uterus prepared for implantation.
If no pregnancy: Hormones fall, menstruation restarts.
17
️
⃣ Summary Flow
Menstrual Phase → Follicular Phase → Ovulation → Luteal Phase → Menstruation
18
️
⃣ Key Hormones Involved
GnRH – from hypothalamus.
FSH – grows ovarian follicles.
LH – causes ovulation and corpus luteum formation.
Estrogen – repairs and thickens endometrium.
Progesterone – maintains endometrium for implantation.
19
️
⃣ Duration Summary
One complete menstrual cycle = 28 days.
Menstrual flow = 3–5 days.
Ovulation = Day 14 (average).
Secretory phase = Day 15–28.
20
️
⃣ Final Summary (In One Line)
The menstrual cycle is a monthly rhythmic process controlled by hormones, where the uterus prepares for
pregnancy, and if pregnancy does not occur, the lining is shed as menstruation, repeating every 28 days.
Flow Chart – Physiology of Menstrual Cycle
?????? Hypothalamus
↓
Releases GnRH (Gonadotropin-Releasing Hormone)
↓
?????? Anterior Pituitary Gland
↓
Stimulated by GnRH → secretes two hormones:
• FSH (Follicle-Stimulating Hormone)
• LH (Luteinizing Hormone)
↓
?????? Ovary
↓
Under FSH and LH influence:
• Follicle grows and matures
• Maturing follicle secretes Estrogen
↓
?????? Uterus – Phase 1: Menstrual Phase (Day 1–5)
• Fall in Estrogen & Progesterone → endometrium breaks down
• Shedding of functional layer (menstrual bleeding)
• Blood loss: 30–80 mL
↓
?????? Uterus – Phase 2: Follicular / Proliferative Phase (Day 6–14)
• FSH promotes follicle growth in ovary
• Follicle secretes Estrogen → endometrium thickens
• Blood vessels and glands increase
• Endometrium regenerates after menstruation
• LH secretion increases (LH surge near Day 14)
↓
?????? Ovary – Ovulatory Phase (Around Day 14)
• LH surge → mature Graafian follicle ruptures
• Ovum (egg) released into fallopian tube = Ovulation
• Best time for fertilization
• Ruptured follicle converts into Corpus Luteum
↓
?????? Uterus – Phase 3: Luteal / Secretory Phase (Day 15–28)
• Corpus luteum secretes Progesterone + small amount of Estrogen
• Progesterone maintains thick, secretory endometrium
• Endometrial glands secrete nutrients for implantation
↓
?????? If Fertilization Occurs
• Fertilized ovum implants in uterus
• Corpus luteum continues to secrete Progesterone
• Pregnancy maintained → Menstruation stops
↓
Stimulated by GnRH → secretes two hormones:
• FSH (Follicle-Stimulating Hormone)
• LH (Luteinizing Hormone)
↓
?????? Ovary
↓
Under FSH and LH influence:
• Follicle grows and matures
• Maturing follicle secretes Estrogen
↓
?????? Uterus – Phase 1: Menstrual Phase (Day 1–5)
• Fall in Estrogen & Progesterone → endometrium breaks down
• Shedding of functional layer (menstrual bleeding)
• Blood loss: 30–80 mL
↓
?????? Uterus – Phase 2: Follicular / Proliferative Phase (Day 6–14)
• FSH promotes follicle growth in ovary
• Follicle secretes Estrogen → endometrium thickens
• Blood vessels and glands increase
• Endometrium regenerates after menstruation
• LH secretion increases (LH surge near Day 14)
↓
?????? Ovary – Ovulatory Phase (Around Day 14)
• LH surge → mature Graafian follicle ruptures
• Ovum (egg) released into fallopian tube = Ovulation
• Best time for fertilization
• Ruptured follicle converts into Corpus Luteum
↓
?????? Uterus – Phase 3: Luteal / Secretory Phase (Day 15–28)
• Corpus luteum secretes Progesterone + small amount of Estrogen
• Progesterone maintains thick, secretory endometrium
• Endometrial glands secrete nutrients for implantation
↓
?????? If Fertilization Occurs
• Fertilized ovum implants in uterus
• Corpus luteum continues to secrete Progesterone
• Pregnancy maintained → Menstruation stops
↓
?????? If Fertilization Does NOT Occur
• Corpus luteum degenerates → forms Corpus Albicans
• Estrogen and Progesterone levels fall
• Endometrium breaks down → Menstrual bleeding begins
↓
?????? New Menstrual Cycle Starts Again
?????? Quick Phase Summary (with Key Hormones)
PhaseDaysMain Hormones Key Events
Menstrual1–5↓ Estrogen, ↓ ProgesteroneEndometrial shedding and bleeding
Follicular / Proliferative6–14↑ FSH, ↑ EstrogenFollicle growth, endometrial repair
Ovulatory~14LH Surge Ovum released from follicle
Luteal / Secretory15–28↑ Progesterone, some EstrogenEndometrium ready for implantation
?????? Simplified Summary Flow (for memory recall)
Hypothalamus (GnRH)
↓
Pituitary (FSH & LH)
↓
Ovary (Estrogen & Progesterone)
↓
Uterus (Menstrual → Proliferative → Secretory Changes)
↓
If No Fertilization → Hormone Fall → Menstrual Phase Repeats
?????? Easy Way to Remember (Mnemonic Style)
“Menstrual → Follicular → Ovulatory → Luteal → Repeat”
?????? Think of it as:
M – Menstrual (Bleeding)
F – Follicular (Repair)
O – Ovulatory (Release)
L – Luteal (Prepare)
Then again → M (Menstrual)
?????? Pulmonary Ventilation (Mechanics of Respiration)
Respiration consists of two main processes:
1
️
⃣ Inhalation (Inspiration) – intake of air into the lungs
2
️
⃣ Exhalation (Expiration) – expulsion of air from the lungs
??????
️
Mechanics of Inhalation
1. Muscular region of diaphragm contracts
2. External intercostal muscles contract
3. Ribs move upward and outward
• Corpus luteum degenerates → forms Corpus Albicans
• Estrogen and Progesterone levels fall
• Endometrium breaks down → Menstrual bleeding begins
↓
?????? New Menstrual Cycle Starts Again
?????? Quick Phase Summary (with Key Hormones)
PhaseDaysMain Hormones Key Events
Menstrual1–5↓ Estrogen, ↓ ProgesteroneEndometrial shedding and bleeding
Follicular / Proliferative6–14↑ FSH, ↑ EstrogenFollicle growth, endometrial repair
Ovulatory~14LH Surge Ovum released from follicle
Luteal / Secretory15–28↑ Progesterone, some EstrogenEndometrium ready for implantation
?????? Simplified Summary Flow (for memory recall)
Hypothalamus (GnRH)
↓
Pituitary (FSH & LH)
↓
Ovary (Estrogen & Progesterone)
↓
Uterus (Menstrual → Proliferative → Secretory Changes)
↓
If No Fertilization → Hormone Fall → Menstrual Phase Repeats
?????? Easy Way to Remember (Mnemonic Style)
“Menstrual → Follicular → Ovulatory → Luteal → Repeat”
?????? Think of it as:
M – Menstrual (Bleeding)
F – Follicular (Repair)
O – Ovulatory (Release)
L – Luteal (Prepare)
Then again → M (Menstrual)
?????? Pulmonary Ventilation (Mechanics of Respiration)
Respiration consists of two main processes:
1
️
⃣ Inhalation (Inspiration) – intake of air into the lungs
2
️
⃣ Exhalation (Expiration) – expulsion of air from the lungs
??????
️
Mechanics of Inhalation
1. Muscular region of diaphragm contracts
2. External intercostal muscles contract
3. Ribs move upward and outward
4. Diaphragm flattens and descends
5. Volume of thoracic cavity increases
6. Pressure around lungs decreases
7. Pressure in alveoli decreases
8. Air enters the lungs
?????? Inhalation is an active process as it requires muscular effort and energy.
Mechanics of Exhalation
1. Muscular region of diaphragm relaxes
2. External intercostal muscles relax
3. Internal intercostal muscles contract
4. Diaphragm returns to dome shape
5. Ribs move downward and inward
6. Volume of thoracic cavity decreases
7. Pressure around lungs increases
8. Pressure in alveoli increases
9. Air leaves the lungs
?????? Exhalation is a passive process as it does not require energy.
4. Respiratory Gas Transport
Meaning
Respiratory gas transport means the carrying of oxygen and carbon dioxide through the blood between the
lungs and body tissues.
A. Oxygen Transport (from Lungs to Tissues)
1. Oxygen enters the blood from the alveoli of the lungs.
2. In the blood, 97% of oxygen combines with hemoglobin in red blood cells.
3. This combination forms oxyhemoglobin (HbO ).
₂
4. The remaining 3% of oxygen dissolves in the plasma.
5. The oxygen-rich blood goes to the left side of the heart.
6. From the heart, it is pumped to all parts of the body through the aorta and arteries.
7. When the blood reaches tissues, the oxygen pressure is low in the cells.
8. So, oxyhemoglobin breaks down and releases oxygen.
9. Oxygen then diffuses from the blood into the tissue cells.
10. The cells use oxygen to produce energy through the process of cellular respiration.
11. After releasing oxygen, hemoglobin becomes reduced hemoglobin (HHb).
12. The blood now becomes deoxygenated and returns to the lungs through veins.
B. Carbon Dioxide Transport (from Tissues to Lungs)
5. Volume of thoracic cavity increases
6. Pressure around lungs decreases
7. Pressure in alveoli decreases
8. Air enters the lungs
?????? Inhalation is an active process as it requires muscular effort and energy.
Mechanics of Exhalation
1. Muscular region of diaphragm relaxes
2. External intercostal muscles relax
3. Internal intercostal muscles contract
4. Diaphragm returns to dome shape
5. Ribs move downward and inward
6. Volume of thoracic cavity decreases
7. Pressure around lungs increases
8. Pressure in alveoli increases
9. Air leaves the lungs
?????? Exhalation is a passive process as it does not require energy.
4. Respiratory Gas Transport
Meaning
Respiratory gas transport means the carrying of oxygen and carbon dioxide through the blood between the
lungs and body tissues.
A. Oxygen Transport (from Lungs to Tissues)
1. Oxygen enters the blood from the alveoli of the lungs.
2. In the blood, 97% of oxygen combines with hemoglobin in red blood cells.
3. This combination forms oxyhemoglobin (HbO ).
₂
4. The remaining 3% of oxygen dissolves in the plasma.
5. The oxygen-rich blood goes to the left side of the heart.
6. From the heart, it is pumped to all parts of the body through the aorta and arteries.
7. When the blood reaches tissues, the oxygen pressure is low in the cells.
8. So, oxyhemoglobin breaks down and releases oxygen.
9. Oxygen then diffuses from the blood into the tissue cells.
10. The cells use oxygen to produce energy through the process of cellular respiration.
11. After releasing oxygen, hemoglobin becomes reduced hemoglobin (HHb).
12. The blood now becomes deoxygenated and returns to the lungs through veins.
B. Carbon Dioxide Transport (from Tissues to Lungs)
1. Carbon dioxide is formed in the tissues as a waste product of energy production.
2. CO moves from the tissue cells into the blood.
₂
3. About 7% of CO is dissolved directly in plasma.
₂
4. About 23% of CO combines with hemoglobin to form carbaminohemoglobin (HbCO ).
₂ ₂
5. About 70% of CO is carried as bicarbonate ions (HCO ) in the plasma.
₂ ₃ ⁻
6. Inside red blood cells, the enzyme carbonic anhydrase helps change CO into carbonic acid (H CO ).
₂ ₂ ₃
7. Carbonic acid then splits into hydrogen ions (H ) and bicarbonate ions (HCO ).
⁺ ₃⁻
8. Bicarbonate ions move out of the red blood cells into the plasma, and chloride ions enter the cell (this is
called chloride shift).
9. The blood carrying CO goes from tissues → veins → right side of the heart → lungs.
₂
10. In the lungs, bicarbonate changes back into CO gas.
₂
11. CO then diffuses from the blood into the alveoli.
₂
12. Finally, CO is removed from the body during exhalation.
₂
C. Summary
Oxygen moves from lungs to tissues.
Carbon dioxide moves from tissues to lungs.
Both gases travel through the blood, mainly with the help of hemoglobin.
This transport maintains the continuous exchange of gases required for life.
2. CO moves from the tissue cells into the blood.
₂
3. About 7% of CO is dissolved directly in plasma.
₂
4. About 23% of CO combines with hemoglobin to form carbaminohemoglobin (HbCO ).
₂ ₂
5. About 70% of CO is carried as bicarbonate ions (HCO ) in the plasma.
₂ ₃ ⁻
6. Inside red blood cells, the enzyme carbonic anhydrase helps change CO into carbonic acid (H CO ).
₂ ₂ ₃
7. Carbonic acid then splits into hydrogen ions (H ) and bicarbonate ions (HCO ).
⁺ ₃⁻
8. Bicarbonate ions move out of the red blood cells into the plasma, and chloride ions enter the cell (this is
called chloride shift).
9. The blood carrying CO goes from tissues → veins → right side of the heart → lungs.
₂
10. In the lungs, bicarbonate changes back into CO gas.
₂
11. CO then diffuses from the blood into the alveoli.
₂
12. Finally, CO is removed from the body during exhalation.
₂
C. Summary
Oxygen moves from lungs to tissues.
Carbon dioxide moves from tissues to lungs.
Both gases travel through the blood, mainly with the help of hemoglobin.
This transport maintains the continuous exchange of gases required for life.
?????? PHYSIOLOGY OF PAIN (MECHANISM OF PAIN)
1
️
⃣ Introduction
1. Pain is a protective function of the nervous system that warns the body of tissue injury or harmful stimuli.
2. It begins with activation of special sensory receptors called nociceptors and ends when the brain perceives
the sensation as pain.
3. The entire process is called nociception, and it involves a chain of four major steps — stimulation,
transmission, perception, and modulation.
2
️
⃣ Definition
Pain is an unpleasant sensory and emotional experience produced when nerve endings are stimulated by
harmful mechanical, thermal, or chemical agents, and the signal travels through nerves to the brain.
3
️
⃣ Steps in the Physiology (Mechanism) of Pain
Step 1 – Stimulation (Activation of Pain Receptors)
1. When tissues are injured, they release chemical substances such as:
– Bradykinin
– Prostaglandins
– Histamine
– Serotonin
– Potassium ions
2. These chemicals stimulate the free nerve endings (nociceptors) present in the skin, muscles, joints, and
viscera.
3. The stimulus is converted into an electrical impulse (action potential) in the sensory nerve.
Step 2 – Transmission (Pain Pathway to Spinal Cord)
1. The electrical impulse travels along afferent nerve fibers:
A-delta fibers: transmit sharp, well-localized pain (fast).
C fibers: transmit dull, aching, or burning pain (slow).
2. These fibers enter the dorsal horn of the spinal cord.
3. Here, the first-order neuron releases neurotransmitters such as Substance P and Glutamate to activate the
second-order neuron.
Step 3 – Ascending Pathway (Transmission to Brain)
1. The second-order neuron crosses to the opposite side of the spinal cord.
2. It ascends through the lateral spinothalamic tract to reach the thalamus in the brain.
3. The thalamus acts as a relay station, sending the signal further to the somatosensory cortex (in the parietal
lobe).
Step 4 – Perception (Awareness of Pain)
1. The third-order neuron carries the impulse from the thalamus to the cerebral cortex.
2. The cortex identifies where the pain is, how strong it is, and what type it is (sharp, dull, burning).
1
️
⃣ Introduction
1. Pain is a protective function of the nervous system that warns the body of tissue injury or harmful stimuli.
2. It begins with activation of special sensory receptors called nociceptors and ends when the brain perceives
the sensation as pain.
3. The entire process is called nociception, and it involves a chain of four major steps — stimulation,
transmission, perception, and modulation.
2
️
⃣ Definition
Pain is an unpleasant sensory and emotional experience produced when nerve endings are stimulated by
harmful mechanical, thermal, or chemical agents, and the signal travels through nerves to the brain.
3
️
⃣ Steps in the Physiology (Mechanism) of Pain
Step 1 – Stimulation (Activation of Pain Receptors)
1. When tissues are injured, they release chemical substances such as:
– Bradykinin
– Prostaglandins
– Histamine
– Serotonin
– Potassium ions
2. These chemicals stimulate the free nerve endings (nociceptors) present in the skin, muscles, joints, and
viscera.
3. The stimulus is converted into an electrical impulse (action potential) in the sensory nerve.
Step 2 – Transmission (Pain Pathway to Spinal Cord)
1. The electrical impulse travels along afferent nerve fibers:
A-delta fibers: transmit sharp, well-localized pain (fast).
C fibers: transmit dull, aching, or burning pain (slow).
2. These fibers enter the dorsal horn of the spinal cord.
3. Here, the first-order neuron releases neurotransmitters such as Substance P and Glutamate to activate the
second-order neuron.
Step 3 – Ascending Pathway (Transmission to Brain)
1. The second-order neuron crosses to the opposite side of the spinal cord.
2. It ascends through the lateral spinothalamic tract to reach the thalamus in the brain.
3. The thalamus acts as a relay station, sending the signal further to the somatosensory cortex (in the parietal
lobe).
Step 4 – Perception (Awareness of Pain)
1. The third-order neuron carries the impulse from the thalamus to the cerebral cortex.
2. The cortex identifies where the pain is, how strong it is, and what type it is (sharp, dull, burning).
3. At this stage, the pain becomes a conscious experience.
Step 5 – Modulation (Control or Inhibition of Pain)
1. The brain can increase or decrease pain perception through descending pathways.
2. The midbrain and medulla release endorphins and enkephalins, which inhibit pain signals in the spinal
cord.
3. This natural suppression system helps in pain control during stress or shock (e.g. a person may not feel
pain immediately after injury).
4
️
⃣ Summary Flow Chart – Mechanism of Pain
Tissue Injury or Harmful Stimulus
↓
Release of Pain-Producing Substances (Bradykinin, Prostaglandin)
↓
Activation of Nociceptors (Free Nerve Endings)
↓
Transmission via A-delta and C Fibers
↓
Synapse in Dorsal Horn (Substance P, Glutamate)
↓
Cross to Opposite Side → Spinothalamic Tract
↓
Thalamus (Relay Station)
↓
Cerebral Cortex → Perception of Pain
↓
Descending Inhibition (Endorphins, Enkephalins)
5
️
⃣ Conclusion
1. The physiology of pain involves a precise sequence of neural events that convert injury into sensation.
2. It begins with stimulation of nociceptors, continues through spinal transmission, and ends with perception
in the brain.
3. The modulation process helps the body naturally reduce pain through inhibitory pathways.
Step 5 – Modulation (Control or Inhibition of Pain)
1. The brain can increase or decrease pain perception through descending pathways.
2. The midbrain and medulla release endorphins and enkephalins, which inhibit pain signals in the spinal
cord.
3. This natural suppression system helps in pain control during stress or shock (e.g. a person may not feel
pain immediately after injury).
4
️
⃣ Summary Flow Chart – Mechanism of Pain
Tissue Injury or Harmful Stimulus
↓
Release of Pain-Producing Substances (Bradykinin, Prostaglandin)
↓
Activation of Nociceptors (Free Nerve Endings)
↓
Transmission via A-delta and C Fibers
↓
Synapse in Dorsal Horn (Substance P, Glutamate)
↓
Cross to Opposite Side → Spinothalamic Tract
↓
Thalamus (Relay Station)
↓
Cerebral Cortex → Perception of Pain
↓
Descending Inhibition (Endorphins, Enkephalins)
5
️
⃣ Conclusion
1. The physiology of pain involves a precise sequence of neural events that convert injury into sensation.
2. It begins with stimulation of nociceptors, continues through spinal transmission, and ends with perception
in the brain.
3. The modulation process helps the body naturally reduce pain through inhibitory pathways.
PHYSIOLOGY OF VISION
1
️
⃣ Introduction
1. The eye is a highly specialized sense organ responsible for vision.
2. It receives light rays, focuses them on the retina, and sends signals to the brain through the optic nerve.
3. The brain and eye work together to form a clear visual image.
2
️
⃣ Light Entry
4. Light rays from an object enter the eye through the cornea.
5. They pass through the aqueous humour, pupil, and lens.
6. The iris controls the amount of light entering the eye.
3
️
⃣ Refraction and Focusing
7. The cornea and lens bend (refract) the incoming light rays.
8. The lens focuses the light rays exactly on the retina.
9. The lens changes its shape to see near and distant objects; this process is called accommodation.
10. A real, small, and inverted image is formed on the retina, mainly on the macula/fovea centralis for clear
vision.
4
️
⃣ Phototransduction
11. The retina contains light-sensitive cells called rods and cones.
12. Rods help in dim-light (black-and-white) vision, and cones help in bright-light (colour) vision.
13. These photoreceptors convert light energy into electrical impulses, a process called phototransduction.
5
️
⃣ Transmission of Impulses
14. The electrical impulses pass from photoreceptors → bipolar cells → ganglion cells.
15. The axons of ganglion cells join together to form the optic nerve.
16. The impulses travel through the optic nerve to the optic chiasma, where some fibres cross to the
opposite side.
17. They continue through the optic tract to reach the thalamus.
18. From the thalamus, the signals are relayed to the visual cortex of the occipital lobe in the brain.
6
️
⃣ Interpretation by the Brain
19. The visual cortex interprets the nerve impulses to form a visual image.
20. The brain corrects the inverted image and perceives the object as upright and meaningful.
21. This interpretation gives us clear and conscious vision.
7
️
⃣ Summary
22. Thus, the cornea and lens act like camera lenses, the retina acts like film, the optic nerve acts like a data
wire, and the brain acts like a computer that interprets what we see.
1
️
⃣ Introduction
1. The eye is a highly specialized sense organ responsible for vision.
2. It receives light rays, focuses them on the retina, and sends signals to the brain through the optic nerve.
3. The brain and eye work together to form a clear visual image.
2
️
⃣ Light Entry
4. Light rays from an object enter the eye through the cornea.
5. They pass through the aqueous humour, pupil, and lens.
6. The iris controls the amount of light entering the eye.
3
️
⃣ Refraction and Focusing
7. The cornea and lens bend (refract) the incoming light rays.
8. The lens focuses the light rays exactly on the retina.
9. The lens changes its shape to see near and distant objects; this process is called accommodation.
10. A real, small, and inverted image is formed on the retina, mainly on the macula/fovea centralis for clear
vision.
4
️
⃣ Phototransduction
11. The retina contains light-sensitive cells called rods and cones.
12. Rods help in dim-light (black-and-white) vision, and cones help in bright-light (colour) vision.
13. These photoreceptors convert light energy into electrical impulses, a process called phototransduction.
5
️
⃣ Transmission of Impulses
14. The electrical impulses pass from photoreceptors → bipolar cells → ganglion cells.
15. The axons of ganglion cells join together to form the optic nerve.
16. The impulses travel through the optic nerve to the optic chiasma, where some fibres cross to the
opposite side.
17. They continue through the optic tract to reach the thalamus.
18. From the thalamus, the signals are relayed to the visual cortex of the occipital lobe in the brain.
6
️
⃣ Interpretation by the Brain
19. The visual cortex interprets the nerve impulses to form a visual image.
20. The brain corrects the inverted image and perceives the object as upright and meaningful.
21. This interpretation gives us clear and conscious vision.
7
️
⃣ Summary
22. Thus, the cornea and lens act like camera lenses, the retina acts like film, the optic nerve acts like a data
wire, and the brain acts like a computer that interprets what we see.
?????? Flow Chart – Physiology of Vision
Light Rays from Object
↓
Enter the Eye through the CORNEA
↓
Pass through AQUEOUS HUMOUR → PUPIL → LENS
↓
IRIS controls the amount of light entering the eye
↓
CORNEA and LENS bend (REFRACT) the light rays
↓
LENS FOCUSES the light rays exactly on the RETINA
↓
RETINA receives a small, real, inverted IMAGE (on the macula)
↓
PHOTORECEPTORS (Rods & Cones) detect the light
↓
Light energy converted into ELECTRICAL IMPULSES (Phototransduction)
↓
Impulses pass → Bipolar Cells → Ganglion Cells
↓
Axons of Ganglion Cells join to form the OPTIC NERVE
↓
OPTIC NERVE carries impulses to the OPTIC CHIASMA
↓
Some fibres cross to the opposite side → form OPTIC TRACT
↓
Impulses reach the THALAMUS
↓
Then travel to the VISUAL CORTEX of the OCCIPITAL LOBE
↓
BRAIN interprets the impulses
↓
Image becomes UPRIGHT and MEANINGFUL
↓
→ FINAL VISION PERCEPTION
Light Rays from Object
↓
Enter the Eye through the CORNEA
↓
Pass through AQUEOUS HUMOUR → PUPIL → LENS
↓
IRIS controls the amount of light entering the eye
↓
CORNEA and LENS bend (REFRACT) the light rays
↓
LENS FOCUSES the light rays exactly on the RETINA
↓
RETINA receives a small, real, inverted IMAGE (on the macula)
↓
PHOTORECEPTORS (Rods & Cones) detect the light
↓
Light energy converted into ELECTRICAL IMPULSES (Phototransduction)
↓
Impulses pass → Bipolar Cells → Ganglion Cells
↓
Axons of Ganglion Cells join to form the OPTIC NERVE
↓
OPTIC NERVE carries impulses to the OPTIC CHIASMA
↓
Some fibres cross to the opposite side → form OPTIC TRACT
↓
Impulses reach the THALAMUS
↓
Then travel to the VISUAL CORTEX of the OCCIPITAL LOBE
↓
BRAIN interprets the impulses
↓
Image becomes UPRIGHT and MEANINGFUL
↓
→ FINAL VISION PERCEPTION
⚙️ PHYSIOLOGY OF CEREBROSPINAL FLUID (CSF)
1
️
⃣ Introduction
Cerebrospinal fluid (CSF) is a vital body fluid that provides both mechanical and metabolic
support to the brain and spinal cord.
It cushions the CNS, maintains its chemical environment, and assists in waste removal.
2
️
⃣ Formation (Secretion Process)
1. Produced by: Choroid plexus (ependymal cells) through active transport of sodium, chloride,
and bicarbonate ions.
2. Mechanism:
Sodium and chloride ions are actively secreted into ventricles.
Water follows osmotically through aquaporin channels.
Carbonic anhydrase enzyme helps regulate ionic exchange.
3. Control:
Sympathetic activity decreases CSF secretion.
Parasympathetic activity increases secretion.
4. Hormonal influence: Changes in blood pH and pressure can alter CSF formation.
3
️
⃣ Circulation and Dynamics
CSF moves in a pulsatile rhythm matching the cardiac cycle.
Flow direction: ventricles → subarachnoid space → arachnoid villi → venous blood.
It circulates unidirectionally within ventricles but multi-directionally in the subarachnoid space.
Average flow rate: ~0.3 mL/min.
4
️
⃣ Composition
ComponentComparison to Plasma
Sodium Slightly higher
Chloride Higher
PotassiumLower
Calcium Lower
Glucose Lower
ProteinVery low (15–40 mg/dL)
Cells0–5 WBC/mm³ (normally none)
1
️
⃣ Introduction
Cerebrospinal fluid (CSF) is a vital body fluid that provides both mechanical and metabolic
support to the brain and spinal cord.
It cushions the CNS, maintains its chemical environment, and assists in waste removal.
2
️
⃣ Formation (Secretion Process)
1. Produced by: Choroid plexus (ependymal cells) through active transport of sodium, chloride,
and bicarbonate ions.
2. Mechanism:
Sodium and chloride ions are actively secreted into ventricles.
Water follows osmotically through aquaporin channels.
Carbonic anhydrase enzyme helps regulate ionic exchange.
3. Control:
Sympathetic activity decreases CSF secretion.
Parasympathetic activity increases secretion.
4. Hormonal influence: Changes in blood pH and pressure can alter CSF formation.
3
️
⃣ Circulation and Dynamics
CSF moves in a pulsatile rhythm matching the cardiac cycle.
Flow direction: ventricles → subarachnoid space → arachnoid villi → venous blood.
It circulates unidirectionally within ventricles but multi-directionally in the subarachnoid space.
Average flow rate: ~0.3 mL/min.
4
️
⃣ Composition
ComponentComparison to Plasma
Sodium Slightly higher
Chloride Higher
PotassiumLower
Calcium Lower
Glucose Lower
ProteinVery low (15–40 mg/dL)
Cells0–5 WBC/mm³ (normally none)
5
️
⃣ Functions
1. Mechanical Protection:
Acts as a shock absorber; reduces effective brain weight from ~1500 g to ~50 g.
2. Homeostasis:
Maintains electrolyte and pH balance for neuron function.
3. Nutrient Supply:
Provides oxygen, glucose, and micronutrients to brain tissues.
4. Waste Removal:
Removes metabolic byproducts and toxins from CNS to venous blood.
5. Temperature Regulation:
Helps maintain stable brain temperature.
6. Circulatory Role:
Assists in distribution of neuroactive substances and hormones.
6
️
⃣ Reabsorption and Pressure Control
Controlled by pressure difference between subarachnoid space and venous sinuses.
High CSF pressure → slows production; low pressure → increases secretion.
Normal CSF pressure: 10–18 cm H O (lying position).
₂
7
️
⃣ Clinical Physiology
Lumbar Puncture Test: Measures CSF pressure or detects infection.
Meningitis: CSF shows increased WBC and protein.
Hydrocephalus: Overproduction or blocked reabsorption causes raised intracranial pressure.
?????? Conclusion
Physiologically, CSF maintains the internal environment of the brain, supports metabolic
functions, and protects the CNS from injury.
Its constant circulation, composition, and pressure balance are essential for healthy neural
activity.
?????? Topic: Physiology of Cerebrospinal Fluid (CSF)
️
⃣ Functions
1. Mechanical Protection:
Acts as a shock absorber; reduces effective brain weight from ~1500 g to ~50 g.
2. Homeostasis:
Maintains electrolyte and pH balance for neuron function.
3. Nutrient Supply:
Provides oxygen, glucose, and micronutrients to brain tissues.
4. Waste Removal:
Removes metabolic byproducts and toxins from CNS to venous blood.
5. Temperature Regulation:
Helps maintain stable brain temperature.
6. Circulatory Role:
Assists in distribution of neuroactive substances and hormones.
6
️
⃣ Reabsorption and Pressure Control
Controlled by pressure difference between subarachnoid space and venous sinuses.
High CSF pressure → slows production; low pressure → increases secretion.
Normal CSF pressure: 10–18 cm H O (lying position).
₂
7
️
⃣ Clinical Physiology
Lumbar Puncture Test: Measures CSF pressure or detects infection.
Meningitis: CSF shows increased WBC and protein.
Hydrocephalus: Overproduction or blocked reabsorption causes raised intracranial pressure.
?????? Conclusion
Physiologically, CSF maintains the internal environment of the brain, supports metabolic
functions, and protects the CNS from injury.
Its constant circulation, composition, and pressure balance are essential for healthy neural
activity.
?????? Topic: Physiology of Cerebrospinal Fluid (CSF)
?????? Formation of CSF
↓
Produced by Choroid Plexus (Ependymal Cells)
↓
Active Secretion of Na , Cl , HCO Ions
⁺ ⁻ ₃⁻
↓
Water Follows Osmotically → CSF Formed
↓
CSF Enters Lateral Ventricles
↓
Flows Through Interventricular Foramen → Third Ventricle
↓
Passes via Cerebral Aqueduct → Fourth Ventricle
↓
Exits Through Median & Lateral Apertures
↓
Circulates in Subarachnoid Space Around Brain & Spinal Cord
↓
Provides:
?????? Mechanical Protection
?????? Nutrient Supply
?????? Waste Removal
?????? Temperature Regulation
↓
Reabsorbed by Arachnoid Villi → Dural Venous Sinuses → Venous Blood
↓
Maintains Constant CSF Volume & Normal Intracranial Pressure
↓
Produced by Choroid Plexus (Ependymal Cells)
↓
Active Secretion of Na , Cl , HCO Ions
⁺ ⁻ ₃⁻
↓
Water Follows Osmotically → CSF Formed
↓
CSF Enters Lateral Ventricles
↓
Flows Through Interventricular Foramen → Third Ventricle
↓
Passes via Cerebral Aqueduct → Fourth Ventricle
↓
Exits Through Median & Lateral Apertures
↓
Circulates in Subarachnoid Space Around Brain & Spinal Cord
↓
Provides:
?????? Mechanical Protection
?????? Nutrient Supply
?????? Waste Removal
?????? Temperature Regulation
↓
Reabsorbed by Arachnoid Villi → Dural Venous Sinuses → Venous Blood
↓
Maintains Constant CSF Volume & Normal Intracranial Pressure
PHYSIOLOGY OF JOINTS – MOVEMENTS AND FUNCTIONS
in your regular teaching-and-exam pattern ??????
?????? Introduction
1. The physiology of joints explains how joints move and how they work together with bones, muscles,
ligaments, and synovial fluid.
2. Movements occur when muscles contract, pulling on bones that act as levers.
3. The synovial fluid and articular cartilage make the movement smooth and friction-free.
?????? Types of Movements at Synovial Joints
1
️
⃣ Gliding Movements
Flat bone surfaces slide over each other.
No angular change.
Example: between carpal bones of the wrist, or tarsal bones of the foot.
2
️
⃣ Angular Movements
Change the angle between two bones.
Flexion: bending, decreases the angle (elbow, knee).
Extension: straightening, increases the angle.
Abduction: movement away from the body’s midline (lifting arm sideways).
Adduction: movement toward the midline.
Circumduction: circular movement combining flexion, extension, abduction, and adduction (arm or leg
circles).
3
️
⃣ Rotational Movements
The bone turns around its own axis.
Medial rotation: toward the body’s midline.
Lateral rotation: away from the midline.
Example: rotation at the shoulder or hip joint.
4
️
⃣ Special Movements
Some joints show specific actions:
Supination / Pronation: turning the palm upward or downward.
Inversion / Eversion: sole of the foot inward or outward.
Elevation / Depression: raising or lowering a body part (shoulder, jaw).
?????? Physiological Functions of Joints
1
️
⃣ Mobility: enables smooth body movements.
2
️
⃣ Support: maintains upright posture and stability.
3
️
⃣ Locomotion: allows walking, running, and body motion.
4
️
⃣ Shock Absorption: synovial fluid and cartilage cushion impacts.
5
️
⃣ Protection: provides flexibility, reducing risk of bone fracture.
in your regular teaching-and-exam pattern ??????
?????? Introduction
1. The physiology of joints explains how joints move and how they work together with bones, muscles,
ligaments, and synovial fluid.
2. Movements occur when muscles contract, pulling on bones that act as levers.
3. The synovial fluid and articular cartilage make the movement smooth and friction-free.
?????? Types of Movements at Synovial Joints
1
️
⃣ Gliding Movements
Flat bone surfaces slide over each other.
No angular change.
Example: between carpal bones of the wrist, or tarsal bones of the foot.
2
️
⃣ Angular Movements
Change the angle between two bones.
Flexion: bending, decreases the angle (elbow, knee).
Extension: straightening, increases the angle.
Abduction: movement away from the body’s midline (lifting arm sideways).
Adduction: movement toward the midline.
Circumduction: circular movement combining flexion, extension, abduction, and adduction (arm or leg
circles).
3
️
⃣ Rotational Movements
The bone turns around its own axis.
Medial rotation: toward the body’s midline.
Lateral rotation: away from the midline.
Example: rotation at the shoulder or hip joint.
4
️
⃣ Special Movements
Some joints show specific actions:
Supination / Pronation: turning the palm upward or downward.
Inversion / Eversion: sole of the foot inward or outward.
Elevation / Depression: raising or lowering a body part (shoulder, jaw).
?????? Physiological Functions of Joints
1
️
⃣ Mobility: enables smooth body movements.
2
️
⃣ Support: maintains upright posture and stability.
3
️
⃣ Locomotion: allows walking, running, and body motion.
4
️
⃣ Shock Absorption: synovial fluid and cartilage cushion impacts.
5
️
⃣ Protection: provides flexibility, reducing risk of bone fracture.
?????? Flow Chart – Movements and Functions of Joints
Muscle Contraction
↓
Movement at Joint
↓
Types of Movements
→ Gliding
→ Angular (Flexion, Extension, Abduction, Adduction, Circumduction)
→ Rotational (Medial / Lateral)
→ Special (Supination, Inversion, Elevation, etc.)
↓
Functions
→ Mobility
→ Support
→ Locomotion
→ Shock Absorption
→ Protection
?????? Conclusion
1. Joints act as mechanical levers for body movement.
2. Muscles, ligaments, cartilage, and synovial fluid maintain smooth and coordinated motion.
3. Healthy joint function ensures stability, protection, and flexibility of the skeletal system.
Muscle Contraction
↓
Movement at Joint
↓
Types of Movements
→ Gliding
→ Angular (Flexion, Extension, Abduction, Adduction, Circumduction)
→ Rotational (Medial / Lateral)
→ Special (Supination, Inversion, Elevation, etc.)
↓
Functions
→ Mobility
→ Support
→ Locomotion
→ Shock Absorption
→ Protection
?????? Conclusion
1. Joints act as mechanical levers for body movement.
2. Muscles, ligaments, cartilage, and synovial fluid maintain smooth and coordinated motion.
3. Healthy joint function ensures stability, protection, and flexibility of the skeletal system.
?????? PHYSIOLOGY OF BONE – OSSIFICATION (PROCESS OF BONE FORMATION)
?????? Definition
1. Ossification (or osteogenesis) is the process by which new bone is formed in the body.
2. It begins during embryonic life and continues until growth is complete.
3. Bone formation replaces either cartilage or membranous tissue depending on the type of ossification.
?????? Types of Ossification
1
️
⃣ Intramembranous Ossification
Occurs directly in membranous connective tissue.
Seen in flat bones such as skull, clavicle, and mandible.
Steps:
1. Mesenchymal cells cluster and differentiate into osteoblasts.
2. Osteoblasts secrete bone matrix (osteoid).
3. Calcium salts are deposited → calcification occurs.
4. Osteoblasts become osteocytes trapped in lacunae.
5. Trabeculae (spongy bone) form first, later converted to compact bone.
2
️
⃣ Endochondral Ossification
Occurs in pre-existing cartilage models.
Responsible for formation of long bones (femur, humerus, tibia).
Steps:
1. Development of cartilage model – mesenchymal cells → chondroblasts → cartilage framework.
2. Growth of cartilage model – cartilage enlarges, matrix calcifies.
3. Primary ossification center forms in the diaphysis.
4. Blood vessels invade → osteoblasts deposit bone matrix.
5. Secondary ossification centers appear in epiphyses.
6. Epiphyseal plate (growth plate) remains between diaphysis and epiphysis for lengthwise growth.
7. When growth stops, the epiphyseal plate is replaced by bone.
?????? Cells Involved in Ossification
Cell Type Function
Osteoblasts Bone-forming cells that secrete osteoid.
Osteocytes Mature bone cells that maintain bone matrix.
Osteoclasts Bone-resorbing cells for remodeling and calcium balance.
?????? Definition
1. Ossification (or osteogenesis) is the process by which new bone is formed in the body.
2. It begins during embryonic life and continues until growth is complete.
3. Bone formation replaces either cartilage or membranous tissue depending on the type of ossification.
?????? Types of Ossification
1
️
⃣ Intramembranous Ossification
Occurs directly in membranous connective tissue.
Seen in flat bones such as skull, clavicle, and mandible.
Steps:
1. Mesenchymal cells cluster and differentiate into osteoblasts.
2. Osteoblasts secrete bone matrix (osteoid).
3. Calcium salts are deposited → calcification occurs.
4. Osteoblasts become osteocytes trapped in lacunae.
5. Trabeculae (spongy bone) form first, later converted to compact bone.
2
️
⃣ Endochondral Ossification
Occurs in pre-existing cartilage models.
Responsible for formation of long bones (femur, humerus, tibia).
Steps:
1. Development of cartilage model – mesenchymal cells → chondroblasts → cartilage framework.
2. Growth of cartilage model – cartilage enlarges, matrix calcifies.
3. Primary ossification center forms in the diaphysis.
4. Blood vessels invade → osteoblasts deposit bone matrix.
5. Secondary ossification centers appear in epiphyses.
6. Epiphyseal plate (growth plate) remains between diaphysis and epiphysis for lengthwise growth.
7. When growth stops, the epiphyseal plate is replaced by bone.
?????? Cells Involved in Ossification
Cell Type Function
Osteoblasts Bone-forming cells that secrete osteoid.
Osteocytes Mature bone cells that maintain bone matrix.
Osteoclasts Bone-resorbing cells for remodeling and calcium balance.
?????? Factors Affecting Bone Formation
1. Nutrients: Calcium, phosphorus, vitamin D are essential.
2. Hormones: Growth hormone, thyroid hormone, parathyroid hormone, calcitonin, and sex hormones
regulate bone metabolism.
3. Physical activity: Weight-bearing exercise stimulates bone growth.
4. Blood supply: Adequate oxygen and nutrition support osteoblast function.
?????? Functions of Ossification
1. Provides support and shape to the body.
2. Enables protection of vital organs.
3. Allows attachment of muscles for movement.
4. Acts as a storehouse for calcium and phosphorus.
5. Helps in repair of fractures by new bone formation.
?????? Flow Chart – Process of Bone Ossification
Mesenchymal Cells
↓
Differentiate into Osteoblasts
↓
Secretion of Bone Matrix (Osteoid)
↓
Calcification → Formation of Trabeculae
↓
Development of Compact and Spongy Bone
↓
Maturation → Osteocytes in Lacunae
?????? Conclusion
1. Ossification is a continuous physiological process throughout life.
2. It ensures growth, remodeling, and repair of bones.
3. Proper nutrition, hormonal balance, and activity are vital for healthy skeletal development.
1. Nutrients: Calcium, phosphorus, vitamin D are essential.
2. Hormones: Growth hormone, thyroid hormone, parathyroid hormone, calcitonin, and sex hormones
regulate bone metabolism.
3. Physical activity: Weight-bearing exercise stimulates bone growth.
4. Blood supply: Adequate oxygen and nutrition support osteoblast function.
?????? Functions of Ossification
1. Provides support and shape to the body.
2. Enables protection of vital organs.
3. Allows attachment of muscles for movement.
4. Acts as a storehouse for calcium and phosphorus.
5. Helps in repair of fractures by new bone formation.
?????? Flow Chart – Process of Bone Ossification
Mesenchymal Cells
↓
Differentiate into Osteoblasts
↓
Secretion of Bone Matrix (Osteoid)
↓
Calcification → Formation of Trabeculae
↓
Development of Compact and Spongy Bone
↓
Maturation → Osteocytes in Lacunae
?????? Conclusion
1. Ossification is a continuous physiological process throughout life.
2. It ensures growth, remodeling, and repair of bones.
3. Proper nutrition, hormonal balance, and activity are vital for healthy skeletal development.
Physiology Topic: ?????? REGULATION OF BLOOD PRESSURE
?????? Introduction
Blood pressure is the force exerted by the circulating blood on the walls of the arteries.
It is an essential pressure that helps blood flow to all parts of the body.
Normal blood pressure in adults is about 120/80 mmHg (systolic/diastolic).
Regulation of blood pressure means maintaining this pressure within a normal range under rest, exercise,
stress, or sleep conditions.
?????? Definition
Regulation of blood pressure is the process by which the body maintains a steady and adequate arterial
pressure to ensure continuous blood flow to vital organs.
?????? Types of Regulation
1
️
⃣ Short-Term Regulation (Neural Control)
Acts within seconds or minutes.
Controlled by the nervous system (baroreceptors and chemoreceptors).
2
️
⃣ Long-Term Regulation (Hormonal and Renal Control)
Acts slowly, over hours or days.
Controlled by hormones and kidneys to maintain blood volume and vessel tone.
?????? Short-Term Regulation
A. Baroreceptor Reflex
1. Baroreceptors are stretch-sensitive receptors present in the carotid sinus and aortic arch.
2. When blood pressure increases, the baroreceptors are stretched.
3. They send signals to the medullary cardiovascular center in the brain.
4. The center increases parasympathetic activity and decreases sympathetic activity.
5. This causes vasodilation and slower heart rate, which brings down blood pressure.
✅ When blood pressure decreases, the opposite occurs:
Baroreceptors send fewer impulses.
The medulla increases sympathetic activity and decreases parasympathetic activity.
Heart rate and vasoconstriction increase → blood pressure rises back to normal.
B. Chemoreceptor Reflex
1. Chemoreceptors are located in the carotid and aortic bodies.
2. They detect changes such as low oxygen (O ), high carbon dioxide (CO ), or low pH in the blood.
₂ ₂
3. They stimulate the vasomotor center in the medulla.
4. This increases sympathetic discharge, leading to vasoconstriction and rise in BP.
?????? Long-Term Regulation
?????? Introduction
Blood pressure is the force exerted by the circulating blood on the walls of the arteries.
It is an essential pressure that helps blood flow to all parts of the body.
Normal blood pressure in adults is about 120/80 mmHg (systolic/diastolic).
Regulation of blood pressure means maintaining this pressure within a normal range under rest, exercise,
stress, or sleep conditions.
?????? Definition
Regulation of blood pressure is the process by which the body maintains a steady and adequate arterial
pressure to ensure continuous blood flow to vital organs.
?????? Types of Regulation
1
️
⃣ Short-Term Regulation (Neural Control)
Acts within seconds or minutes.
Controlled by the nervous system (baroreceptors and chemoreceptors).
2
️
⃣ Long-Term Regulation (Hormonal and Renal Control)
Acts slowly, over hours or days.
Controlled by hormones and kidneys to maintain blood volume and vessel tone.
?????? Short-Term Regulation
A. Baroreceptor Reflex
1. Baroreceptors are stretch-sensitive receptors present in the carotid sinus and aortic arch.
2. When blood pressure increases, the baroreceptors are stretched.
3. They send signals to the medullary cardiovascular center in the brain.
4. The center increases parasympathetic activity and decreases sympathetic activity.
5. This causes vasodilation and slower heart rate, which brings down blood pressure.
✅ When blood pressure decreases, the opposite occurs:
Baroreceptors send fewer impulses.
The medulla increases sympathetic activity and decreases parasympathetic activity.
Heart rate and vasoconstriction increase → blood pressure rises back to normal.
B. Chemoreceptor Reflex
1. Chemoreceptors are located in the carotid and aortic bodies.
2. They detect changes such as low oxygen (O ), high carbon dioxide (CO ), or low pH in the blood.
₂ ₂
3. They stimulate the vasomotor center in the medulla.
4. This increases sympathetic discharge, leading to vasoconstriction and rise in BP.
?????? Long-Term Regulation
A. Renin–Angiotensin–Aldosterone System (RAAS)
1. When BP or blood volume falls, kidneys release renin.
2. Renin converts angiotensinogen (from liver) into angiotensin I.
3. In the lungs, angiotensin-converting enzyme (ACE) changes it to angiotensin II.
4. Angiotensin II causes vasoconstriction and stimulates aldosterone secretion from adrenal cortex.
5. Aldosterone increases sodium and water reabsorption in kidneys.
6. This increases blood volume and BP returns to normal.
B. Antidiuretic Hormone (ADH / Vasopressin)
1. Secreted from the posterior pituitary gland when BP or blood volume falls.
2. Promotes water reabsorption in kidneys and causes vasoconstriction.
3. This increases blood volume and pressure.
C. Atrial Natriuretic Peptide (ANP)
1. Secreted from the atria of the heart when BP rises.
2. Promotes excretion of sodium and water from kidneys.
3. Causes vasodilation and decreases BP.
?????? Local (Autoregulation) Mechanism
1. Individual organs and tissues can regulate their own blood flow.
2. Vasodilator substances: Nitric oxide, adenosine, prostacyclin.
3. Vasoconstrictor substances: Endothelin, thromboxane, angiotensin II.
4. These local factors help maintain a constant blood supply even when systemic BP fluctuates.
?????? Clinical Importance
Hypertension: Persistent high blood pressure (>140/90 mmHg).
Hypotension: Abnormally low blood pressure (<90/60 mmHg).
Prolonged abnormal BP may damage heart, kidneys, brain, and blood vessels.
?????? Summary of Mechanism
When BP Decreases:
Baroreceptors less active → sympathetic nerves stimulated → heart rate and vasoconstriction increase.
Kidneys release renin → angiotensin II and aldosterone → vasoconstriction and water retention.
ADH released → water reabsorption → BP rises.
When BP Increases:
Baroreceptors more active → parasympathetic activity increases → heart rate slows and vessels dilate.
ANP released → sodium and water excretion → BP falls.
?????? Important Formula
Mean Arterial Pressure (MAP) = Cardiac Output × Total Peripheral Resistance
Where
1. When BP or blood volume falls, kidneys release renin.
2. Renin converts angiotensinogen (from liver) into angiotensin I.
3. In the lungs, angiotensin-converting enzyme (ACE) changes it to angiotensin II.
4. Angiotensin II causes vasoconstriction and stimulates aldosterone secretion from adrenal cortex.
5. Aldosterone increases sodium and water reabsorption in kidneys.
6. This increases blood volume and BP returns to normal.
B. Antidiuretic Hormone (ADH / Vasopressin)
1. Secreted from the posterior pituitary gland when BP or blood volume falls.
2. Promotes water reabsorption in kidneys and causes vasoconstriction.
3. This increases blood volume and pressure.
C. Atrial Natriuretic Peptide (ANP)
1. Secreted from the atria of the heart when BP rises.
2. Promotes excretion of sodium and water from kidneys.
3. Causes vasodilation and decreases BP.
?????? Local (Autoregulation) Mechanism
1. Individual organs and tissues can regulate their own blood flow.
2. Vasodilator substances: Nitric oxide, adenosine, prostacyclin.
3. Vasoconstrictor substances: Endothelin, thromboxane, angiotensin II.
4. These local factors help maintain a constant blood supply even when systemic BP fluctuates.
?????? Clinical Importance
Hypertension: Persistent high blood pressure (>140/90 mmHg).
Hypotension: Abnormally low blood pressure (<90/60 mmHg).
Prolonged abnormal BP may damage heart, kidneys, brain, and blood vessels.
?????? Summary of Mechanism
When BP Decreases:
Baroreceptors less active → sympathetic nerves stimulated → heart rate and vasoconstriction increase.
Kidneys release renin → angiotensin II and aldosterone → vasoconstriction and water retention.
ADH released → water reabsorption → BP rises.
When BP Increases:
Baroreceptors more active → parasympathetic activity increases → heart rate slows and vessels dilate.
ANP released → sodium and water excretion → BP falls.
?????? Important Formula
Mean Arterial Pressure (MAP) = Cardiac Output × Total Peripheral Resistance
Where
Cardiac Output (CO) = Heart Rate × Stroke Volume
TPR = Resistance in small arteries and arterioles.
?????? Flow Chart: Regulation of Blood Pressure
↓ BLOOD PRESSURE
↓
Baroreceptors less active
↓
↑ Sympathetic activity → Vasoconstriction + ↑ Heart Rate → ↑ BP
↓
Kidneys release Renin → Angiotensin II + Aldosterone → ↑ Water Retention → ↑ BP
↓
ADH secretion → ↑ Water Reabsorption → ↑ BP
↑ BLOOD PRESSURE
↓
Baroreceptors more active
↓
↑ Parasympathetic activity → ↓ Heart Rate + Vasodilation → ↓ BP
↓
ANP secretion → ↑ Water & Sodium Excretion → ↓ BP
TPR = Resistance in small arteries and arterioles.
?????? Flow Chart: Regulation of Blood Pressure
↓ BLOOD PRESSURE
↓
Baroreceptors less active
↓
↑ Sympathetic activity → Vasoconstriction + ↑ Heart Rate → ↑ BP
↓
Kidneys release Renin → Angiotensin II + Aldosterone → ↑ Water Retention → ↑ BP
↓
ADH secretion → ↑ Water Reabsorption → ↑ BP
↑ BLOOD PRESSURE
↓
Baroreceptors more active
↓
↑ Parasympathetic activity → ↓ Heart Rate + Vasodilation → ↓ BP
↓
ANP secretion → ↑ Water & Sodium Excretion → ↓ BP
?????? PHYSIOLOGY OF TISSUE FORMATION AND REPAIR
1
️
⃣ Diagram
✏️ Draw and label neatly:
Sequence of Injury → Inflammation → Granulation Tissue → Scar Formation (Healing)
Show new capillary formation, fibroblast activity, and epithelial regeneration.
2
️
⃣ Introduction
Whenever the body experiences injury or cell damage, it has a natural ability to heal and restore the tissue.
This process is called tissue repair, which ensures the structure and function of the tissue are regained.
It is a vital physiological mechanism that protects the body and prevents infection or fluid loss.
3
️
⃣ Definition
Tissue formation and repair is the physiological process by which damaged tissues are replaced or restored either
by the same type of cells (regeneration) or by connective tissue (fibrosis or scar formation).
4
️
⃣ Types of Tissue Repair
1. Regeneration:
Replacement of damaged cells by the same type of cells.
Occurs in tissues with high cell division, e.g., skin, liver, and mucous membranes.
2. Fibrosis (Scar Formation):
Replacement of damaged tissue by connective tissue.
Occurs when regeneration is not possible (e.g., in heart muscle and nervous tissue).
5
️
⃣ Physiological Stages of Tissue Repair
?????? 1. Hemostasis (Immediate Response)
After injury, blood vessels constrict to reduce blood loss.
Platelets form a temporary clot and release growth factors.
This step seals the wound and prepares the site for repair.
?????? 2. Inflammatory Phase
White blood cells (neutrophils and macrophages) move to the injury site.
They remove dead cells, bacteria, and debris.
Redness, heat, and swelling occur as part of the body’s defense.
?????? 3. Proliferative Phase (Tissue Formation)
Fibroblasts form collagen fibers and produce granulation tissue.
New capillaries grow into the damaged area (angiogenesis).
Epithelial cells spread to cover the wound.
?????? 4. Remodeling or Maturation Phase
Collagen fibers reorganize, increasing tissue strength.
The wound contracts, and scar tissue forms.
1
️
⃣ Diagram
✏️ Draw and label neatly:
Sequence of Injury → Inflammation → Granulation Tissue → Scar Formation (Healing)
Show new capillary formation, fibroblast activity, and epithelial regeneration.
2
️
⃣ Introduction
Whenever the body experiences injury or cell damage, it has a natural ability to heal and restore the tissue.
This process is called tissue repair, which ensures the structure and function of the tissue are regained.
It is a vital physiological mechanism that protects the body and prevents infection or fluid loss.
3
️
⃣ Definition
Tissue formation and repair is the physiological process by which damaged tissues are replaced or restored either
by the same type of cells (regeneration) or by connective tissue (fibrosis or scar formation).
4
️
⃣ Types of Tissue Repair
1. Regeneration:
Replacement of damaged cells by the same type of cells.
Occurs in tissues with high cell division, e.g., skin, liver, and mucous membranes.
2. Fibrosis (Scar Formation):
Replacement of damaged tissue by connective tissue.
Occurs when regeneration is not possible (e.g., in heart muscle and nervous tissue).
5
️
⃣ Physiological Stages of Tissue Repair
?????? 1. Hemostasis (Immediate Response)
After injury, blood vessels constrict to reduce blood loss.
Platelets form a temporary clot and release growth factors.
This step seals the wound and prepares the site for repair.
?????? 2. Inflammatory Phase
White blood cells (neutrophils and macrophages) move to the injury site.
They remove dead cells, bacteria, and debris.
Redness, heat, and swelling occur as part of the body’s defense.
?????? 3. Proliferative Phase (Tissue Formation)
Fibroblasts form collagen fibers and produce granulation tissue.
New capillaries grow into the damaged area (angiogenesis).
Epithelial cells spread to cover the wound.
?????? 4. Remodeling or Maturation Phase
Collagen fibers reorganize, increasing tissue strength.
The wound contracts, and scar tissue forms.
The tissue regains its shape and partial function.
6
️
⃣ Factors Influencing Tissue Repair
1. Age: Slower healing in older people.
2. Nutrition: Protein, Vitamin C, and Zinc help in collagen formation.
3. Blood Supply: Adequate oxygen improves healing.
4. Infection: Delays the healing process.
5. Hormones: Cortisol and stress hormones slow tissue repair.
7
️
⃣ Flow Chart – Stages of Tissue Repair
TISSUE INJURY
↓
HEMOSTASIS → Clot Formation
↓
INFLAMMATION → WBCs Clean the Area
↓
PROLIFERATION → Fibroblast + Collagen + Capillaries
↓
MATURATION → Collagen Remodeling + Scar Formation
↓
HEALED TISSUE (Structure & Function Restored)
8
️
⃣ Conclusion
Tissue repair is an automatic physiological mechanism that restores damaged tissues.
It occurs through inflammation, tissue formation, and remodeling.
Proper nutrition, blood supply, and cleanliness help complete healing with minimal scarring.
6
️
⃣ Factors Influencing Tissue Repair
1. Age: Slower healing in older people.
2. Nutrition: Protein, Vitamin C, and Zinc help in collagen formation.
3. Blood Supply: Adequate oxygen improves healing.
4. Infection: Delays the healing process.
5. Hormones: Cortisol and stress hormones slow tissue repair.
7
️
⃣ Flow Chart – Stages of Tissue Repair
TISSUE INJURY
↓
HEMOSTASIS → Clot Formation
↓
INFLAMMATION → WBCs Clean the Area
↓
PROLIFERATION → Fibroblast + Collagen + Capillaries
↓
MATURATION → Collagen Remodeling + Scar Formation
↓
HEALED TISSUE (Structure & Function Restored)
8
️
⃣ Conclusion
Tissue repair is an automatic physiological mechanism that restores damaged tissues.
It occurs through inflammation, tissue formation, and remodeling.
Proper nutrition, blood supply, and cleanliness help complete healing with minimal scarring.
?????? FUNCTIONS OF ...
(Pineal Gland – Hypothalamus – Thymus Gland + General Functions of Hormones)
1
️
⃣ Pineal Gland
?????? Location: Between the two cerebral hemispheres, deep inside the brain.
Functions:
1. Secretes melatonin hormone.
2. Controls the sleep and wake cycle.
3. Maintains the body’s biological clock (day–night rhythm).
4. Helps in sexual development and reproductive timing.
5. Acts as an antioxidant, protecting brain cells.
2
️
⃣ Hypothalamus
?????? Location: Below the thalamus in the brain.
Functions:
1. Connects the nervous system and endocrine system.
2. Produces many releasing and inhibiting hormones which control the pituitary gland.
3. Regulates body temperature, hunger, thirst, and emotions.
4. Maintains homeostasis (balance inside the body).
5. Important hormones and their short functions:
TRH – Stimulates thyroid hormone release.
CRH – Controls adrenal gland function.
GnRH – Regulates reproductive hormones (FSH and LH).
GHRH – Stimulates growth hormone.
Somatostatin – Stops growth hormone when needed.
3
️
⃣ Thymus Gland
?????? Location: In the upper chest, behind the sternum (breastbone).
Functions:
1. Produces Thymosin hormone.
2. Helps in the formation of T-lymphocytes (T-cells).
3. Builds immunity and helps the body fight infections.
4. Most active in children and becomes smaller after puberty.
4
️
⃣ General Functions of Hormones
1. Control growth and development — Growth Hormone (GH).
2. Regulate metabolism and energy use — Thyroxine, Insulin.
3. Maintain water and salt balance — ADH, Aldosterone.
4. Control blood pressure and heart activity — Adrenaline.
(Pineal Gland – Hypothalamus – Thymus Gland + General Functions of Hormones)
1
️
⃣ Pineal Gland
?????? Location: Between the two cerebral hemispheres, deep inside the brain.
Functions:
1. Secretes melatonin hormone.
2. Controls the sleep and wake cycle.
3. Maintains the body’s biological clock (day–night rhythm).
4. Helps in sexual development and reproductive timing.
5. Acts as an antioxidant, protecting brain cells.
2
️
⃣ Hypothalamus
?????? Location: Below the thalamus in the brain.
Functions:
1. Connects the nervous system and endocrine system.
2. Produces many releasing and inhibiting hormones which control the pituitary gland.
3. Regulates body temperature, hunger, thirst, and emotions.
4. Maintains homeostasis (balance inside the body).
5. Important hormones and their short functions:
TRH – Stimulates thyroid hormone release.
CRH – Controls adrenal gland function.
GnRH – Regulates reproductive hormones (FSH and LH).
GHRH – Stimulates growth hormone.
Somatostatin – Stops growth hormone when needed.
3
️
⃣ Thymus Gland
?????? Location: In the upper chest, behind the sternum (breastbone).
Functions:
1. Produces Thymosin hormone.
2. Helps in the formation of T-lymphocytes (T-cells).
3. Builds immunity and helps the body fight infections.
4. Most active in children and becomes smaller after puberty.
4
️
⃣ General Functions of Hormones
1. Control growth and development — Growth Hormone (GH).
2. Regulate metabolism and energy use — Thyroxine, Insulin.
3. Maintain water and salt balance — ADH, Aldosterone.
4. Control blood pressure and heart activity — Adrenaline.
5. Regulate reproductive functions — Estrogen, Progesterone, Testosterone.
6. Help maintain body balance (homeostasis) — Cortisol, Insulin, ADH.
?????? Conclusion
Pineal gland, hypothalamus, and thymus gland are small but vital endocrine glands.
They work together with other glands to control sleep, body balance, growth, and immunity through hormones.
6. Help maintain body balance (homeostasis) — Cortisol, Insulin, ADH.
?????? Conclusion
Pineal gland, hypothalamus, and thymus gland are small but vital endocrine glands.
They work together with other glands to control sleep, body balance, growth, and immunity through hormones.
?????? FUNCTIONS OF the following glands
1
️
⃣ Diagram
Students should draw and label a clear diagram showing all major endocrine glands — Pituitary, Thyroid,
Parathyroid, Adrenal, Pancreas, Ovaries, and Testes.
2
️
⃣ Definition
The endocrine glands are ductless glands that secrete hormones directly into the bloodstream.
These hormones act as chemical messengers that help control and coordinate body activities such as growth,
metabolism, reproduction, and stress response.
3
️
⃣ Main Endocrine Glands and Their Functions
A. Pituitary Gland – “Master Gland”
1. Located at the base of the brain.
2. Controls the function of other endocrine glands.
3. Growth Hormone (GH): Promotes growth and repair of tissues.
4. Thyroid-Stimulating Hormone (TSH): Stimulates thyroid hormone secretion.
5. Adrenocorticotropic Hormone (ACTH): Stimulates the adrenal cortex.
6. Follicle-Stimulating Hormone (FSH): Helps in egg and sperm production.
7. Luteinizing Hormone (LH): Stimulates ovulation and secretion of testosterone.
8. Prolactin: Stimulates milk secretion after childbirth.
9. Antidiuretic Hormone (ADH): Controls water balance in the body.
10. Oxytocin: Causes uterine contraction during childbirth and milk ejection during feeding.
B. Thyroid Gland
1. Located in the neck, below the larynx.
2. Thyroxine (T ) and Triiodothyronine (T ) control metabolism, oxygen use, and body energy.
₄ ₃
3. Calcitonin helps lower blood calcium by depositing calcium in bones.
C. Parathyroid Glands
1. Four small glands situated behind the thyroid gland.
2. Parathormone (PTH): Increases blood calcium and decreases phosphate level.
3. Helps maintain normal excitability of muscles and nerves.
D. Adrenal Glands
1. Located above each kidney.
2. Each gland has two parts — Cortex and Medulla.
3. Adrenal Cortex:
Aldosterone: Maintains sodium and water balance.
Cortisol: Helps in metabolism and stress control.
Androgens: Contribute to sexual characteristics.
4. Adrenal Medulla:
1
️
⃣ Diagram
Students should draw and label a clear diagram showing all major endocrine glands — Pituitary, Thyroid,
Parathyroid, Adrenal, Pancreas, Ovaries, and Testes.
2
️
⃣ Definition
The endocrine glands are ductless glands that secrete hormones directly into the bloodstream.
These hormones act as chemical messengers that help control and coordinate body activities such as growth,
metabolism, reproduction, and stress response.
3
️
⃣ Main Endocrine Glands and Their Functions
A. Pituitary Gland – “Master Gland”
1. Located at the base of the brain.
2. Controls the function of other endocrine glands.
3. Growth Hormone (GH): Promotes growth and repair of tissues.
4. Thyroid-Stimulating Hormone (TSH): Stimulates thyroid hormone secretion.
5. Adrenocorticotropic Hormone (ACTH): Stimulates the adrenal cortex.
6. Follicle-Stimulating Hormone (FSH): Helps in egg and sperm production.
7. Luteinizing Hormone (LH): Stimulates ovulation and secretion of testosterone.
8. Prolactin: Stimulates milk secretion after childbirth.
9. Antidiuretic Hormone (ADH): Controls water balance in the body.
10. Oxytocin: Causes uterine contraction during childbirth and milk ejection during feeding.
B. Thyroid Gland
1. Located in the neck, below the larynx.
2. Thyroxine (T ) and Triiodothyronine (T ) control metabolism, oxygen use, and body energy.
₄ ₃
3. Calcitonin helps lower blood calcium by depositing calcium in bones.
C. Parathyroid Glands
1. Four small glands situated behind the thyroid gland.
2. Parathormone (PTH): Increases blood calcium and decreases phosphate level.
3. Helps maintain normal excitability of muscles and nerves.
D. Adrenal Glands
1. Located above each kidney.
2. Each gland has two parts — Cortex and Medulla.
3. Adrenal Cortex:
Aldosterone: Maintains sodium and water balance.
Cortisol: Helps in metabolism and stress control.
Androgens: Contribute to sexual characteristics.
4. Adrenal Medulla:
Adrenaline: Increases heart rate and energy during emergency (“fight or flight”).
Noradrenaline: Maintains blood pressure.
E. Pancreas
1. Located behind the stomach.
2. Acts as both an endocrine and exocrine gland.
3. Insulin: Lowers blood glucose level.
4. Glucagon: Raises blood glucose level.
5. Somatostatin: Regulates both insulin and glucagon secretion.
6. Maintains constant blood sugar level in the body.
F. Gonads (Reproductive Glands)
1. Ovaries (in females):
Estrogen: Develops female secondary sexual characters.
Progesterone: Maintains pregnancy and regulates menstrual cycle.
2. Testes (in males):
Testosterone: Develops male secondary sexual characters and supports sperm production.
4
️
⃣ Summary
1. The endocrine glands secrete hormones directly into the bloodstream.
2. These hormones regulate vital body functions like growth, energy balance, reproduction, and metabolism.
3. The pituitary gland acts as the master gland controlling other glands.
4. Any imbalance in hormone secretion can lead to disorders such as diabetes, goitre, or hormonal deficiency.
5
️
⃣ Conclusion
The endocrine system maintains homeostasis by coordinating the activities of all body systems.
Its hormones act slowly but have long-lasting effects essential for normal body function and health.
Noradrenaline: Maintains blood pressure.
E. Pancreas
1. Located behind the stomach.
2. Acts as both an endocrine and exocrine gland.
3. Insulin: Lowers blood glucose level.
4. Glucagon: Raises blood glucose level.
5. Somatostatin: Regulates both insulin and glucagon secretion.
6. Maintains constant blood sugar level in the body.
F. Gonads (Reproductive Glands)
1. Ovaries (in females):
Estrogen: Develops female secondary sexual characters.
Progesterone: Maintains pregnancy and regulates menstrual cycle.
2. Testes (in males):
Testosterone: Develops male secondary sexual characters and supports sperm production.
4
️
⃣ Summary
1. The endocrine glands secrete hormones directly into the bloodstream.
2. These hormones regulate vital body functions like growth, energy balance, reproduction, and metabolism.
3. The pituitary gland acts as the master gland controlling other glands.
4. Any imbalance in hormone secretion can lead to disorders such as diabetes, goitre, or hormonal deficiency.
5
️
⃣ Conclusion
The endocrine system maintains homeostasis by coordinating the activities of all body systems.
Its hormones act slowly but have long-lasting effects essential for normal body function and health.
Functions of the following organs
(Cerebral Cortex, Cerebellum, Brainstem – Medulla and Pons)
1
️
⃣ Cerebral Cortex
1. The cerebral cortex is the outer layer of the brain that controls all higher mental activities.
2. It helps us to think, learn, remember, and make decisions.
3. It receives sensory information such as touch, pain, sight, hearing, and taste.
4. It helps in speaking, writing, and understanding language.
5. It controls all voluntary movements of the body.
6. It also helps to control emotions, behavior, and personality.
7. The right side of the brain controls the left side of the body, and the left side controls the right side.
2
️
⃣ Cerebellum
1. The cerebellum lies below the cerebrum and is responsible for balance and coordination.
2. It helps to maintain body posture and muscle tone.
3. It makes all our body movements smooth, accurate, and well-coordinated.
4. It helps in learning new body movements such as writing or walking.
5. It also controls eye movement and balance while walking.
6. If the cerebellum is damaged, movements become jerky and unsteady.
3
️
⃣ Brainstem (Medulla and Pons)
1. The brainstem connects the brain with the spinal cord and controls basic life functions.
2. It has three main parts — midbrain, pons, and medulla oblongata.
Medulla Oblongata:
1. Controls heartbeat, breathing, and blood pressure.
2. Regulates vomiting, coughing, sneezing, and swallowing reflexes.
3. Helps in digestion movements and muscle control of internal organs.
Pons:
1. Connects the cerebrum and cerebellum for coordination.
2. Helps in facial expressions and eye movement.
3. Plays a role in sleep, dreaming, and awareness.
✅ Conclusion
The nervous system acts as the body’s control and communication network.
It receives information, processes it, and sends signals to control movement, emotions, and vital activities like
breathing and heartbeat — keeping the body balanced and functioning properly.
(Cerebral Cortex, Cerebellum, Brainstem – Medulla and Pons)
1
️
⃣ Cerebral Cortex
1. The cerebral cortex is the outer layer of the brain that controls all higher mental activities.
2. It helps us to think, learn, remember, and make decisions.
3. It receives sensory information such as touch, pain, sight, hearing, and taste.
4. It helps in speaking, writing, and understanding language.
5. It controls all voluntary movements of the body.
6. It also helps to control emotions, behavior, and personality.
7. The right side of the brain controls the left side of the body, and the left side controls the right side.
2
️
⃣ Cerebellum
1. The cerebellum lies below the cerebrum and is responsible for balance and coordination.
2. It helps to maintain body posture and muscle tone.
3. It makes all our body movements smooth, accurate, and well-coordinated.
4. It helps in learning new body movements such as writing or walking.
5. It also controls eye movement and balance while walking.
6. If the cerebellum is damaged, movements become jerky and unsteady.
3
️
⃣ Brainstem (Medulla and Pons)
1. The brainstem connects the brain with the spinal cord and controls basic life functions.
2. It has three main parts — midbrain, pons, and medulla oblongata.
Medulla Oblongata:
1. Controls heartbeat, breathing, and blood pressure.
2. Regulates vomiting, coughing, sneezing, and swallowing reflexes.
3. Helps in digestion movements and muscle control of internal organs.
Pons:
1. Connects the cerebrum and cerebellum for coordination.
2. Helps in facial expressions and eye movement.
3. Plays a role in sleep, dreaming, and awareness.
✅ Conclusion
The nervous system acts as the body’s control and communication network.
It receives information, processes it, and sends signals to control movement, emotions, and vital activities like
breathing and heartbeat — keeping the body balanced and functioning properly.
?????? PHYSIOLOGY OF ERYTHROPOIESIS
1
️
⃣ Diagram
Draw and label the stages of Red Blood Cell (RBC) formation in bone marrow:
Hemocytoblast (stem cell)
Proerythroblast
Basophilic erythroblast
Polychromatic erythroblast
Orthochromatic erythroblast (normoblast)
Reticulocyte
Mature Erythrocyte (RBC)
2
️
⃣ Definition
Erythropoiesis is the physiological process by which red blood cells (erythrocytes) are formed from stem cells in
the bone marrow.
It ensures a constant number of RBCs in circulation to carry oxygen throughout the body.
3
️
⃣ Site of Erythropoiesis
1. Embryonic stage: In the yolk sac.
2. Fetal stage: In the liver and spleen.
3. After birth (Adult): In red bone marrow — mainly in sternum, ribs, vertebrae, skull, and ends of long bones.
4
️
⃣ Stages of Erythropoiesis
1. Hemocytoblast (Stem Cell): The parent cell capable of forming all blood cells.
2. Proerythroblast: Large cell with a nucleus; first recognizable RBC precursor.
3. Basophilic Erythroblast: Synthesizes hemoglobin; cytoplasm stains blue.
4. Polychromatic Erythroblast: Cytoplasm becomes grayish as hemoglobin increases.
5. Orthochromatic Erythroblast (Normoblast): Nucleus becomes small and is expelled.
6. Reticulocyte: Immature RBC released into circulation; contains remnants of RNA.
7. Mature Erythrocyte: Biconcave, anucleate cell capable of carrying oxygen with hemoglobin.
5
️
⃣ Factors Influencing Erythropoiesis
1. Erythropoietin (EPO):
Hormone secreted by the kidneys (in response to low oxygen).
Stimulates bone marrow to produce more RBCs.
2. Nutrients:
Iron – needed for hemoglobin formation.
Vitamin B and Folic acid – for nuclear maturation.
₁₂
Protein and amino acids – for cell membrane and enzymes.
3. Hormones:
Androgens and Thyroxine accelerate RBC production.
1
️
⃣ Diagram
Draw and label the stages of Red Blood Cell (RBC) formation in bone marrow:
Hemocytoblast (stem cell)
Proerythroblast
Basophilic erythroblast
Polychromatic erythroblast
Orthochromatic erythroblast (normoblast)
Reticulocyte
Mature Erythrocyte (RBC)
2
️
⃣ Definition
Erythropoiesis is the physiological process by which red blood cells (erythrocytes) are formed from stem cells in
the bone marrow.
It ensures a constant number of RBCs in circulation to carry oxygen throughout the body.
3
️
⃣ Site of Erythropoiesis
1. Embryonic stage: In the yolk sac.
2. Fetal stage: In the liver and spleen.
3. After birth (Adult): In red bone marrow — mainly in sternum, ribs, vertebrae, skull, and ends of long bones.
4
️
⃣ Stages of Erythropoiesis
1. Hemocytoblast (Stem Cell): The parent cell capable of forming all blood cells.
2. Proerythroblast: Large cell with a nucleus; first recognizable RBC precursor.
3. Basophilic Erythroblast: Synthesizes hemoglobin; cytoplasm stains blue.
4. Polychromatic Erythroblast: Cytoplasm becomes grayish as hemoglobin increases.
5. Orthochromatic Erythroblast (Normoblast): Nucleus becomes small and is expelled.
6. Reticulocyte: Immature RBC released into circulation; contains remnants of RNA.
7. Mature Erythrocyte: Biconcave, anucleate cell capable of carrying oxygen with hemoglobin.
5
️
⃣ Factors Influencing Erythropoiesis
1. Erythropoietin (EPO):
Hormone secreted by the kidneys (in response to low oxygen).
Stimulates bone marrow to produce more RBCs.
2. Nutrients:
Iron – needed for hemoglobin formation.
Vitamin B and Folic acid – for nuclear maturation.
₁₂
Protein and amino acids – for cell membrane and enzymes.
3. Hormones:
Androgens and Thyroxine accelerate RBC production.
4. Healthy bone marrow – required for proper cell maturation.
5. Oxygen level:
Low oxygen (hypoxia) increases erythropoietin release and stimulates erythropoiesis.
6
️
⃣ Regulation of Erythropoiesis
A feedback mechanism controls RBC production:
↓ Oxygen (Hypoxia) → ↑ Erythropoietin secretion by kidneys →
↑ Bone marrow stimulation → ↑ RBC production →
↑ Oxygen level → Normal oxygen restores balance.
7
️
⃣ Functions of Erythropoiesis
1. Maintains normal RBC count (about 5 million/mm³).
2. Ensures adequate hemoglobin for oxygen transport.
3. Replaces old or destroyed RBCs continuously.
4. Maintains normal blood viscosity and pH balance.
8
️
⃣ Flow Chart – Process of Erythropoiesis
Hemocytoblast → Proerythroblast → Basophilic Erythroblast → Polychromatic Erythroblast → Orthochromatic
Erythroblast (Normoblast) → Reticulocyte → Mature Erythrocyte (RBC)
9
️
⃣ Conclusion
Erythropoiesis is a continuous, hormone-controlled process ensuring a steady supply of red blood cells.
It depends on erythropoietin, nutrients, hormones, and bone-marrow health, maintaining the body’s oxygen
transport and overall homeostasis.
5. Oxygen level:
Low oxygen (hypoxia) increases erythropoietin release and stimulates erythropoiesis.
6
️
⃣ Regulation of Erythropoiesis
A feedback mechanism controls RBC production:
↓ Oxygen (Hypoxia) → ↑ Erythropoietin secretion by kidneys →
↑ Bone marrow stimulation → ↑ RBC production →
↑ Oxygen level → Normal oxygen restores balance.
7
️
⃣ Functions of Erythropoiesis
1. Maintains normal RBC count (about 5 million/mm³).
2. Ensures adequate hemoglobin for oxygen transport.
3. Replaces old or destroyed RBCs continuously.
4. Maintains normal blood viscosity and pH balance.
8
️
⃣ Flow Chart – Process of Erythropoiesis
Hemocytoblast → Proerythroblast → Basophilic Erythroblast → Polychromatic Erythroblast → Orthochromatic
Erythroblast (Normoblast) → Reticulocyte → Mature Erythrocyte (RBC)
9
️
⃣ Conclusion
Erythropoiesis is a continuous, hormone-controlled process ensuring a steady supply of red blood cells.
It depends on erythropoietin, nutrients, hormones, and bone-marrow health, maintaining the body’s oxygen
transport and overall homeostasis.
⚙️ PHYSIOLOGY OF MUSCLE CONTRACTION
1
️
⃣ Introduction
Muscle contraction is a physiological process where muscle fibers shorten and produce force.
It happens when a nerve impulse stimulates the muscle, causing the proteins actin and myosin to slide over each
other.
This process helps in all body movements such as walking, breathing, and heart beating.
2
️
⃣ Excitation–Contraction Coupling
1. A nerve impulse reaches the neuromuscular junction.
2. The neurotransmitter acetylcholine (ACh) is released into the synaptic cleft.
3. ACh binds to receptors on the sarcolemma (muscle membrane), creating an action potential.
4. The action potential travels along the sarcolemma and through T-tubules.
5. This signal causes the sarcoplasmic reticulum to release calcium ions (Ca² ) into the sarcoplasm.
⁺
3
️
⃣ Sliding Filament Mechanism
1. The released Ca² ions bind to troponin on the actin filament.
⁺
2. This moves tropomyosin, exposing the binding sites on actin.
3. Myosin heads attach to the actin, forming cross-bridges.
4. With ATP energy, myosin heads pull the actin filaments inward, shortening the sarcomere.
5. When ATP binds again, myosin detaches and the cycle repeats.
6. As long as ATP and Ca² are available, contraction continues.
⁺
4
️
⃣ Relaxation of Muscle
1. When the nerve impulse stops, acetylcholinesterase breaks down ACh.
2. Calcium ions are pumped back into the sarcoplasmic reticulum.
3. The binding sites on actin are covered again.
4. Actin and myosin detach, and the muscle fiber returns to its resting length.
5
️
⃣ Role of ATP
ATP provides energy for three main functions:
1. Cross-bridge formation and movement.
2. Detachment of myosin from actin.
3. Pumping Ca² ions back into storage for muscle relaxation.
⁺
6
️
⃣ Flow Chart – Mechanism of Muscle Contraction
Nerve Impulse → ACh Release → Action Potential on Sarcolemma → Ca² Released → Actin–Myosin
⁺
Interaction → Cross-Bridge Formation → Sliding of Filaments → Muscle Shortening → Relaxation
?????? Conclusion
Muscle contraction is an energy-dependent process controlled by nerve signals, calcium ions, and ATP.
It enables both voluntary and involuntary movements essential for life functions.
1
️
⃣ Introduction
Muscle contraction is a physiological process where muscle fibers shorten and produce force.
It happens when a nerve impulse stimulates the muscle, causing the proteins actin and myosin to slide over each
other.
This process helps in all body movements such as walking, breathing, and heart beating.
2
️
⃣ Excitation–Contraction Coupling
1. A nerve impulse reaches the neuromuscular junction.
2. The neurotransmitter acetylcholine (ACh) is released into the synaptic cleft.
3. ACh binds to receptors on the sarcolemma (muscle membrane), creating an action potential.
4. The action potential travels along the sarcolemma and through T-tubules.
5. This signal causes the sarcoplasmic reticulum to release calcium ions (Ca² ) into the sarcoplasm.
⁺
3
️
⃣ Sliding Filament Mechanism
1. The released Ca² ions bind to troponin on the actin filament.
⁺
2. This moves tropomyosin, exposing the binding sites on actin.
3. Myosin heads attach to the actin, forming cross-bridges.
4. With ATP energy, myosin heads pull the actin filaments inward, shortening the sarcomere.
5. When ATP binds again, myosin detaches and the cycle repeats.
6. As long as ATP and Ca² are available, contraction continues.
⁺
4
️
⃣ Relaxation of Muscle
1. When the nerve impulse stops, acetylcholinesterase breaks down ACh.
2. Calcium ions are pumped back into the sarcoplasmic reticulum.
3. The binding sites on actin are covered again.
4. Actin and myosin detach, and the muscle fiber returns to its resting length.
5
️
⃣ Role of ATP
ATP provides energy for three main functions:
1. Cross-bridge formation and movement.
2. Detachment of myosin from actin.
3. Pumping Ca² ions back into storage for muscle relaxation.
⁺
6
️
⃣ Flow Chart – Mechanism of Muscle Contraction
Nerve Impulse → ACh Release → Action Potential on Sarcolemma → Ca² Released → Actin–Myosin
⁺
Interaction → Cross-Bridge Formation → Sliding of Filaments → Muscle Shortening → Relaxation
?????? Conclusion
Muscle contraction is an energy-dependent process controlled by nerve signals, calcium ions, and ATP.
It enables both voluntary and involuntary movements essential for life functions.
?????? PHYSIOLOGY OF THE CELL
1
️
⃣ Diagram
✏️ Draw and label neatly:
Cell membrane – Cytoplasm – Nucleus – Mitochondria – Ribosomes – Endoplasmic Reticulum (Smooth &
Rough) – Golgi Apparatus – Lysosomes
2
️
⃣ Introduction
The cell is the basic structural and functional unit of all living organisms.
Cell physiology explains how the cell works to perform essential functions like energy production, protein
synthesis, communication, growth, and repair.
Proper functioning of all cells ensures the survival of the body as a whole.
3
️
⃣ Definition
Cell Physiology is the study of how cells function, including the physical and chemical processes that occur within
them to sustain life.
4
️
⃣ Main Functions of the Cell
?????? 1. Transport of Substances
The cell membrane controls movement of materials.
Includes:
Diffusion → Movement from high to low concentration
Osmosis → Movement of water
Active Transport → Requires energy (ATP) to move materials against the gradient
?????? 2. Energy Production
Takes place in mitochondria, known as the powerhouse of the cell.
Energy is produced in the form of ATP (Adenosine Triphosphate) through cellular respiration.
?????? 3. Protein Synthesis
Ribosomes make proteins.
Rough Endoplasmic Reticulum (RER) helps in protein synthesis.
Golgi Apparatus modifies and packages proteins for transport.
?????? 4. Waste Removal
Lysosomes contain digestive enzymes that break down waste, damaged organelles, and foreign substances.
?????? 5. Communication
Cells communicate through chemical messengers (like hormones and neurotransmitters).
?????? 6. Growth and Division
Cells grow in size and divide through mitosis and meiosis for repair and reproduction.
1
️
⃣ Diagram
✏️ Draw and label neatly:
Cell membrane – Cytoplasm – Nucleus – Mitochondria – Ribosomes – Endoplasmic Reticulum (Smooth &
Rough) – Golgi Apparatus – Lysosomes
2
️
⃣ Introduction
The cell is the basic structural and functional unit of all living organisms.
Cell physiology explains how the cell works to perform essential functions like energy production, protein
synthesis, communication, growth, and repair.
Proper functioning of all cells ensures the survival of the body as a whole.
3
️
⃣ Definition
Cell Physiology is the study of how cells function, including the physical and chemical processes that occur within
them to sustain life.
4
️
⃣ Main Functions of the Cell
?????? 1. Transport of Substances
The cell membrane controls movement of materials.
Includes:
Diffusion → Movement from high to low concentration
Osmosis → Movement of water
Active Transport → Requires energy (ATP) to move materials against the gradient
?????? 2. Energy Production
Takes place in mitochondria, known as the powerhouse of the cell.
Energy is produced in the form of ATP (Adenosine Triphosphate) through cellular respiration.
?????? 3. Protein Synthesis
Ribosomes make proteins.
Rough Endoplasmic Reticulum (RER) helps in protein synthesis.
Golgi Apparatus modifies and packages proteins for transport.
?????? 4. Waste Removal
Lysosomes contain digestive enzymes that break down waste, damaged organelles, and foreign substances.
?????? 5. Communication
Cells communicate through chemical messengers (like hormones and neurotransmitters).
?????? 6. Growth and Division
Cells grow in size and divide through mitosis and meiosis for repair and reproduction.
?????? 7. Maintenance of Homeostasis
The cell maintains a stable internal environment by balancing pH, ions, and fluid levels.
5
️
⃣ Flow Chart – Overview of Cell Physiology
PHYSIOLOGY OF THE CELL
↓
MAIN CELL FUNCTIONS
↓
┌───────────────────────────────────┐
│ 1. Transport of Substances │
│ 2. Energy Production (Mitochondria)│
│ 3. Protein Synthesis (RER & Ribosome) │
│ 4. Waste Removal (Lysosomes) │
│ 5. Communication (Chemical Signals) │
│ 6. Growth & Division (Mitosis) │
│ 7. Homeostasis Maintenance │
└───────────────────────────────────┘
↓
RESULT → LIFE PROCESSES MAINTAINED
6
️
⃣ Conclusion
The cell performs several vital functions necessary for growth, repair, and energy production.
All organelles work together harmoniously to maintain life and balance (homeostasis).
Thus, the cell is the foundation of all physiological processes in the human body.
The cell maintains a stable internal environment by balancing pH, ions, and fluid levels.
5
️
⃣ Flow Chart – Overview of Cell Physiology
PHYSIOLOGY OF THE CELL
↓
MAIN CELL FUNCTIONS
↓
┌───────────────────────────────────┐
│ 1. Transport of Substances │
│ 2. Energy Production (Mitochondria)│
│ 3. Protein Synthesis (RER & Ribosome) │
│ 4. Waste Removal (Lysosomes) │
│ 5. Communication (Chemical Signals) │
│ 6. Growth & Division (Mitosis) │
│ 7. Homeostasis Maintenance │
└───────────────────────────────────┘
↓
RESULT → LIFE PROCESSES MAINTAINED
6
️
⃣ Conclusion
The cell performs several vital functions necessary for growth, repair, and energy production.
All organelles work together harmoniously to maintain life and balance (homeostasis).
Thus, the cell is the foundation of all physiological processes in the human body.
?????? PHYSIOLOGY OF HEMOSTASIS (PROCESS OF BLOOD CLOTTING)
?????? 1
️
⃣ Introduction
When a blood vessel is injured, bleeding starts immediately.
The body activates a natural process called hemostasis to stop bleeding and prevent blood loss.
It involves the blood vessels, platelets, and plasma clotting factors.
?????? 2
️
⃣ Definition
Hemostasis is the physiological process by which bleeding is stopped after injury.
It includes three stages:
1. Vascular spasm
2. Platelet plug formation
3. Blood coagulation
?????? 3
️
⃣ Stages of Hemostasis
Stage 1: Vascular Spasm (Vasoconstriction)
When a blood vessel is cut, the smooth muscles in its wall contract.
This narrows the vessel and reduces blood flow to the injured area.
This temporary contraction gives time for platelets and clotting factors to act.
Stage 2: Platelet Plug Formation (Primary Hemostasis)
When the vessel wall is damaged, collagen fibers are exposed.
Platelets adhere to the damaged site and become activated.
Activated platelets release ADP, serotonin, and thromboxane A , which attract more platelets.
₂
The platelets form a temporary plug that closes small breaks in the vessel.
Stage 3: Blood Coagulation (Secondary Hemostasis)
Damaged tissues release tissue thromboplastin (Factor III).
With the help of calcium ions (Ca² ) and other factors, Prothrombin Activator is formed.
⁺
Prothrombin → Thrombin
Thrombin converts Fibrinogen → Fibrin threads.
Fibrin threads form a meshwork that traps RBCs and platelets, creating a stable clot.
?????? 4
️
⃣ Clot Retraction and Fibrinolysis
After clot formation, platelets contract, pulling the wound edges together (Clot Retraction).
Later, the enzyme Plasmin dissolves the clot (Fibrinolysis) once healing begins.
?????? 5
️
⃣ Role of Calcium and Vitamin K
Calcium ions (Factor IV) are essential in almost all steps of coagulation.
Vitamin K helps the liver form clotting factors II, VII, IX, and X.
?????? 6
️
⃣ Clinical Significance
Hemophilia A – Deficiency of Factor VIII
?????? 1
️
⃣ Introduction
When a blood vessel is injured, bleeding starts immediately.
The body activates a natural process called hemostasis to stop bleeding and prevent blood loss.
It involves the blood vessels, platelets, and plasma clotting factors.
?????? 2
️
⃣ Definition
Hemostasis is the physiological process by which bleeding is stopped after injury.
It includes three stages:
1. Vascular spasm
2. Platelet plug formation
3. Blood coagulation
?????? 3
️
⃣ Stages of Hemostasis
Stage 1: Vascular Spasm (Vasoconstriction)
When a blood vessel is cut, the smooth muscles in its wall contract.
This narrows the vessel and reduces blood flow to the injured area.
This temporary contraction gives time for platelets and clotting factors to act.
Stage 2: Platelet Plug Formation (Primary Hemostasis)
When the vessel wall is damaged, collagen fibers are exposed.
Platelets adhere to the damaged site and become activated.
Activated platelets release ADP, serotonin, and thromboxane A , which attract more platelets.
₂
The platelets form a temporary plug that closes small breaks in the vessel.
Stage 3: Blood Coagulation (Secondary Hemostasis)
Damaged tissues release tissue thromboplastin (Factor III).
With the help of calcium ions (Ca² ) and other factors, Prothrombin Activator is formed.
⁺
Prothrombin → Thrombin
Thrombin converts Fibrinogen → Fibrin threads.
Fibrin threads form a meshwork that traps RBCs and platelets, creating a stable clot.
?????? 4
️
⃣ Clot Retraction and Fibrinolysis
After clot formation, platelets contract, pulling the wound edges together (Clot Retraction).
Later, the enzyme Plasmin dissolves the clot (Fibrinolysis) once healing begins.
?????? 5
️
⃣ Role of Calcium and Vitamin K
Calcium ions (Factor IV) are essential in almost all steps of coagulation.
Vitamin K helps the liver form clotting factors II, VII, IX, and X.
?????? 6
️
⃣ Clinical Significance
Hemophilia A – Deficiency of Factor VIII
Hemophilia B – Deficiency of Factor IX
Vitamin K deficiency – Delayed clotting
Thrombocytopenia – Low platelet count → excessive bleeding
?????? 7
️
⃣ Flow Chart – Mechanism of Hemostasis
Injury to Blood Vessel
↓
Vasoconstriction (Vascular Spasm)
↓
Platelet Adhesion & Plug Formation
↓
Release of Thromboplastin (Tissue Factor)
↓
Formation of Prothrombin Activator
↓
Prothrombin → Thrombin (in presence of Ca² )
⁺
↓
Fibrinogen → Fibrin (by Thrombin)
↓
Formation of Fibrin Mesh (Blood Clot)
↓
Clot Retraction → Fibrinolysis → Healing
?????? 8
️
⃣ Conclusion
Hemostasis is the body’s natural mechanism to stop bleeding and protect from blood loss.
It involves the coordinated action of vessels, platelets, clotting factors, calcium, and vitamin K.
Vitamin K deficiency – Delayed clotting
Thrombocytopenia – Low platelet count → excessive bleeding
?????? 7
️
⃣ Flow Chart – Mechanism of Hemostasis
Injury to Blood Vessel
↓
Vasoconstriction (Vascular Spasm)
↓
Platelet Adhesion & Plug Formation
↓
Release of Thromboplastin (Tissue Factor)
↓
Formation of Prothrombin Activator
↓
Prothrombin → Thrombin (in presence of Ca² )
⁺
↓
Fibrinogen → Fibrin (by Thrombin)
↓
Formation of Fibrin Mesh (Blood Clot)
↓
Clot Retraction → Fibrinolysis → Healing
?????? 8
️
⃣ Conclusion
Hemostasis is the body’s natural mechanism to stop bleeding and protect from blood loss.
It involves the coordinated action of vessels, platelets, clotting factors, calcium, and vitamin K.
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