Chemical coordination

2nd year

1. CHEMICAL COORDINATION “ It is the type of coordination present between the cells or different organs within the body of multicellular organisms. In this kind of coordination a group of cells releases specific chemicals, which regulates the activities of other cell of the body.”

2. Endocrine system

3. ENDOCRINE SYSTEM DEFINITION Endocrine glands  are organs in the body that produce hormones which are released directly into the bloodstream. Together these glands make up the endocrine system, which performs essential functions like regulating metabolism, growth and reproduction .

4. INTRODUCTION Endocrine derives from the Greek words endo meaning inside , within , and crinis for secrete Chemicals are released by these glands(hormones) hormone derived from Greek word which means ‘ to excite’ The field of study dealing with the endocrine system and its disorders is endocrinology , a branch of internal medicine . In animals glands are of two types Exocrine gland : release products (enzymes) into DUCTS Ex) Sweat, digestive juices Endocrine glands :– directly to bloodstream; NO DUCTS Ex) Hormones Features of endocrine gland : their ductless nature their vascularity , the presence of intracellular vacuoles or granules storing their hormones.

5. Endocrine system vs. nervous system Endocrine system Effects are slow to initiate Response are prolonged (few hrs to week) HORMONES released in blood stream Nervous system Effects very fast and quick Responses are short lived. NEUROTRANSMITTERs travel through neurons released in synaptic cleft

6. CHEMICAL CLASSIFICATION OF HORMONES Peptide/ Protein Steroid Amine (modified amino acids e.g. Thyroxine, Epinephrine, Norepinephrine) PEPTIDE HORMONE May occur as short chain of amino acids e.g., ADH, Oxytocin Or occur as long chain amino acid e.g. Glucagon, Insulin, Prolactin Not lipid soluble Received by receptors external to the cell membrane STEROID HORMONE They are lipid soluble Diffuse easily through the membrane

7. Hormone Actions PEPTIDE HORMONE React with specific receptors outside the cell This triggers an enzyme reaction with lead to the formation of a second messenger (cAMP). cAMP can produce specific intracellular functions: Activates cell enzymes Change in membrane permeability Promote protein synthesis Change in cell metabolism Stimulation of cell secretions

8. Hormone Actions Steroid Hormones Pass through the cell membrane Binds to specific receptors Then enters the nucleus to bind with the DNA which then activates certain genes (Direct gene activation). mRNA is synthesized in the nucleus and enters the cytoplasm and promotes protein synthesis for: Enzymes as catalysts Tissue growth and repair Regulate enzyme function

9. Endocrine Glands Hypothalamus Pituitary Anterior lobe Posterior lobe Thyroid gland Parathyroid glands Adrenal Glands Cortex Medulla Islets of Langerhans Gonads Ovaries Testes Pineal gland Thymus others Hormonal Communication

10. Hypothalamus Neuroendocrine organ Central part of brain attached by numerous nerves to pituitary gland Weight is about 4g(human) Control the pituitary gland by producing chemicals (releasing/stimulating or inhibiting hormones) Maintains homeostasis(heart rate, body temperature, water balance, and the secretions of the pituitary gland)

11. Pituitary gland(Hypophysis) Pea size gland hang from the base of brain by stalk (infundibulum) loge in the bone of skull, weigh is about 5gm In past considered as master gland but it itself under the control of hypothalamus It consists of a hormone-producing glandular portion Have two lobes 1.Anterior pituitary (Adenohypophysis ) 2.Posterior pituitary (Neurohypophysis)

12. Anterior pituitary –hypothalamus (Adenohypophysis) It Secretes six regulating hormone (tropic hormone) Thyroid stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Follicle stimulating hormone (FSH ) Luteinizing hormone (LH) Growth / somatotropin hormone ( GH /STH) Prolactin Melanocyte stimulating hormone (MSH)

13. Anterior P. Homeostatic Imbalances Growth / Somatotropin hormone (GH) I t is a non- trophic,anabolic hormone which simulates the growth of all body tissue specially skeletal muscles ,bone and cartilage. Control protein synthesis and general metabolism I mbalances Hyperseretion in childhood produces gigantism Hyperseretion after adult-hood produces acromegaly Hypo secretion in childhood produces dwarfism

14. Posterior Pituitary or Neurohypophysis Neurohypophysis It does not synthesize hormones, however, it stores and releases two hormones produced by the neurosecretory cells of the hypothalamus It is an extension of hypothalamus Antidiuretic hormone (ADH) Oxytocin

15. Pituitary—Posterior lobe Oxytocin Stimulates smooth muscle contraction of uterus at labour Stimulates mammary glands during lactation. Antidiuretic H . Stimulates water reabsorption in collecting ducts. Decreases urine output Hypo secretion of ADH produces diabetes insipidus Excessive thirst and urination

16. Thyroid Gland Located at the base of neck in front of trachea Bilobed and butterfly shaped Weigh about 25-40gm Composed of follicles which produce Thyroxine ( TetraiodothyronineT 4 ) Triiodothyronine (T 3 ) Calcitonin Both T 3 and T 4 are important in controlling metabolism and are essential for normal physical growth and mental development. Calcitonin causes excess blood calcium to be deposited in bones.

17. Homeostatic imbalances Hypothyroidism results Myxedema (in adults)lethargy, weight gain, dry- skin, hair loss, cold intolerant, confused and depressed. Goiter— low intake of iodine in diet Cretinism (in children)mental retardation,dwarfism,lack of sexual maturity. Hyperthyroidism results Graves disease (enlargement of overall gland along with E xopthalamic goiter(excess accumulation of fat and mucus in eye orbit)

18. Parathyroid Glands Two pairs of pea-sized glands embedded on the surface of thyroid Weigh about 0.05g-0.3g Parathyroid hormone (PTH) Antagonistic to C alcitonin Stimulated by falling Ca 2+ in blood and inhibited by rising blood Ca 2+ Stimulates osteoclasts to free Ca 2+ from bone Stimulates Ca 2+ uptake from intestine & kidney

19. Pancreas Consists of two major types of secretory tissues which reflects its dual function Exocrine gland secretes digestive juice Endocrine gland releases hormones Patches of pancreatic cells (Islets of Langerhans) secretes Insulin from beta cells in response to high blood glucose level Glucagon from a lpha cells in response to low blood glucose level

20. Adrenal gland/ suprarenal gland Triangular structure located at the top of kidney Weight of each gland is 5gm Have two parts Adrenal medulla Adrenal cortex Adrenal cortex produces three kinds of steroid hormones Glucocorticoid(cortisol) Mineralocorticoid (aldosterone ) Small amount of sex hormone (Androgens) .

21. Adrenal cortex Cortex Activity stimulated by ACTH Controls prolonged responses by secreting corticosteroids. Glucocorticoid(Cortisol)  regulate glucose metabolism and the immune system. Mineralocorticoids(Aldosterone)  regulate salt and water balance Gonad corticoids(Androgens) development of secondary sexual characteristics in male like growth of facial hair and deepening of voice.  It is produced in both sexes and its excessive secretion in females causes masculinization i.e,appearance of beard

22. Adrenal Cortex Imbalances Hyper secretion leads to Cushing’s Disease Weight gain Hypertension Reduced sex drive Diabetes Depression/inability to think clearly Hypo secretion leads to Addison’s Disease Fatigue , weakness, loss of appetite Weight loss Gastrointestinal problems (nausea, vomiting, etc.) Darkening of the skin Low blood pressure and low blood sugar

23. Adrenal Medulla Medulla The adrenal medulla mediates short–term responses under the influence of sympathetic nervous system . It secretes two emergency hormones under stress conditions to bring about fight or flight response. Epinephrine (adrenaline) increases blood glucose, heart beat, breathing rate and metabolic rate. directs blood to the heart, brain, and skeletal muscles. Norepinephrine (noreadrenaline ) Works like epinephrine Sustains blood pressure

24. Pancreas Homeostatic Imbalances Diabetes TYPE I Diabetes Beta cells are destroyed by lymphocytes as a result of autoimmune disorder. No insulin is produced. TYPE II (Diabetes mellitus) Insulin is produced Target cells lose insulin receptors Excess glucose excreted in urine As a result of fat metabolism ketone bodies accumulates in blood Blood Level Regulation in Diabetics

25. Thymus gland It is present in the upper part of chest behind the breast bone. It consists of two lobes that join infront of trachea. It secretes a hormone, Thymosin ,   which stimulates the development and differentiation of T lymphocytes after they leave the thymus. It plays a role in regulating the immune system by stimulating other kinds of immune cells.

26. Pineal gland It is a tiny cone-shaped body located in diencephalon (fore brain) It secretes Melatonin which Influences growth and development of gonads Controls Day/night cycles Timing of sleep, body temperature, appetite Participates in setting the body’s clock

27. Gonads Ovaries Estrogens Maintains female reproductive cycle Development of secondary sexual characters Progesterone Preparation and maintenance of uterus for the development of embryo Testes Testosterone Stimulates bones and muscles growth Development of secondary sexual characters