ENDROCRINE_SYSTEM_PRESENTATION-1(1).pptx

The endocrine system is a complex network of glands that produce and release hormones directly into the bloodstream to regulate various body functions, including growth, metabolism, reproduction, and mood. The major glands of the endocrine system include the pituitary gland, hypothalamus, thyroid gland, parathyroid glands, adrenal glands, pancreas, and gonads (ovaries and testes). The pituitary gland, known as the "master gland," is located at the base of the brain and controls other endocrine glands, regulating growth, metabolism, and reproductive functions. The hypothalamus, located in the brain, connects the nervous system to the endocrine system and regulates vital functions such as temperature, hunger, and thirst. The thyroid gland, located in the neck, produces hormones that regulate metabolism and influence growth and development. The parathyroid glands, four small glands behind the thyroid, regulate calcium levels in the blood. The adrenal glands, located on top of each kidney, produce hormones that help regulate metabolism, the immune system, blood pressure, and the stress response. The pancreas, located behind the stomach, produces insulin and glucagon to regulate blood sugar levels. The gonads, which include the ovaries and testes, produce sex hormones that regulate reproductive functions and secondary sexual characteristics. Hormones act as messengers, released into the bloodstream to affect target organs and tissues, maintaining homeostasis and regulating physiological activities. The endocrine system is essential for maintaining internal balance and influences mood, energy levels, and overall health. Dysfunction in the endocrine system can lead to various disorders, highlighting its critical role in the body.

1. SYSTEM ENDOCRINE

2. FUNCTIONS Metabolism. regulation of blood glucose Tissue development Ion regulation. Control of food intake and digestion. Immune system regulation. Water balance. Heart rate and blood pressure regulation. Uterine contraction and milk release.

3. Characteristics of the Endocrine System Hormones – chemical messenger that is secreted into the blood. Endocrine System – composed of endocrine glands + endocrine specialized cells. Endocrine – Greek word; endo (within) + krino (secrete); ductless glands that directly secretes their products into the blood stream. Exocrine glands – have ducts that carry their secretions to the outside of the body; drains their secretions through a duct to the outside of the body or into a holloworgan. Endocrinology – study of the endocrine system

4. 01 02 03 endocrin e system composed of endocrin gland an specialized endocrin e cell locate throughout the body. Endocrine gland and a cell secret minute amount of chemica l messenger called hormones into the bloodstream, rather than i nto a duct. Hormone then travel through the general blood circulation to target cell or effector. the only hormones that will bind into the ( ) is the one that will fit into the receptor of the target cell

5. Chemical messengers allow cells to communicate with each other PRINCIPLES OF CHEMICAL COMMUNICATION Secretion- controlled release of chemicals from a cell

6. Classes of Chemical Messengers

7. HORMONES Hormones are chemical messengers that are secreted directly to the blood stream by endocrine glands or specialized endocrine cells. From the blood stream, they travel to the effectors or target cells to produce a response.

8. General Characteristics of Hormones Hormones share several characteristics: 1. Stability - For hormones to activate their targets continuously, they must remain active in the circulation long enough to arrive at their target cells. 2. Communication- Hormones must be able to interact with their target tissue in a specific manner in order to activate a coordi- nated set of events. 3. Distribution Hormones are transported by the blood to many locations and therefore have the potential to activate any cell in the body, including those far away from where they were produced. Their chemical nature does not allow them to easily dissolve in the plasma. Thus, some hormones require a chaperone, which binds to and protects hormones so that they arrive safely at their target. Hormones requiring a transport chaperone bind to blood proteins called binding proteins . Once hormones attach to a binding protein they are then called bound hormones.

9. Chemical Nature of Hormones Water-soluble hormone include protein, peptide, amino acid most common example - growt hormon, antidiuretic, prolactin Lipid-soluble hormone include steroid and eicasanoids example - LH, FSH, androgen

10. Patterns of Hormone Secretion As a result of the variation in transport and removal of lipid- soluble hormones and water-soluble hormones, the blood levels of hormones differ. In addition, blood levels of hormones are further determined by the overall pattern of secretion. The three main patterns of hormone secretion are chronic, acute, and episodic

11. ■ Chronic hormone secretion results in relatively constant blood levels of hormone over long periods of time. This type of secretion is exemplified by thyroid hormones, which circulate in the blood within a small range of concentrations.

12. Acute hormone secretion occurs when the hormone’s concentration changes suddenly and irregularly, and its circulating levels differ with each stimulus. This secretion pattern is represented by the amino acid derivative epinephrine, which is released in large amounts in response to stress or physical exercise.

13. ■ Episodic hormone secretion occurs when hormones are se- creted at fairly predictable intervals and concentrations. This pattern is often observed in steroid reproductive hormones, which fluctuate over a month in cyclic fashion during the human reproductive years.

14. control of Hormone Secretion

15. Three types of stimuli regulate hormone release: humoral, neural, and hormonal. No matter what stimulus releases the hormone, however, the blood level of most hormones fluctuates within a homeostatic range through negative-feedback mechanisms.

16. Control by Humoral Stimuli Metabolites and other molecules in the bloodstream can directly stimulate the release of some hormones. These molecules are referred to as humoral stimuli because they circulate in the blood, and the word humoral refers to body fluids, including blood. Stimulation of Hormone Release

17. The second type of hormone regulation involves neural stimuli of endocrine glands. Following action potentials, neurons release a neurotransmitter into a synapse with hormone-producing cells, these cases, the neurotransmitter stimulates the cells to secrete their hormone. Control by Neural Stimuli

18. The third type of regulation uses hormonal stimuli. It occurs when hormones stimulate the secretion of other hormones. The most common examples are hormones from the anterior pituitary gland, called tropic (trō′pik) hormones. Control by Hormonal Stimuli

19. INHIBITION OF HORMONE RELEASE • A process that occurs to counteract the stimulating effect of three types of stimuli: humoral, neural, and hormonal. 1. Humoral inhibition - opposes and counteract the effect of humora stimulus 2. Neural inhibition: inhibitor neurotransmitters prevents the endocrine gland from secreting it hormone 3. Hormonal inhibition: certain hormones block the release of other hormones. ❖ Inhibiting hormones are produced by the hypothalamus to prevent the pituitary gland to release tropic hormones.

20. Negative Feedback Loop • Regulates hormone secretion by the hypothalamus and pituitary gland • Increased amounts of target gland hormones in the bloodstream decrease secretion of the same hormone and other hormones that stimulate its release

21. Positive feedback Some hormones, when stimulated by a tropic hormone, promote the further synthesis and secretion of the tropic hormone in addition to stimulating their target cell. In turn, this stimulates even more secretion of the original hormone. Thus, it is a self-propagating system

22. Receptors – where hormones exert action by binding to proteins Receptor site – the portion of each receptor molecule where a hormone bind Specificity – tendency of hormones to bind to the type of receptor Target tissue – the responding tissue based on the hormone released

23. HORMONE RECEPTORS and MECHANISM OF ACTION

24. Target tissues’ sensitivity to hormone levels can change, for various reasons. Changing the receptor number at a target ensures an optimal target tissue response to a hormone. For example, the response of some target tissues rapidly decreases over time through desenitization. This happens because the cells’ nutrient and energy supplies become depleted, causing the cells to lose the ability to respond to the hormone. Decrease in Receptor Number

25. Increase in Receptor Number Up-regulation results in an increase in the rate of receptor synthesis in the target cells, which increases the total number of receptor molecules in a cell. An example of up-regulation is a process that occurs to stimulate ovulation of the oocyte. During each menstrual cycle, there are an increased number of receptors for luteinizing hormone (LH) in ovary cells. Follicle-stimulating hormone (FSH) secreted by the pituitary gland increases the rate of LH receptor synthesis in ovary cells.

26. CLASSES OF RECEPTORS 1. L ipid-soluble hormones bind to nuclear receptors. ❖ Interaction with cell DNA to regulate transcription. 2. W ater-soluble hormones bind to membrane bound receptors. ❖ Hormone receptor complex initiates a response inside the cell (G proteins, cAMP, protein kinase).

27. LIPID-SOLUBLE HORMONE Lipid-soluble hormones include steroids, thyroid hormones, and some fatty acid derivatives. Most lipid-soluble hormones are transported bound to binding proteins. Thus, their half-life extends from minutes to weeks. Lipid-soluble hormones are removed from the circulation by conjugation to sulfate or glucuronic acid, which then allows them to be excreted in the bile.

28. LIPID-SOLUBLE HORMONE Lipid-soluble hormones include steroids, thyroid hormones, and some fatty acid derivatives. Most lipid-soluble hormones are transported bound to binding proteins. Thus, their half-life extends from minutes to weeks. Lipid-soluble hormones are removed from the circulation by conjugation to sulfate or glucuronic acid, which then allows them to be excreted in the bile.

29. (a) Lipid-soluble hormones diffuse through the plasma membrane of their target cell and bind to a cytoplasmic receptor or a nuclear receptor. In the nucleus, the combination of the hormone and the receptor initiates protein synthesis,

30. (b) Water-soluble hormones bind t o the external portion of membrane-bound receptors, which are integral membrane proteins on their target cell

31. Action of Nuclear Receptors 1. Nuclear receptors have portions that allow them to bind to the DNA in the nucleus once the hormone is bound. The hormone-receptor complex activates genes, which in turn activate the DNA to produce mRNA. The mRNA increases the synthesis of certain proteins that produce the target cell’s response. 2. Nuclear receptors cannot respond immediately, because it takes time to produce the mRNA and the protein.

32. Membrane-Bound Receptors and Signal Amplification 1. Membrane-bound receptors activate a cascade of events once the hormone binds. 2. Some membrane-bound receptors are associated with membrane proteins called G proteins. Hormone binds to a membrane-bound receptor, and G proteins are activated. The α subunit of the G protein binds to ion channels and causes them to open or change the rate of synthesis of intracellular mediators, such as cAMP, cGMP, IP3, and DAG.

33. 3. Intracellular enzymes can be activated directly, which in turn causes the synthesis of intracellular mediators, such as cGMP, or adds a hosphate group to intracellular enzymes, which alters their activity. 4. Second-messenger systems act rapidly, because they act on already existing enzymes to amplify the signal. Membrane-Bound Receptors and Signal Amplification

34. ENDOCRINE GLANDS

35. 1. Regulation of metabolism 2. Control of food intake and digestion 3. Modulation of tissue development 4. Regulation of ion levels 5. Control of water balance 6. Changes in heart rate and blood pressure 7. Control of blood glucose and other nutrients 8. Control of reproductive functions 9. Stimulation of uterine contractions and milk release 10. Modulation of immune system function Rgulatory Functions of the Endocrine System

36. Pituitary Gland and Hypothalamus

37. (a) A midsagittal section of the head through the pituitary gland, showing the location of the hypothalamus of the brain and the pituitary gland. The pituitary gland is in a depression called the sella turcica in the floor of the skull. It is connected to the hypothalamus by the infundibulum.

38. (b) The pituitary gland is divided into the anterior pituitary gland and the posterior pituitary gland. The posterior pituitary consists of the enlarged distal end of the infundibulum, which connects the posterior pituitary to the hypothalamus

39. Located in the limbic system of the brain Almond-sized, cone-shaped gland, located below the thalamus and above the pituitary gland and brain stem It is responsible for controlling pituitary hormone secretion It is considered the link between nervous system and endocrine system It produces releasing and inhibiting hormones, which stop and start the production of hormones throughout the body The hypothalamus is involved with maintenance of homeostasis Hypothalamus

40. Growth hormone–releasing hormone (GHRH) A small peptide that stimulates the secretion of growth hormone from the anterior pituitary gland, and growth hormone–inhibiting hormone (GHIH), also called somatostatin, is a small peptide that inhibits growth hormone secretion 2. Thyrotropin-releasing hormone (TRH) A smallpeptide that stimulates the secretion of thyroid-stimulating hormone from the anterior pituitary gland. Hormones secreted by the Hypothalamus

41. 3. Corticotropin-releasing hormone (CRH) A peptide that stimulates the secretion of adrenocorticotropic hormone from the anterior pituitary gland 4. Gonadotropin-releasing hormone (GnRH) A small peptide that stimulates the secretion of both luteinizing hormone and follicle-stimulating hormone from the anterior pituitary gland. 5. Prolactin-releasing hormone (PRH) and prolactin-inhibiting hormone (PIH) Regulates the secretion of prolac_x0002_tin from the anterior pituitary gland Hormones secreted by the Hypothalamus

42. The posterior pituitary is composed of neural tissue. Thus, the hormones stored and secreted by the posterior pituitary gland are the neurohormones, antidiuretic hormone and oxytocin. A separate population of neurons secretes each neurohormone. Posterior Pituitary Gland (Nuerohyphophysis)

43. 1. Antidiuretic Hormone A water conservation hormone ADH prevents (anti-) the output of large amounts of urine (diuresis). An alternate name for ADH is vasopressin because it also constricts blood vessels and raises blood pressure when large amounts are released. Hormones secreted by the Posterior Pituitary Gland

44. 2. Oxytocin An important reproductive hormone, synthesized by the hypothalamic neurosecretory neuron cell bodies in the paraventricular nuclei. Oxytocin stimulates labor in pregnant mammals. It does this by stimulating smooth muscle contraction in the uterus. This neurohormone plays an important role in the birth of a baby during delivery. It also causes contraction of uterine smooth muscle in nonpregnant women, primarily during menstruation and sexual intercourse. Hormones secreted by the Posterior Pituitary Gland

45. Oxytocin is responsible for milk letdown in breastfeeding moms and other lactating mammals. Although little is known about the specific effects of oxytocin in males, evidence suggests that it promotes sperm movement during ejaculation and pair bonding. Hormones secreted by the Posterior Pituitary Gland

46. Anterior pituitary hormones are regulated by releasing and inhibiting hormones. These hormones pass from the hypothalamus through the hypothalamohypophysial portal system to the anterior pituitary and influence anterior pituitary secretions. For some anterior pituitary hormones, the hypothalamus produces both releasing hormones and inhibiting hormones. For others, regulation is primarily by releasing hormones. Anterior Pituitary Gland (Adenohyphophysis)

47. 1. Growth Hormone (GH) Sometimes called somatotropin. GH stimulates growth in most tissues and regulates metabolism. GH stimulates the uptake of amino acids and their conversion into proteins and stimulates the breakdown of lipids and the synthesis of glucose. GH stimulates the production of somatomedins; together, they pro_x0002_mote bone and cartilage growth. GH secretion increases in response to an increase in blood amino acids, low blood glucose, or stress. GH is regulated by GHRH and GHIH or by somatostatin. Hormones secreted by the Anterior Pituitary Gland

48. 2. Thyroid Stimulating Hormone or thyrotropin Causes the release of thyroid hormones 3. Adenocorticotropic Hormone Derived from proopiomelanocortin; it stimulates cortisol secretion from the adrenal cortex and increases skin pigmentation. 4. Gonadotrophins: A. Luteinizing Hormone Females: stimulates ovulation and estrogen production Males: stimulates testosterone production Hormones secreted by the Anterior Pituitary Gland

49. B. Follicle Stimulating Hormone Females: stimulates estrogen production and maturation of the ova Males: stimulates sperm production 5. Prolactin Stimulates milk production in lactating females. Prolactin_x0002_releasing hormone (PRH) and prolactin-inhibiting hormone (PIH) from the hypothalamus affect prolactin secretion. Hormones secreted by the Anterior Pituitary Gland

50. Thyroid Gland

51. The thyroid gland synthesizes and secretes three hormones. It is composed of two lobes connected by a narrow band of thyroid tissue called the isthmus. It is the largest gland and it requires iodine to function. It secretes 2 hormones, namely: thyroid hormone and calcitonin. Thyroid Gland

52. 1. The thyroid hormones include triiodothyronine , commonly called T3, and tetraiodothyronine . A more common name for tetraiodothyronine is thyroxine, or even more commonly T4. T4 is the precursor for T3, and both are major secretory products of the thyroid gland, consisting of 10% T3 and 80% T4, respectively. Both regulate metabolic rates and are needed for growth. 2. Calcitonin An increase in blood calcium levels stimulates calcitonin secretion by the parafollicular cells. Calcitonin decreases blood calcium and phosphate levels by inhibiting osteoclasts. Hormones secreted by the Thyroid Gland

53. 1. T3 and T4 synthesis occurs in thyroid follicles. Iodide ions are taken into the follicles by active transport, oxidized, and bound to tyrosine molecules in thyroglobulin. Thyroglobulin is secreted into the follicle lumen. Tyrosine molecules with iodine combine to form T3 and T4 thyroid hormones. Thyroglobulin is taken into the follicular cells and broken down; T3 and T4 diffuse from the follicles to the blood. 2. T3 and T4 are transported in the blood. T3 and T4 bind to thyroxine-binding globulin and other plasma proteins. The plasma proteins prolong the half-life of T3 and T4 and regulate the levels of T3 and T4 in the blood. Approximately one-third of the T4 is converted into functional T3. T3 and T4 Synthesis

54. 3. T3 and T4 bind with nuclear receptor molecules and initiate new protein synthesis. 4. T3 and T4 affect nearly every tissue in the body. T3 and T4 increase the rate of glucose, lipid, and protein metabolism in many tissues, thus increasing body temperature. Normal growth of many tissues is dependent on T3 and T4. 5. TRH and TSH regulate T3 and T4 secretion. Increased TSH from the anterior pituitary increases T3 and T4 secretion. TRH from the hypothalamus increases TSH secretion. TRH increases as a result of chronic exposure to cold, food deprivation, and stress. T3 and T4 inhibit TSH and TRH secretion. T3 and T4 Synthesis

55. Parathyroid Gland

56. 1.The parathyroid glands are embedded in the thyroid gland. 2. Parathyroid Hormone increases blood calcium levels. PTH stimulates osteoclasts. PTH promotes calcium reabsorption by the kidneys and the forma_x0002_tion of active vitamin D by the kidneys. Active vitamin D increases calcium absorption by the intestine. 3. A decrease in blood calcium stimulates PTH secretion. Parathyroid Gland and Hormone secreted

57. Adrenal Gland

58. The adrenal glands are near the superior poles of the kidneys. The adrenal medulla arises from neural crest cells and functions as part of the sympathetic nervous system. The adrenal cortex is derived from mesoderm. The adrenal medulla is composed of closely packed cells. The adrenal cortex is divided into three layers: the zona glomerulosa, the zona fasciculata, and the zona reticularis. Adrenal Gland

59. Hormones secreted by the Adrenal Medulla 1. Epinephrine (accounts for 80%) Epinephrine increases blood glucose levels, the use of glycogen and glucose by skeletal muscle, and heart rate and force of contraction. It also causes vasoconstriction in the skin and viscera and vasodilation in skeletal and cardiac muscle. 2. Norepinephrine (accounts for 20%) Norepinephrine and epinephrine stimulate cardiac muscle and cause the constriction of most peripheral blood vessels.

60. Hormones secreted by the Adrenal Cortex 1. The zona glomerulosa secretes the mineralocorticoids , especially aldosterone. Aldosterone acts on the kidneys to increase sodium and to decrease potassium and hydrogen levels in the blood. 2. The zona fasciculata secretes glucocorticoids , especially cortisol. Cortisol increases lipid and protein breakdown, increases glucose synthesis from amino acids, decreases the inflammatory response, and is necessary for the development of some tissues.

61. Hormones secreted by the Adrenal Cortex 3. The zona reticularis secretes androgens. In females, androgens stimulate axillary and pubic hair growth and sex drive.

62. Pancreas

63. 1. The pancreas, located along the small intestine and the stomach, is both an exocrine and an endocrine gland. 2. The exocrine portion of the pancreas consists of a complex duct sys_x0002_tem, which ends in small sacs, called acini, that produce pancreatic digestive juices. 3. The endocrine portion consists of the pancreatic islets. Each islet is composed of alpha cells, which secrete glucagon; beta cells, which secrete insulin; and delta cells, which secrete somatostatin. Pancreas

64. Hormones secreted by the Pancreas 1. Insulin Insulin’s primary function is to lower blood glucose levels by stimulating glucose transport into body cells It is secreted when blood glucose is elevated, such as after a meal. 2. Glucagon Glucagon is the companion hormone to insulin. Its secretion is stimulated when blood glucose levels decline. Glucagon promotes the release of glucose from intracellular stores. For exam_x0002_ple, glucagon primarily influences the liver, although it has some effect on skeletal muscle and adipose tissue

65. 1. The thymus produces thymosin , which is involved in the development of the immune system. 2. The digestive tract produces several hormones that regulate digestive functions. 3. Autocrine and paracrine chemical messengers are produced by many cells of the body and usually have a local effect on body functions. Other Hormones and Chemical Messengers

66. 4. Eicosanoids, such as prostaglandins, prostacyclins, thromboxanes, and leukotrienes, are derived from fatty acids and mediate inflammation and other functions. Endorphins, enkephalins, and dynorphins are analgesic substances. Growth factors influence cell division and growth in many tissues, and interleukin-2 influences cell division in the T cells of the immune system Other Hormones and Chemical Messengers

67. ENDOCRINE SYSTEM DISEASES

68. D iabetes mellitus (DM) results primarily from the inadequate secretion of insulin or the inability of tissues to respond to i nsulin. There are two types of Diabetes: A. Type I DM also called insulin-dependent diabetes mellitus (IDDM) B. Type II DM also called noninsulin-dependent diabetes mellitus (NIDDM) Diabetes Mellitus

69. Type I and Type II Diabetes Mellitus a. Type I DM Affects approximately 5–10% of people with diabetes mellitus and results from diminished insulin secretion. It develops as a result of autoimmune destruction of the pancreatic islets, and symptoms appear after approximately 90% of the islets have been destroyed. Type 1 diabetes mellitus most commonly develops in young people. Heredity may play a role in the condition, although the initiation of pancreatic islet destruction may involve a viral infection of the pancreas.

70. Type I and Type II Diabetes Mellitus B. Type II DM Results from the inability of tissues to respond to insulin. Type 2 diabetes mellitus usually develops in people older than 40–45 years of age, although it is being observed more frequently in much younger patients. Type 2 diabetes mellitus is more common than type 1 diabetes mellitus. People with type 2 diabetes mellitus have a reduced number of functional receptors for insulin, or one or more of the enzymes activated by the insulin receptor are defective. Thus, glucose uptake by cells is very slow, which results in elevated blood glucose after a meal.

71. Hyperthyroidism happens when the thyroid gland makes too much thyroid hormone. This condition also is called overactive thyroid. Hyperthyroidism speeds up the body's metabolism. That can cause many symptoms, such as weight loss, hand tremors, and rapid or irregular heartbeat. Hyperthyroidism

72. Hypothyroidism, also called underactive thyroid, is when the thyroid gland doesn’t make enough thyroid hormones to meet your body’s needs. The thyroid is a small, butterfly-shaped gland in the front of your neck. Thyroid hormones control the way your body uses energy, so they affect nearly every organ in your body, even the way your heart beats. Without enough thyroid hormones, many of your body’s functions slow down. Hypothyroidism

73. Abnormal Secretion of Growth Hormones Excessive GH secretion causes: Gigantism - Gigantism, also called pediatric acromegaly and pituitary gigantism, is a very rare condition that happens when a child or adolescent has high levels of growth hormone (GH) in their body, which causes them to grow very tall. The pituitary gland normally produces GH, but a tumor on their pituitary can produce excess GH in gigantism.

74. Abnormal Secretion of Growth Hormones Acromegaly - Acromegaly is a hormonal disorder that develops when your pituitary gland produces too much growth hormone during adulthood.When you have too much growth hormone, your bones increase in size. In childhood, this leads to increased height and is called gigantism. But in adulthood, a change in height doesn't occur. Instead, the increase in bone size is limited to the bones of your hands, feet and face, and is called acromegaly.

75. Cushing’s Syndrome Cushing’s syndrome is a disorder that occurs when your body makes too much of the hormone cortisol over a long period of time. Cushing’s syndrome most often affects adults, usually aged 30 to 50, but can also occur in children. Cushing’s syndrome affects about three times as many women as men. In people who have type 2 diabetes and blood glucose levels that stay too high over time, along with high blood pressure, Cushing’s syndrome may be the cause. People who take medicines called glucocorticoids, which are similar to cortisol, also can develop Cushing’s syndrome.

76. Reference Seeley’s Anatomy and Physiology Eleventh Edition

77. Members : Dela Cruz Aileen Narag , Micah Taloza Christelle Joy