Endocrine System in the human body- presentation

The endocrine system is a complex network of glands and organs that produce, store, and secrete hormones. These hormones are chemical messengers that regulate various functions in the body, including metabolism, growth, development, tissue function, sexual function, reproduction, sleep, and mood, among other things.

Overview of the Endocrine System
The endocrine system consists of several key glands and organs, each with specific functions:

Hypothalamus: Located in the brain, it links the nervous system to the endocrine system via the pituitary gland. It controls body temperature, hunger, thirst, fatigue, sleep, and circadian cycles.
Pituitary Gland: Often termed the “master gland,” it controls other endocrine glands and regulates growth, blood pressure, and water balance.
Thyroid Gland: Located in the neck, it produces hormones that regulate metabolism, energy levels, and growth.
Parathyroid Glands: These small glands behind the thyroid regulate calcium levels in the blood.
Adrenal Glands: Located on top of the kidneys, they produce hormones like cortisol and adrenaline, which help control stress responses, metabolism, immune system, and blood pressure.
Pancreas: It has both endocrine and exocrine functions. It regulates blood sugar levels by producing insulin and glucagon.
Gonads (Ovaries and Testes): These produce sex hormones like estrogen, progesterone, and testosterone, which are crucial for reproductive functions and secondary sexual characteristics.
Pineal Gland: Located in the brain, it produces melatonin, which affects sleep patterns.
Functions of the Endocrine System
The endocrine system plays a vital role in maintaining homeostasis and regulating various bodily functions:

Metabolism: Hormones like thyroxine from the thyroid gland regulate the metabolic rate.
Growth and Development: Growth hormone from the pituitary gland stimulates growth in tissues and bones.
Reproduction: Sex hormones regulate reproductive cycles and sexual development.
Stress Response: Cortisol and adrenaline from the adrenal glands help the body respond to stress.
Blood Sugar Regulation: Insulin and glucagon from the pancreas maintain blood glucose levels.
Calcium Homeostasis: Parathyroid hormone regulates calcium levels in the blood.
Hormonal Regulation
Hormones are released into the bloodstream and travel to target organs or tissues, where they bind to specific receptors and trigger a response. This process is tightly regulated through feedback mechanisms:

Negative Feedback: This is the most common mechanism, where an increase in the hormone’s effect leads to a decrease in its production. For example, high levels of thyroid hormones inhibit the release of thyroid-stimulating hormone (TSH) from the pituitary gland.
Positive Feedback: Less common, this mechanism amplifies the response. An example is the release of oxytocin during childbirth, which intensifies contractions.
Common Endocrine Disorders
Diabetes Mellitus: A condition where the body can,t properly.

1. ENDOCRINE SYSTEM

2. OBJECTIVES Define the endocrine system and explain its general function. Explain; How does the endocrine system maintain the Homeostasis in the body. Explain the relationship between nervous system and endocrine system. Distinguish Between endocrine and exocrine glands. Define the term hormone and explain its function and number its types. Describe the mechanisms of steroids and non-steroids hormone action. Explain the regulation and transmitters of hormones. Describe the types, function, location of the glands, and their effects during oversecretion or undersecretion on the body.

3. General Principles – The Central Endocrine Glands General Principles of Endocrinology Overal functions of endocrine system Tropic hormones Complexity of endocrine function Factors affecting & means of plasma hormone regulation Types of endocrine disorders Regulation of target organ responsiveness Hypothalamus and Pituitary Hypothalamus – posterior pituitary relationship Vasopressin, oxytocin Hypothalamus – anterior pituitary relationship Anterior pituitary and hypophysiotropic hormones Endocrine control of Growth Factors influencing growth Direct metabolic functions of growth hormone Bone growth Role of other hormones in growth Pineal Gland and Circadian Rhythms Suprachiasmic nucleus as the master biological clock Functions of Melatonin

4. General Principles – The Peripheral Endocrine Glands Thyroid Gland Anatomy of the thyroid gland Thyroid hormones Adrenal Glands Anatomy of the adrenal gland Adrenocortical mineralocorticoids Adrenocorticoid glucocorticoids Adrenocortical sex hormones Adrenal medullary Endocrine control of fuel metabolism Metabolisn , anabolism, catabolism Energy storage Absorptive and postabsorptive states Endocrine pancreas – insulin and glucagon Metabolic effects of other hormones Endocrine control of calcium metabolism Calcium homeostasis Bone remodeling Parathyroid hormone Calcitonin Vitamin D Relationship of phosphate metabolism to calcium metabolism.

5. DEFINITION OF ENDOCRINE SYSTEM The endocrine system is the collection of glands that produce hormones that regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood, among other things. The word endocrine derives from the Greek words "endo," meaning within, and "crinis," meaning to secrete. Although the hormones circulate throughout the body, each type of hormone is targeted toward certain organs and tissues.

6. The endocrine system gets some help from organs such as the kidney, liver, heart and gonads, which have secondary endocrine functions. The kidney, for example, secretes hormones such as erythropoietin and renin . THE GENERAL FUNCTION

7. How does the endocrine system maintains the HOMEOSTASIS ? Homeostasis is happening constantly in our bodies. We eat, sweat, drink, dance, ea t and yet our body composition remains almost the same. If someone were to draw your blood on ten different days of a month, the level of glucose, sodium, red blood cells and other blood components would be pretty much constant, regardless of your behavior (assuming fasting before drawing blood, of course).

8. How does the endocrine system maintains the homeostasis ? These hormones are sent via the blood to specific spots in the body to control things like blood sugar, heart rate, etc . T . he Endocrine system is responsible for homeostasis. The Endocrine system secrete hormones that the body needs to perform certain functions.

9. How does the endocrine system maintains the homeostasis ? When glands create hormones, they get transported through either the bloodstream or the lymph. Hormones help the body to act or react to any threat to homeostasis. Hormones aid throughout reproduction and birth. They help people sleep and wake up. The adrenal glands give off adrenaline to help a person perform in potential danger, and they release dopamine linked with the body's reward system. In general, the endocrine system plays a major role in helping the body maintain homeostasis because it gives off the messengers to help the body to react to any threats to homeostasis

10. The Nervous system & Endocrine system are both essential to the communication and relay of messages throughout the body. They work together to regulate(Homeostasis) the activities of the other systems. Both systems use chemical signals when they respond to changes that might alter (Homeostasis). RELATIONSHIP BETWEEN NERVOUS SYSTEM & ENDOCRINE SYSTEM.

11. Feature Nervous System Endocrine System Signals Electric impulses Chemical impulses (hormones) Pathways Transmission by neurons Transported by blood Speed of information fast slow Duration of effect Short lived Long lived

12. EXAMPLE: In a fight or flight response, there is a coordination of both the nervous and endocrine systems. The nervous system detects stimuli, either inside or out, for example, danger like an oncoming car about to run someone over, and that in turn sends an impulse to the endocrine system where a response is carried out. The response in this case is the release of adrenaline into the bloodstream, by the endocrine glands called adrenal glands. Once in the bloodstream, this hormone can cause the heart rate to increase, the muscles to become ready to either react to an emergency situation by fighting or by flight

13. THE DIFFERENCE BETWEEN ENDOCRINE AND EXOCRINE GLANDS ENDOCRINE GLAND : a gland that secretes hormones directly into the bloodstream; a ductless gland. EXOCRINE GLAND : a gland that secretes substances into ducts which then leave the body (i.e. sweat/sebaceous glands) or into an internal space or lumen (i.e. digestive glands). ★ Exocrine glands are not part of the endocrine system!

14. DEFINITION OF HORMONES Hormones are chemical substances that act like messenger molecules in the body. After being made in one part of the body, they travel to other parts of the body where they help control how cells and organs do their work.

15. Important Functions of hormones include Growth and development of Prompting cell or tissue Food metabolism Initiating and maintaining sexual development and reproduction Maintaining body temperature Controlling thirst Regulating mood and cognitive functioning

16. TYPES OF HORMONES Hormones are classified by various criteria: •By Proximity of their site of synthesis to their site of action. •By their chemical structure. •By their degree of solubility in aqueous medium.

17. 3 classes of hormones based on proximity of site of Synthesis to Site of Action: Autocrine Hormones : those that act on the same cells that synthesize them. Paracrine Hormones : those that are synthesized very close to their site of action. Endocrine Hormones : those that are synthesized by endocrine glands and transported in the blood to target cells that contain the appropriate receptors.

18. 4 classes of hormones based on chemical structure: 1. Peptides or Protein hormones : made of amino acids joined by peptide bonds. most hormones belong to this group except hormones secreted by the gonads (testis and ovary) and the adrenal cortex. Examples: •Thyrotropin Releasing Hormone (TRH), made up of three amino acid residues. •Insulin, made up of 51 amino acid residues.

19. 2. Steroid hormones . made of fatty acids using cholesterol as a functional group. only hormones secreted by the gonads and adrenal cortex belong to this group . Amino acid derivatives. Fatty acid derivatives.

20. Two classes of hormones based on solubility in aqueous medium:- 1. Hydrophilic Hormones . Hormones that are soluble in aqueous medium. •They cannot cross the cell membrane. Examples : Insulin, Glucagon, Epinephrine.

21. 2 . Lipophilic Hormones. Hormones that are not soluble in aqueous medium, but soluble in lipid They can easily cross the cell membrane, Examples: Thyroid hormones, Steroid hormones Location of receptors for each class of hormone is different.

22. MECHANISM OF HORMONES As there are huge variety of hormones , there are two mechanism by which hormone trigger changes in cells. They are : Direct Gene Activation Second-Messenger System

23. Direct Gene Activation . Steroid hormones use the mechanism of direct gene expression because they are lipid-soluble molecules. First, they diffuse through the plasma membranes of their target cells into their nucleus . Then they binds to a specific hormone receptor it then further binds to specific sites on the cell's DNA Which activates certain genes to transcribe messenger RNA . it then translates in the cytoplasm Resulting in the synthesis of new protein .

24. Second-Messenger System Water soluble and non-steroid hormones are unable to enter targeted cells so they bind to hormone receptor. Which is situated on target cell's plasma membrane and utilize a second -messenger system. The hormone binds to the membrane receptor and activated receptor sets off a series of reaction that activates an enzyme The enzyme in turn, catalyze reactions that produce second messenger molecules also known as cAMP. This promotes typical response of the target cell to hormone.

25. Hormone Regulation: Feedback Mechanisms

26. Most hormones are regulated by feedback mechanisms. A feedback mechanism is a loop in which a product feeds back to control its own production Negative feedback occurs when a product feeds back to . decrease its own production Positive feedback occurs when a product feeds back to increase its own production

27. CONTROL OF HORMONE RELEASE Endocrine Gland Stimuli The stimuli that activate the endocrine organs fall into three major categories—hormonal, humoral, and neural

28. The most common stimulus is a hormonal stimulus, in which endocrine organs are prodded into action by other hormone HORMONAL STIMULI

29. HUMORAL STIMULI Changing blood levels of certain ions and nutrients may also stimulate hormone release

30. In isolated cases, nerve fibers stimulate hormone release, and the target cells are said to respond to neural stimuli. The classic example is sympathetic nervous system stimulation of the adrenal medulla to release norepinephrine and epinephrine during periods of stress NEURAL STIMULI

31. HORMONE TRANSPORT IN BLOOD Hormones flow through the blood and then bind to their receptors within the capillaries or diffuse out to reach the receptors at the target cell. Water insoluble hormones must bind to plasma protein to be carried into the plasma, hormones remain bind to these protein for some time which act as a reservoir for the hormones. Water soluble hormones which can dissolve into the plasma by itself and can easily diffuse out to their site of action. Water soluble hormones act faster in a short period of time .

32. THE PITUITARY GLAND Definition: The main endocrine gland. It is a small structure in the brain . The pituitary gland is about the size of a bean, and it hangs by a stalk from the hypothalamus. It is called the master gland because it produces hormones that control other glands and many body functions including growth. The pituitary consists of the anterior and posterior pituitary. The pituitary glands are made of the anterior lobe and posterior lobe. The anterior lobe produces and releases hormones. The posterior lobe does not produce its own hormones —this is done by nerve cells in the hypothalamus—but it does store & release them into the circulation.

33. The Anterior Pituitary The anterior lobe releases hormones upon receiving releasing or inhibiting hormones from the hypothalamus. These hypothalamic hormones tell the anterior lobe whether to release more of a specific hormone or stop production of the hormone. Anterior Lobe Hormones: Growth hormone (GH): GH is essential in early years to maintaining a healthy body composition and for growth in children. In adults, it aids healthy bone and muscle mass (increases bone and muscle growth) . It also affects fat distribution and increases protein synthesis . Prolactin (PRL) : Prolactin stimulates breast milk production after childbirth.

34. Follicle-stimulating hormone (FSH): FSH works with LH to ensure normal functioning and development of the ovaries and testes. It stimulates the production of egg and sperm. Luteinizing hormone (LH): LH works with FSH to ensure normal functioning of the ovaries and testes. It triggers ovulation in females and stimulates testosterone production in male. Adrenocorticotropic hormone (ACTH): ACTH stimulates the adrenal glands to produce hormones. Thyroid-stimulating hormone (TSH): TSH stimulates the thyroid gland to produce hormones.

35. The Posterior Pituitary The posterior pituitary (or neurohypophysis) comprises the posterior lobe of the pituitary gland and is part of the endocrine system. The posterior lobe contains the ends of nerve cells coming from the hypothalamus. The hypothalamus sends hormones directly to the posterior lobe via these nerves, and then the pituitary gland releases them. Posterior Lobe Hormones: Antidiuretic hormone (ADH): Antidiuretic hormone, also known as vasopressin, acts to maintain blood pressure, blood volume and tissue water content by controlling the amount of water and hence the concentration of urine excreted by the kidney.This hormone prompts the kidneys to increase water absorption in the blood. Oxytocin: Oxytocin is involved in a variety of processes, such as contracting the uterus during childbirth and stimulating breast milk production.

36. Hypersecretion- Too much of any hormone secreted into the body is usually caused by a secretory pituitary gland tumor. Secretory tumors produce too much prolactin (the hormone that triggers milk production in new mothers), which leads to infertility, discharge from breasts and menstrual abnormality. Some tumors may affect the adrenal glands, due to oversecretion of hormones, which stimulates them and cause a hormone imbalance. Tumors can also make excess of growth hormone which stimulate the thyroid gland, leading to overproduction of the thyroid hormone.Oversecretion of the pituitary hormone human growth hormone can cause gigantism if it occurs before growth of the long bones is complete, or acromegaly if it begins during adulthood.

37. Hyposecretion - Hormones secreted in less amount in the body are commonly caused by a non-secretory pituitary gland tumor, which interferes with the ability of the normal pituitary gland to create hormones. It can, however, also be caused by a large secretory tumor. Hyposecretion can also happen with surgery or radiation therapy for a pituitary gland tumor. Undersecretion of human growth hormone can lead to dwarfism if experienced during childhood, and decreased endocrine function accompanied by lethargy and loss of sexual capacity in the adul t.

38. THE PINEAL GLAND Definition: The pineal gland, also known as the "pineal body," is a small endocrine gland. Location: It is located on the back portion of the third cerebral ventricle of the brain, which is a fluid-filled space in the brain. This gland lies in-between the two halves of the brain. The gland is named for its shape, which resembles a pinecone (in Latin, " pinea ").

39. THE PINEAL GLAND Functions: The pineal gland's function in the body is not clearly understood yet. However , it is known to play a role in regulating female reproduction and sexual maturation. It also has a part in controlling circadian rhythms (biological processes), the body’s internal clock that affects such actions as when we wake and sleep. The pinealocytes create and secrete melatonin , a hormone that helps maintain the body’s internal clock. Melatonin also helps regulate female reproductive hormones, including when women menstruate.

40. THE PINEAL GLAND Oversecretion: The main consequences of swallowing large amounts of melatonin are drowsiness and reduced core body temperature Very large doses have effects on the performance of the human reproductive system (delay in sexual maturation). Undersecretion: Reduced melatonin production is not known to have any effect on health .

41. THYROID GLAND Location : The thyroid gland is located at the base of the throat, just inferior to the Adam’s apple. Structure : It is a fairly large gland consisting of two lobes joined by a central mass, or isthmus . Hormons : Thyroid hormone (thyroxine [T4] and triiodothyronine [T3]) . calcitonin

42. THYROID GLAND Thyroid gland is composed of hollow structures called follicles , which store a sticky colloidal material. Thyroid hormone is derived from this colloid. But calcitonin hormone is made by the parafollicular cells found in the connective tissue between the follicles .

43. THYROID GLAND Thyroxine (T4): is the major hormone secreted by the thyroid follicles. Triiodothyronine (T3): is formed at the target tissues by conversion of thyroxine to triiodothyronine. Each is constructed from two tyrosine amino acids linked together, but thyroxine has four bound iodine atoms, whereas triiodothyronine has three . Function : It is the body’s metabolic hormone Thyroid hormone controls the rate at which glucose is “burned,” or oxidized, and converted to body heat and chemical energy. necessary for normal growth and development.

44. Hyperthyroidism Excessive levels of thyroid hormones in the blood Graves' disease : is an immune system disorder where the thyroid gland enlarges and the eyes may bulge, or protrude anteriorly , high basal metabolic rate, intolerance of heat, rapid heartbeat, weight loss, nervous and agitated behavior, and a general inability to relax.

45. Hyporthyroidism low levels of thyroid hormones in the blood goiter :It is an enlargement of the thyroid gland that results when the diet is deficient in iodine. Cretinism : it results in dwarfism in which adult body proportions remain childlike. Myxedema which is characterized by both physical and mental sluggishness ,Other signs are puffiness of the face, fatigue, poor muscle tone, low body temperature (the person is always cold), obesity, and dry skin. (in adult ).

46. Calcitonin hormone : made by the so-called parafollicular cells found in the connective tissue between the follicles decreases blood calcium levels by causing calcium to be deposited in the bones. It acts antagonistically to parathyroid hormone (PTH) It is released directly to the blood in response to increasing levels of blood calcium.

47. PARATHYROID GLANDS The parathyroid glands are four small glands located on the posterior aspect of the thyroid gland. Low blood levels of calcium stimulate the parathyroid glands to release parathyroid hormone (PTH). It causes bone calcium to be liberated into the blood. PTH also stimulates the kidneys and intestine to absorb more calcium

48. Hyposecretion of PTH results in: tetany : If blood calcium levels fall too low, neurons become extremely irritable and overactive. They deliver impulses to the muscles so rapidly that the muscles go into uncontrollable spasms (tetany), which may be fatal. Hypersecretion leads to extreme bone wasting and fractures. PARATHYROID GLANDS

49. HYPOTHALAMUS The hypothalamus is a secretion of the brain responsible for the production of many of the body's essential hormones .It's not an endocrine gland but regulates the secretion of some pituitary gland hormones. Location: The hypothalamus is located below the thalamus and above the pituitary gland and brain stem

50. Functions of hypothalamus The primary function of the hypothalamus is homeostasis The hypothalamus govern temperature regulation The hypothalamus also governs thirst and hunger It also governs sleep, mood, and blood pressure

51. PANCREAS The pancreas is a large gland that lies alongside the stomach and the small bowel.It is divided into the head, body and tail. Functions of the pancreas It makes digestive juices, which consists of powerful enzyme. It makes hormones that control blood glucose levels

52. Primary hormones secreted by the pancreas include: Gastrin: this hormone aids digestion by stimulating certain cells Glucagon: this helps insulin maintain normal blood glucose by working in the opposite way of insulin Insulin: this hormone regulates blood glucose by allowing many body cell s to absorb and use glucose

53. Diseases and disorders of the pancreas 1. Type 1 diabetes 2. Type 2 diabetes complications Hyperglycemi c coma Hypoglycemi c coma

54. The female and male gonads produce sex cells (an exocrine function). They also produce sex hormones that are identical to those produced by adrenal cortex cells. The major differences from the adrenal sex hormone production are the source and relative amounts of hormones produced. GONADS

55. The female sex organ that serves as an endocrine gland The female gonads or ovaries, are paired, almond-sized organs located in the pelvic cavity. Ovaries produce female sex cells ( ova or eggs) and two groups of steroids hormones estrogens and progesterone . OVARIES

56. PRODUCTION An ovarian follicle (and ovum) start to mature each month following puberty under the influence of FSH (Follicle-stimulating hormone ) .The developing follicle secretes estrogen Luteinizing hormone (LH) causes the follicle to rupture and release the ovum (ovulation); the follicle becomes the corpus luteum. The corpus luteum secretes progesterone

57. FUNCTIONS ESTROGENS The estrogens are responsible for the development of sex characteristics in women ( primarily growth and maturation of the reproductive organs )and the appearance of secondary sex characteristics ( hair in the pubic and axillary regions )at puberty. Acting with progesterone, estrogens promote breast development and cyclic changes in the uterine lining ( the menstrual cycle ).

58. FUNCTIONS PROGESTERONES Progesterone as already noted, acts with estrogen to bring about the menstrual cycle. During pregnancy, it quiets the muscles of the uterus so that an implanted embryo will not be aborted and helps prepare breast tissue for lactation

59. HYPOSECRETION AND HYPERSECRETION OF OVARIAN HORMONES Hyposecretion of the ovarian hormones severely hampers a woman’s ability to conceive and bear children Extreme hypersecretion of ovarian hormones by the ovaries is a rare clinical entity, because excessive secretion of estrogens automatically decreases the production of gonadotropins by the pituitary, and this limits the production of ovarian hormones.

60. The male sex organ that also serves as an endocrine gland The paired oval testes of the male are suspended in a sac, the scrotum, outside the pelvic cavity. Testes produce male sex cells or sperm and male sex hormones testosterone PRODUCTION FSH( follicle-stimulating hormone) causes the production of sperm LH causes the production of testosterone TESTES

61. FUNCTIONS TESTOSTERONE At puberty, testosterone promotes the growth and maturation of the reproductive system organs to prepare the young man for reproduction. It also causes the male’s secondary sex characteristics (growth of facial hair, development of heavy bones and muscles, and lowering of the voice) to appear and stimulates the male sex drive. In adults, testosterone is necessary for continuous production of sperm.

62. HYPOSECRETION OF TESTOSTERONE Leads to a lack of male sex characteristics.There are two types: Primary : This type of hypogonadism (also known as primary testicular failure) originates from a problem in the testicles. Examples: Klinefelter Syndrome, Mumps Orchitis, hemachromatosis Secondary : This type indicates a problem in the Hypothalamus or the pituitary gland. In cases of hyposecretion, the man becomes sterile; such cases are usually treated by testosterone injections.

63. Location : They are flat pyramidal shaped, curved over the top of each kidney. Structure : Although it looks like a single organ, they are actually two endocrine organs; Adrenal Medulla and Adrenal Cortex. Hormones : Epinephrine and norepinephrine are released by adrenal medulla. 3 classes of hormones are released by the adrenal cortex; Mineralocorticoids , Glucocorticoids and sex hormones . ADRENAL GLANDS

64. Function of Adrenal cortex hormones Hormones of Adrenal cortex are collectively called corticosteroids . 1. Mineralocorticoids : (mainly Aldosterone). Regulares the mineral ( or salt) content of the blood. Their target is the kidney tubules. When aldosterone is released, Na + ions are reabsorbed and K + are released into the urine. When Na + are reabsorbed, water is reabsorbed too(osmosis). In this way, blood volume and B.P are adjusted.

65. 2 . Glucocorticoids : (corticosterone, cortisone but mainly cortisol) Maintain normal cell metabolism. Promote Protein breakdown , lipolysis and gluconeogenesis. Helps the body fight long term stressors. When glucocorticoids are released, fats and even proteins are broken down to glucose. Anti-Inflammatory : Inhibit WBC hence they slow down wound healing. Depression of Immune system : High doses can depress immune response hence they are prescribed during organ transplant.

66. 3. Sex hormones : (or Androgens) In both male and female Androgens are released but in relatively small quantities. Mainly testosterone, but some estrogen is also produced. In females after menopause, ovarian secretion of estrogen ceases and all estrogen is derived from adrenal androgens.

67. Function of Adrenal Medulla hormones 1. Epinephrine : (Adrenaline) and Norepinephrine (noradrenaline) Enhances and prolongs the effects of “ fight or flight” response of the sympathetic nervous system Increases Heart rate , B.P , Blood glucose level and dilate small passageways of the lungs. These events result in more oxygen and faster circulation of blood, mainly to brain, heart and muscles.

68. Regulation Epinephrine and norepinephrine are released when adrenal medulla is stimulated by the sympathetic nervous system during “fight or flight” response. Glucocorticoids are released from adrenal cortex in response to rising levels of ACTH in blood. Acth is secreted from the anterior pituitary lobe by the release of CRF from hypothalamus, which is controlled by steroid level in blood. Aldosterone release is stimulated by humoral factors, such as fewer Na + ions in blood. - Renin from kidneys also causes release of aldosterone when Blood pressure drops. -A hormone of heart ANP prevents aldosterone release, to reduce blood pressure.

69. Deficiency of Adrenal cortex hormones Under-secretion of all adrenal cortex hormones leads to Addison’s disease . Because of low aldosterone, Na+ and water all lost from the body, leading to: Electrolyte and water imbalance Muscle weakness Hypoglycemia Arrhythmia Lessened ability to, cope with stress. Eg.cold, which is normally easy to overcome, become life threatening.

70. Oversecretion of Adrenal cortex hormones: Hypersecretion may results from a tumor of Pituitary of Adrenal cortex. Hyperactivity of the outermost cortical area results in Hyperaldosteronism . When tumor is in the middle cortical area, Cushing’s syndrome results.Excessive glucocorticoids results in: ‘Buffalo hump’ on the upper back High blood pressure Hyperglycemia Bone weakness Severe depression of immune system.

71. Oversecretion of Adrenal Medulla hormones: Hypersecretion of epinephrine and norepinephrine leads to a prolonged “ fight or flight response” including: Sweating High Blood pressure Increased heart rate High metabolism High Glucose.

72. THYMUS GLAND Location : The thymus gland is located in the thoracic cavity, behind the sternum. Hormones : Thymosin and other hormones: Thymic humoral factor, thymic factor and Thymopoietin.

73. Function of Thymus gland: Promotes the maturation of T-cells WBCs. Other endocrine Tissues and Organs: Placenta: Human Chorionic Gonadotrophin. Estrogen and progesterone.

74. Kidney Renin -restore normal blood pressure, thereby increasing filtration rates of water and solutes in the kidney tubules. •Erythropoietin –stimulates the production of red blood cells, Calcitriol- stimulates active transport of dietary calcium across intestinal cell membranes in the intestine

75. Stomach Gastrin –stimulates glands to release hydrochloric acid. Intestine Secretin-Pancreas: stimulates release of bicarbonate-rich juice. Liver: increases release of bile. Stomach: reduces secretions and motility. •Cholecystokinin-Pancreas: stimulates release of enzyme-rich juice. Gallbladder: stimulates expulsion of stored bile. Duodenal papilla: causes sphincter to relax, allowing bile and pancreatic juice to enter duodenum.

76. Heart Atrial natriuretic peptide (ANP)-Kidney: inhibits sodium ion reabsorption and renin release. Adrenal cortex: inhibits secretion of aldosterone, thereby decreasing blood volume and blood pressure. Adipose tissues Leptin-suppresses appetite and increases energy expenditure in the brain. •Resistin-causes resistance of peripheral tissues to insulin.

77. THE END