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Endocrine Glands

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 . Endocrine Glands. Hormonal Communication. Hypothalamus. Part of brain

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Endocrine Glands

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  1. Endocrine Glands

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

  3. Hypothalamus • Part of brain • Regulates ANS, emotions, feeding/satiety, thirst, body temperature, etc. • Hormones related to these functions • “Releasing hormones” • Axonal transport to posterior lobe

  4. Anterior Pituitary • “Releasing” hormones regulate AP aka adeno hypo physis“glands”“under” “growth” • All proteins • TSH (thryoid stimulating hormone/thyrotropin) • ACTH (adrenocorticotropic hormone) • FSH (gonadotropin) • LH (gonadotropin) • Tropins/tropic hormones • GH (growth hormone) • Prolactin-releasing H Hypothalamic Pituitary Axis Animation : IP Web

  5. Anterior Pituitary

  6. Anterior P. Homeostatic Imbalances Growth hormone (GH or hGH) • Promotes mitosis, cell division • Elongation of long bones, etc. • Healing of wounds Lack of hGH retards growth • Hypersecretion in youth produces giantism • Hyposecretion in childhood produces pituitary dwarfism • Hypersecretion in adult produces acromegaly

  7. Posterior Pituitary • Axonal transport to Posterior Pituitary aka neuro hypo physis “nerve”“under” “growth” • Hypothalamic cell bodies synthesize • oxytocin • ADH

  8. Pituitary—Posterior lobe • Oxytocin • Stimulates smooth muscle contraction of uterus & mammary glands. • Antidiuretic H. • Stimulates water reabsorption in collecting ducts. • Stimulates vasoconstriction (vasopressin) • Lack  diabetes insipidus

  9. Posterior Pituitary Homeostatic Imbalances ADH • Hyposecretion produces diabetes insipidus “tasteless” • Excessive thirst and urination • central or neurogenic DI • gestagenic orgestational DI • nephrogenic DI • dipsogenic DI Diabetes Insipidus Foundation, Inc.

  10. Thyroid Gland • Location in neck • Inferior to larynx • Anterior & lateral to trachea • Composed of follicles • Follicle cells produce thyroglobulin • Thyroxin (T4) • Triiodothyronine (T3) • Both “thyroid hormone”, body’s major metabolic hormone • Parafollicular/ C cells • Calcitonin • Decreases blood Ca2+ by depositing it in bones

  11. Homeostatic imbalances • Hypothyroidism results • Myxedema (in adults) • Goiter—low levels of iodine • Cretinism (in children) • Hyperthyroidism results • Graves disease

  12. Parathyroid Glands • Four small glands embedded in posterior of thyroid • Parathyroid hormone (PTH) • Stimulates osteoclasts to free Ca2+ from bone • Stimulates Ca2+ uptake from intestine & kindey Hormonal Regulation of Calcium

  13. Parathyroid Homeostatic Imbalances • Severe hyperparathyroidism causes massive bone destruction • If blood Ca2+ fall too low, neurons become overactive, resulting in tetany

  14. Feedback Loop • Negative feedback in calcium homeostasis. A rise in blood Ca2+ causes release of calcitonin from the thyroid gland, promoting Ca2+ deposition in bone and reducing reabsorption in kidneys. • A drop in blood Ca2+ causes the parathyroid gland to produce parathyroid hormone (PTH), stimulating the release of Ca2+ from bone. • PTH also promotes reabsorption of Ca2+ in kidneys and uptake of Ca2+ in intestines.

  15. Adrenal Glands One on top of each kidney • Cortex • Corticosteroid • glandular • Medulla • Catecholamines • neurohormonal • Epinephrine • Norepinephrine

  16. Adrenal Cortex • Cortex • Activity stimulated by ACTH • Controls prolonged responses by secreting corticosteroids. • Mineralcorticoids • Aldosterone regulate salt and water balance • Glucocorticoids • Cortisol regulate glucose metabolism and the immune system. • Gonadocorticoids • Androgens • Estrogens

  17. Adrenal Cortex Imbalances • Hypersecretion leads to Cushing’s disease • ACTH-releasing tumors or side effects of corticoid drugs. • Hyposecretion leads to Addison’s Disease • Deficits in glucocorticoids and mineralcorticoids

  18. Adrenal Medulla • Medulla • The adrenal medulla mediates short–term responses by secreting catecholamine hormones. • Cells are modified neurons (lack axons) • Epinephrine (adrenaline) • Norepinephrine (noreadrenaline) • enable a rapid ( fight-or-flight ) responses to stress by increasing blood glucose and blood pressure and directing blood to the heart, brain, and skeletal muscles.

  19. Pancreas • Consists of two major types of secretory tissues which reflects its dual function • Exocrine gland • secretes digestive juice • localized in the acinar cells • Endocrine gland • releases hormones • localized in the islet cells (islets of Langerhans)

  20. Pancreatic Islets • “About a million” embedded in pancreas • Control centers for blood glucose • Insulin from beta cells • Glucagon from alpha cells

  21. Insulin Glucagon

  22. Islets of Langerhans • Insulin stimulates glucose uptake, glycogenesis • Glucagon stimulates glycogenolysis, glucose release from liver (vs gluconeogenesis)

  23. Feedback Loop • A rise in blood glucose causes release of insulin from beta cells the pancreas, promoting glucose uptake in cells and storage as glycogen in the liver. • A fall in blood glucose stimulates alpha cells in the pancreas to secrete glucagon, which causes the liver to break down glycogen and release glucose.

  24. Pancreas Homeostatic ImbalancesDiabetes “siphon” mellitus mel= “honey” • Symptoms: • Polyuria • Polydipsia • Polyphagia Blood Level Regulation in Diabetics

  25. Gonads • Ovaries • Estrogens • Progesterone • Testes • Testosterone • Reproductive functions when we study reproductive system.

  26. Pineal gland • Melatonin • ? Inhibits early puberty • ? Day/night cycles • Timing of sleep, body temperature, appetite • Secretes melatonin during darkness • Participates in setting the body’s clock • Melatonin is a potent antioxidant • Melatonin is high when young and is reduced as we age

  27. Thymus • Thymus gland • Thymopoietins, thymic factor, thymosins • Influence development of T lymphocytes

  28. Non-Endocrine Gland Hormones • Stomach (gastrin) • Small intestine (duodenumintesetinal gastrin, secretin, cholecystokinin) • Heart (atrial natriuretic peptide) • Kidneys (erythropoietin, active vitamin D3) • Adipose tissue (leptid, resistin) • Skin • Placenta (human chorionic gonadotropin, human placental lactogen, relaxin)

  29. Functions regulated by the Endocrine System Growth Healing Water balance & Blood Pressure Calcium Metabolism Energy Metabolism Stress Regulation of other Endocrine Organs

  30. Growth Growth hormone-releasing hormone Human growth hormone (hGH) Thyrotropin (TSH) Thyroxine & triiodothyronine Calcitonin Somatostatin (GHIH)

  31. Healing Growth hormone-releasing hormone Human growth hormone (hGH) Thyrotropin (TSH) Thyroxine & triiodothyronine Calcitonin Glucagon, Insulin Erythropoietin

  32. Water balance & Blood pressure ADH Aldosterone Angiotensin II Atrial natriuretic H. Epinephrine

  33. Calcium Metabolism Calcitonin Parathyroid H. (PTH) Estrogens/androgens Growth hormone

  34. Energy Metabolism Thyroxine & triiodothyronine Thyroid-stimulating H. (thyrotropin, TSH) Epinephrine & norepinephrine Insulin Glucagon Adrenocorticotropic H. (ACTH) Cortisol

  35. Stress Epinephrine & norepinephrine T4 &T3 ?? ACTH Cortisol

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