Hormones
ESSENTIAL INFORMATION ABOUT HORMONES __________________________________________________________________________________________________________________________________ NAME: growth hormone, GH, somatotropin SOURCE: anterior pituitary gland TARGET CELL(S): all cells of the body PRINCIPAL EFFECT(S): increased protein anabolism, increased lipolysis, increased glycogenolysis net result = increased blood glucose back to normoglycemia CONTROL OF SECRETION: hypothalamic releasing factor secreted in response to hypoglycemia; hypothalamic inhibiting factor secreted in response to hyperglycemia __________________________________________________________________________________________________________________________________ NAME: thyroid stimulating hormone, TSH, thyrotropin SOURCE: anterior pituitary gland TARGET CELL(S): follicle cells of the thyroid gland PRINCIPAL EFFECT(S): increased thyroxine (T3 and T4) secretion from the thyroid gland; as a result of thyroxine, basal metabolic rate increases CONTROL OF SECRETION: decreased basal metabolic rate stimulates TSH-RF from hypothalamus; increased basal metabolic rate turns off TSH-RF secretion __________________________________________________________________________________________________________________________________ NAME: adrenocorticotropic hormone, ACTH SOURCE: anterior pituitary gland TARGET CELL(S): zona fasciculata cells of the adrenal cortex PRINCIPAL EFFECT(S): increased glucocorticoid (hydrocortisone, cortisone, cortisol) secretion from the adrenal cortex; as a result of glucocorticoids, stress is reduced CONTROL OF SECRETION: increased stress stimulates secretion of hypothalamic corticotropin-RF (C-RF); decreased stress turns off C-RF secretion __________________________________________________________________________________________________________________________________ NAME: follicle stimulating hormone, FSH SOURCE: anterior pituitary gland TARGET CELL(S): male -- spermatogonia and Sertoli cells of the testes female -- primordial follicles of the ovaries PRINCIPAL EFFECT(S): male -- directly stimulates sperm formation and secretion of the hormone inhibin female -- directly stimulates egg production and in doing so stimulates estrogen secretion CONTROL OF SECRETION: male -- hypothalamic gonadotropin-RF (Gn-RF) released in response to decreased inhibin female -- hypothalamic Gn-RF secreted in response to decreased estrogen __________________________________________________________________________________________________________________________________ NAME: luteinizing hormone, LH (in the male sometimes known as interstitial cell stimulating hormone (ICSH) SOURCE: anterior pituitary gland TARGET CELL(S): male -- Leydig cells (interstitial endocrinocytes) of the testes female -- tertiary follicle and ovary PRINCIPAL EFFECT(S): male -- stimulates Leydig cells of testes to secrete testosterone female -- directly stimulates ovulation, which leads to formation of a temporary endocrine organ known as the corpus luteum CONTROL OF SECRETION: male -- hypothalamic Gn-RF secreted in response to decreased testosterone female -- hypothalamic Gn-RF secreted in response to increased estrogen __________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________ NAME: prolactin, PRL SOURCE: anterior pituitary gland TARGET CELL(S): male -- unknown female -- mammary gland cells PRINCIPAL EFFECT(S): male -- unknown female -- increased milk synthesis (not secretion) by postpartum mammary glands CONTROL OF SECRETION: PRL-IF secreted by hypothalamus in response to increased estrogen PRL-RF secreted by hypothalamus in response to decreased estrogen after pregnancy and via a neuroendocrine reflex initiated by sucking of postpartum nipple __________________________________________________________________________________________________________________________________ NAME: melanocyte stimulating hormone, MSH SOURCE: anterior pituitary gland TARGET CELL(S): melanocytes of skin PRINCIPAL EFFECT(S): increased skin pigmentation by stimulation of melanocytes CONTROL OF SECRETION: MSH-RF and MSH-IF secreted from hypothalamus; mostly not understood __________________________________________________________________________________________________________________________________ NAME: antidiuretic hormone, vasopressin, ADH SOURCE: hypothalamic neurons via the posterior pituitary gland TARGET CELL(S): distal tubule and collecting duct cells of the kidneys PRINCIPAL EFFECT(S): increased permeability of kidney tubule cells to water, allowing increased water conservation from forming urine CONTROL OF SECRETION: increased extracellular osmolarity within the hypothalamus stimulates action potentials in the hormone-forming cells, causing release of the hormone; when extracellular osmolarity falls back within normal range, ADH secretion ends __________________________________________________________________________________________________________________________________ NAME: oxytocin, OT SOURCE: hypothalamic neurons via the posterior pituitary gland TARGET CELL(S): male -- unknown female -- uterine smooth muscle, myoepithelial cells of mammary glands PRINCIPAL EFFECT(S): male -- unknown female -- stimulates contraction of uterine smooth muscle during labor; stimulates contraction of myoepithelial cells in mammary glands causing milk secretion (letdown) CONTROL OF SECRETION: increased stretch of pregnant cervix and tactile stimulation of postpartum areola and nipple __________________________________________________________________________________________________________________________________ NAME: thyroxine, tetraiodothyronine (T4), triiodothyronine (T3) SOURCE: thyroid gland follicles TARGET CELL(S): all cells of the body PRINCIPAL EFFECT(S): increased carbohydrate catabolism, increased fat catabolism, increased protein anabolism; net effect is increased basal metabolic rate of body CONTROL OF SECRETION: hypothalamic TSH-RF secreted in response to decreased basal metabolic rate, causing secretion of TSH from anterior pituitary gland, which in turn stimulates thyroid follicle cells to release thyroxine __________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________ NAME: calcitonin, CT SOURCE: parafollicular cells (C cells) of the thyroid gland TARGET CELL(S): osteoblasts of bone, kidney tubule cell PRINCIPAL EFFECT(S): increased bone formation and ossification; prevent calcium reabsorption by kidneys CONTROL OF SECRETION: hypercalcemia (too much calcium in blood) directly stimulates parafollicular cells to secrete CT; when blood falls back into normocalcemic range, CT secretion stops __________________________________________________________________________________________________________________________________ NAME: parathyroid hormone, PTH, parathormone SOURCE: chief cells of the parathyroid glands TARGET CELL(S): osteoblasts, kidney tubule cells, intestinal cells (in conjunction with vitamin D) PRINCIPAL EFFECT(S): increase bone resorption, increased calcium reabsorption by kidneys, increased intestinal of dietary calcium CONTROL OF SECRETION: hypocalcemia (too little calcium in blood) directly stimulates chief cells to secrete PTH; when calcium rises back into normocalcemia range, PTH secretion stops __________________________________________________________________________________________________________________________________ NAME: aldosterone (a mineralocorticoid) SOURCE: zona glomerulosa cells of adrenal cortex TARGET CELL(S): kidney tubule cells PRINCIPAL EFFECT(S): increased sodium reabsorption with concomitant water reabsorption by osmosis, coupled with increased potassium secretion into the forming urine CONTROL OF SECRETION: 2 mechanisms: (1) increased potassium in extracellular fluid stimulates aldosterone secretion, leading to loss of potassium from body (2) renin-angiotensin pathway, which is activated any time there is a decrease in blood pressure __________________________________________________________________________________________________________________________________ NAME: hydrocortisone, cortisol, cortisone (all 3 are different glucocorticoids) SOURCE: zona fasciculate of adrenal cortex TARGET CELL(S): all cells of the body PRINCIPAL EFFECT(S): 1.