Ch 18 - Endocrine Glands

Main regulatory functions of the endocrine system are
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Main regulatory functions of the endocrine system are
Metabolism
Control of food intake/ digestion
Tissue maturation
Ion regulation
Water balance
Heart rate, BP regulation
Control of blood glucose, other nutrients
Control or repro functions
Uterine contractions and milk release
Immune system regulation
Structure of Posterior Pituitary Gland
-Post pit is an extension of the hypothalamus and consists of the infundibulum and the neurohypophysis (secretes neuropeptides)
-Uses membrane bound receptors
-Hormones released from post pit are made by hypothalamus
Structure of Anterior Pituitary Gland
Produces nine major hormonesAnything coming from ant pit is produced there bc highly glandular
Hypothalamohypophysial Portal
Connects the hypothalamus and ant pit
-Neurohormones are produced in hypothalamic neurons
-Neurohormones inhibit or stimulate hormone production in the ant pit
(Front) - portal
Hypothalamohypophysical Tract
(Back) - nerve tract
-Connects the hypothalamus and the post pit
-Neurohormones are produced in hypothalamic neurons
and are secreted from the posterior pit
7 Hormones of the hypothalamus are
GHRH / IH
TRH
CRH
GnRH
PRH / IH
GHRH
Growth hormone - releasing
Peptide
Ant pit
GHIH
Growth hormone - inhibit /somatostatin
ant pit
TRH
Thyrotroponin- Releasing hormone
Small peptide
ant pit
CRH
Corticotroponin- releasing hormone
peptide
ant pit
GnRHGonadotroponin releasing hormone Small peptide Ant pitPRHProlactin Releasing Hormone Unknown Ant pitPIHProlactin inhibiting hormone Dopamine Ant pitHormones of the posterior pituitaryADH and oxytocinADHAntidiuretic Hormone/ Vasopressin Promotes water retention by kidneys Stimulus for release- v in blood volume, ^ blood conc Target tissue- kidneys Response- ^reabs of water, v in urine production, ^ blood volumeBaroreceptorsDetects decrease in blood volumeOsmoreceptorsDetect increase in blood osmolality/ concADH Steps of releasev blood volume ^ Blood concentration leads to release ADH to kidneys ^ in h2o reabs v in urine production ^ blood volumeAlcohol inhibits the release of which hormone?ADHOxytocinPostive feeback Stimulus for response - inc pressure on cervix, stretch of uterus Target tissues- uterus, mam glands Reponse- Uterine contractions or release of milkHormones of the ant pit-GH (somatotropin) ------- (FLAG ToP MB) -Thyroid Stimulating Hormone (TSH) -Adrenocorticotropic Hormone (ACTH) -Melanocyte stimulating hormone (MSH) -Beta Endorphins -Lipotropins -Luteinizing hormone (LH) -Follicle stimulating hormone (FSH) -ProlactinAnother name for the ant pitAdenohypophysisGH secretion increases in response toAn increase in blood amino acids, low blood glucose, or stressGH Secretion steps1) ^ AA, v glucose 2) Hypothalamus releases GHRH 3) GHRH travels ant pit via portal tract 4) Ant Pit releases GH 5) v AA, ^ glucose will signal hypothalamus to release GHIH 6) GH uses G protein with cAMPEffects of hyposecretion of GHBefore puberty: can be dwarfismEffects of hypersecretion of GHBefore puberty: Gigantism After puberty: acromegalyDoes growth hormone have a releasing hormone and/ or inhibiting hormone?BOTHTarget tissue of GH and responsesMost tissues Increased protein synthesis, tissue growth, fat breakdown, glucose synthesis, and somatomedin secretionReceptor of GHMembrane bound (protein hormone)TSH, or thyrotropin, causes the release ofthyroid hormones T3 and T4TSH Regulation Steps1) v T3, T4 2) Hypothalamus release TRH 3) TRH travels to ant pit via portal tract 4) Ant pit releases TSH to thyroid hormone 5) ^ T3, T4 will signal hypothalamus toWhich 2 hormones have an inhibiting hormone?GH and prolactinTarget Tissues of TSH and responseThyroid gland Release of thyroid hormones T3 and T4Receptors of TSHMembrane bound (G protein cAMP)ACTH, MSH, endorphins and lipotropins all derived from the same large precursor molecule _______Proopiomelanocortin when stimulated by CRHTSH releasing HormoneTRHIf it says releasing or inhibiting that means it comes from?HypothalamusACTH stimulates cortisol secretion from the _________ and _________ skin pigmentationadrenal cortex and increases skin pigmentationRegulation of ACTH Secretion Steps1) v cortisol 2) Hypothalamus releases CRH 3) CRH travels via portal tract to ant pit 4) Ant pit releases ACTH to adrenal cortex 5) ^ cortisol will signal hypothalamus toACTH releasing hormoneCRHACTH target tissues and responseAdrenal cortex Causes cortisol and aldosterone secretion, binds directly to melanocytes of the skin; causes increase in production of melaninACTH ReceptorsMembrane bound (g protein cAMP)Lipotropins causeFat BreakdownBeta endorphins play a role in ________, they're released during ______________analgesia stressMSH increasesSkin pigmentationGonadotropinsGlycoprotein hormones that promote growth and function of the gonads (LH, FSH, and prolactin)LHLeutinizing HormoneLeutinizing Hormone Releasing HormoneGnRHLeutinizing Hormone target tissuesOvaries/ testes Regulates production of gametes and repro hormones OvulationFSHFollicle stimulating hormoneFSH Releasing hormoneGnRHFSH target tissuesFollicles in ovaries or seminiferous tubules in testes, Regulates production of gametes and reproductive hormonesTestosteroneSperm productionEstrogen and progesteroneFollicle MaturationProlactin Releasing hormone and receptorsPRH Membrane boundProlactin target tissuesOvaries and mammary glands in femalse, Milk productionThyroid Gland is locatedto the larynxThyroid Gland HistologyComposed of follicles: follicular cells surrounding thyroglobulin/ thyroid hormones -Parafollicular cells: between follicles secrete calcitoninWhere does T3 and T4 occursThyroid folliclesT3 and T4 Synthesis1) Active transport of Iodide into follicular cells 2) Thyroglobulin synthesized in follicular cells from Tyrosine 3) Thryoglobulin is secreted into follicular lumen by exocytosis 4) Two Iodinated tyrosine amino acids of thyroglobulin join to form T3/4 5) T3 and T4 are stored in the follicular lumen 6) stimulation of thyroid gland by TSH leads to endocytosis of thryoglobulin into follicle cells 7) Enzymes breakdown thyroglobulin releasing T3 & T4 8) T3/4 are transported in blood with TBGGoiterLow iodide in diet, low T3/4 > hypothalamus keeps releasing TRH, TSH, no T3/4 > enlarge thyroid glandWhich form is the most active and usuable T3 or T4?T3TRH increases as a result ofchronic exposure to cold, food deprivation, and stressTRH from the hypothalamus increases ________ secretionIncreased TSH from the anterior pituitary increasesT3 and T4 secretionT3 and T4 affectnearly every tissue in the bodyT3 and T4 increase the rate ofglucose, fat, and protein metabolism in many tissues, thus increasing body temperature.Normal growth of many tissues is dependent onT3 and T4T3 and T4 bind with ______________ to initiate new protein synthesisNuclear receptor moleculesT3 and T4 inhibitTSH and TRH secretionWhat are the affects of hypersecretion of the thyroid hormone?Weight loss, increased appetite, increased metabolic rate, increased heart rate and blood pressureCalcitonin is produced byParafollicular cellsSecretion of calcitonin is triggered byHigh Ca+ concentration in bloodCalcitonin decreases Ca+ concentration byinhibiting osteoclast activityWhat is the primary target tissue of calcitonin?Bone. Decreases osteoclast activity, lengthens the life span of osteoblastsWhat stimulates PTH secretion?A decrease in blood calciumPTH increases blood calcium levels bycalcium reabs in the kidneys and the formation of active vitamin D by the kidneys. Active vitamin D increases calcium absorption by the intestine.What are the effects of hyposecretion of PTH?Decreased Ca+The adrenal glands are nearThe superior poles of the kidneysThe adrenal medulle is composed ofClosely packed cellsWhat are the 3 layers of the adrenal cortex?Zona glomerulosa Zona fasciculata Zona reticularisWhat do the hormones of the adrenal medulla do?Prepare the body for physical activityHormones of the adrenal medulla are stimulated by _____________ in response to ____________The sympathetic division in response to emotions, injury, stress, exercise, and low blood glucose levelsWhat 2 hormones does the adrenal medulla mostly account for?Epinephrine (80%) Noepinephrine (20%)What are the effects of E and NE^ release of glucose from liver ^ fat release ^ heart rate, BP ^ constriction of BV in skin, vasodilation in muscle DECREASED digestive functionsThe zona glomerulosa secretesmineralocorticoids, specifically aldosteroneAldosterone acts onKidneys to increase blood level of sodium by increasing sodium reabs Decrease blood levels of P and H levels by increasing K+ and H+ ion secretionReabsorption istubule >> bloodSecretionblood >> tubuleHypersecretion of Aldosterone^ Na+ in blood, H20, BV, BP, K+ secretion, K+ in urine v K+ in bloodAldosterone^ Na+ reabs, Na+ in blood, v Na+ in urineZona Fasciculata SecretesGlucocorticoids, specifically cortisolAddisons DiseaseHyposecretion of glucocorticoids by the adrenal cortex ^ ACTH, ^ MSH Causes bronzing of skinCrushing SyndromeHpersecretion of glucocorticoids by adrenal cortex Weight gain in the trunk of the body, not limbsWhat are the effects of cortisol?^ fat and protein breakdown ^ glucose synthesis from amino acids v the inflammatory responseSteps to release cortisolv blood sugar, stres CRH secreted from hypothalamus Stimulates the ant pit to release ACTH Targets the zona fasciculate causing release of cortisolZona Reticularis secretesAndrogens (converts to testosterone by peripheral tissues) In females, androgens stimulate axillary and pubic hair growth and sex driveOnce cortisol levels are optimal it inhibitsCRH and ACTHThe pancreas is locatedAlong the small intestine and the stomach (retropertoneal) Both an exocrine and an endocrine gland (only one!)Exocrine portion of pancreasacini cells - digestive enzymesWhat do acini produce?Pancreatic digestive juicesEndocrine portion of the pancreasConsists of pancreatic isletsEach pancreatic islet is composed ofAlpha cells, secrete glucagon Beta cells, secrete insulin Delta cells, secrete somatostatinInsulin's target tissuesLiver, adipose tissue, muscle, and the satiety center in the hypothalamusGlucagons target tissueThe liverGlucagon causes thebreakdown of glycogen and fats for use as an energy sourceInsulin increases theuptake of glucose and amino acids by cells Glucose is used for energy or is stored as glycogen AA are used for energy or are converted to glucose or proteinsInsulin secretion increases because ofElevated blood glucose levels An increase in some AA, Parasympathetic stimulation, and gastrointestinal hormones. Sympathetic stimulation decreases insulin secretionHow does sympathetic stimulation affect insulin secretion?Decreases itGlucagon secretion is stimulated byLow blood glucose levels, certain AA, and sympathetic stimulationSomatostatin inhibitsINsulin and glucagon secretionImmediately after a meal, the following events take placeHigh glucose levels inhibit glucagon, cortisol, GH, and E. Insulin secretion increases, thereby increasing the uptake of glucose, AA, and fats, which are used for energy or storedMany hours after a mealBlood glucose levels decrease Glucagon, GH, cortisol, and E levels increase Insulin levels decrease, glucose is released from tissues Adipose tissue releases fatty acids, triglycerides, and ketones, which most tissues use for energyShort Term ExerciseIncreased sympathetic stimulation Increased E and glucagon Decreased insulin Glycogen is broken down,glucose released Increased breakdown of FatProlonged ExerciseACTH, cortisol, and GH released Increased protein breakdown in a muscle Increased breakdown of fatWhat secretes repro hormones?Ovaries, testes, placenta, and pit glandMale repro hormonesTestosterone InhibinTestosteroneReleased from intersitial cells of testes Targets most cells Response: secondary sexual characteristics and sperm production in seminiferous tubulesInhibin (male)Released from sertoli cells of testes Target: ant pit Response: inhibit release of FSHFemale Repro HormonesEstrogen Progesterone inhibin RelaxinEstrogenReleased from ovaries Target: most cells Response: secondary sexual characteristicsProgesteroneReleased from corpus luteum in ovaries Target: Uterus Reponse: prepares uterus for implantationInhibin (female)Released from ovaries Target: ant pit Response: increase flexiblity of connective tissue in pelvisMelatoninReleased from pineal gland Target: hypothalamus Reponse: inhibits GnRH Inhibition of melatonin: light rays Causes sleep, can cause depressionThe thymus producesThymosin which targest the immune tissue (lymphocytes)The heart releasesAtrial Natriuretic Peptide which targets the kidneys and BV and helps to regulate fluid volume and blood pressureThe kidneys releaseErythropoietin which targets the bone marrow and results in RBC production