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Human Physiology H4b
Handout 4 Part 2 intro to Endocrine System
| Question | Answer |
|---|---|
| What is a hormone? | SECRETED by a specific cell or grp of cells, TRANSPORTED by the BLOOD, BIND to recpetors on the TARGET cell, exerts effects at VERY LOW CONC., and ACTION must be TERMINATED |
| Endocrine glands | specialized in secretion; endocrin or exocrine; PRIMARY endocrine organs and SECONDARY endocrine organs |
| Endocrine | secrete into blood |
| Exocrine | secrete outside the body via a duct includes lumen of small intest adn stomach |
| Primary endocrine organs | primary function is the SECRETION OF HORMONES |
| Secondary endocrine organs | is secondary to some other function; not a major fun Ex. in the heart and kidney things are secreted but its not their major function |
| Hypothalamus and Pituitary gland | Major control system for the Endocrine System; together they regulate alomst every body system |
| Infundibulum | Thin stalk of tissue that connects the hypothalamus to the pit gland |
| Hypothalamus | has endorine AND nonendocrine functions, CONTROLS the Pit gland |
| Pituitary Gland | has two portions; Anterior pituitary and posterier pituitary |
| Anterior pituitary (adenohypophysis) | a true endocrine gland,originates from epithelial tissue; PRODUCES, STORES and RELEASES 6 homrones as needed; none are steriods b/c is hydrophilic; all secretion controlled by HYPOTHALAMIC NEUROHORMONES and trophic hormones |
| Posterior Pituitary (neurohypophysis) | originates form the brain-neural tisssue; cell body in hypothalamus and axon thru infundibulum, stores and directly releases 2 neurohormones: VASOPRESSIN and OXYTOCIN |
| Vasopressin | (ADH): anti-diaretic hormone, regs kidney funx |
| Oxytocin | uterine contractions adn lactation in breastfeeding |
| Structural class of anterior and posterior pituitary gland | Protein/peptides, unless you know otherwise IT"S ALWAYS PROTEIN/PEPTIDE |
| Hypotholamic Neurhormones | hypothalmic controls anterior pit. gland by releasing or inhibiting hormones;RELEASING hormones-activating release of anterior pit gland hormone OR INHIBITING hormones-blocking the release of anterior pituitary gland hormones |
| trophic (tropic) hormone | a hormone that controls the release of another hormone |
| Hypothalamic-hypophyseal portal system | Hormones may have a multi step pattern of responses. hypothalamus controls the anterior pituitary gland which controls the adrenla gland and those hormones releasing another after that; |
| the portal system in the liver | 2 cap beds in series connected by a portal vein goes to an organ going to a second cap bed then going to the heart |
| the hepatic portal system | all blood goes thru the liver before going tho the heart |
| the portal system btwn hypothalamus and anterior pituitary gland | 1st cap bed in hypothalamus releases hormone onto caps,collect into portal vein and collect in 2nd cap bed of ant. pit gland. All extremely small in volume b/c tiny # of neurons in hypothalamus releasing the inhibtry hormones,releasing hypotrophic hormone |
| Low conc. of hormone in cap beds | b/c to low for blodd, so seperated in small conc to produce a response in anterior pit. gland |
| Rough overview of portal system | Hypothalamic hormones released into the pr=ortal system initiate the release of anterior pituitary gland hormones acting on endocrine and nonendocrine target hormones to produce a response |
| Feedback loops in te hypothalamic-pituitary pthwy | Multiple levels of control equals significant delay. Each hormone acts as a negative feedback SIGNAL, instead of the response functioning as the negative feedback |
| Each hormone acts as a negative feedback SIGNAL | long-loop feedback and Short-loop feedback; Both regulate feedback; usually it alters places where we have tripic hormone production but because of delay, the hormonal releases itself |
| Long-loop feedback | refers to diff type of control specifications for the hypothalamic pit relation |
| Short-loop feedback | how close anterior pit. gland is to hypothalamus; negative FB of hypothalamus |
| Primary Endocrine Glands (7) | Pineal gland, thyroid gland, Parathyroid gland Thymus, Adrenal glands, Pancreas, and Gonads |
| Pineal gland | regulates sleep cycles; releases melatoinin |
| Thyroid gland | Increases cell metabolism; release thyroid hormones T3 and T4 and calcitonin |
| Goiter of thyroid gland | enlargement in the thyroid |
| Parathyroid Glands | calcium homeostasis; releases parathyroid hormone |
| Thymus | T cell regulation adn immune response; releases thymosin |
| Adrenal glands | 2 parts adrenal cortex and adrenal medualls; both functions as endocrine activity, adrenaline and NorE |
| Adrenal cortex | outside part; releases mineralcorticoids, glucorticoids and androgens |
| Adrenal medullas | originates from the nervous system; releases chromaffin cells secrete epinephrine and NorE |
| Pancreas | involoved in glucose levels of blood; release insulin, glucagon and somatostatin |
| Gonads | organ producing sex cells releasing sex hormones; release testosterone and androstenedione in males; release estradiol and progesterone in females |
| Secondary Endocrine Organs | Heart, Liver, Kidney, GI tract and Skin |
| Heart | releases Atrial Natriuretic Peptide (ANP) released by cells in the R atria involved in BP control |
| Liver | involved in growth; releases insulin-like growth factor (IGF) controlled by growth hormone |
| Kidney | releases erythopoietin wich stimulates RBC invoved in BP control |
| GI tract | involved in digestive activity releases gastrin ,CCK, secreetin, glucose-dependent insulinotropic peptide (GIP) all produced by small intestine except gastrin |
| Skin | releases vitamin D produced by the skin |
| Hormone actions at target cell | Must know how a specific target cell will respond;Actions depend on 3 things: type pf receptor, signal transduction mechanisms and hormone concentration |
| Hormone concentration | rate of hormone secretion, hormone transport to bound receptors and hormone metabolism |
| Hormone transport to boound receptors | transportationmethod bound to receptor or not |
| Hormone metabolism | degradation, some in blood, some in blood directly as pass thru level or by enzymes individual cells have |
| Hormone secretion: humoral and neural control | Humoral control seperate from hypothalamus Explains concept of control; and pit gland so sometimes neg feedback response loop. |
| Humoral Control | Body fluid; like blood; Humoral response is reated to cells in the pancreas responding to glucose levels in the blood, changing blood glucose levels producing an efferent pathwy hormone that has target responses in a neg FB response loop. |
| hORMONES mUST bE stopped | Hormones in the blood are degraded, lipophobic hormones bound to membrane receptors and lipophilic hormones degrades by cystolic/nuclear enzymes (like steroids). |
| degradation of hormones | produce inactive metabolites, half life is influences by mode of travel and hormones bound to carrier proteins have much longer half life |
| Lipophobic hormones bound to MEMBRANE receptors | hormones die via endocytosis, digestion by lysosomes |
| Hormone interactions | synergism, permissiveness and antagonism |
| Synergism | sum of 2 things acting at same time is greater than adding them individually Ex. Epinephrine & Glucagon, alone they increase glucose levels in the blood 15%, together they increase glucose levels in the blood 22%. Together they increases eachothers effect |
| Permissiveness | 2 hormones, 1 does everything and 1 does nothing alone but its presence aids the other to do better, allowing other one to funx optimally. ex. estrogen and testosterone. W thyroid and rep. hormones get normal rate of rep hormone so thyroid is permissive w |
| Antagonism | 2 hormones that have opposite effects in normal homeostasis Ex. parathyroid hormone and Calcitonin, Insulin and Glucagon used clinically to alter drugs in clinical pharmacology and have opposite actions on glucose in the blood |
Created by:
Lkellyfly
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