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22 Cards in this Set
- Front
- Back
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cells of the pituitary gland secreting which hormones are acidophils? basophils?
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acidophils - GH, prolactin
basophils - rest FLAT PiG (FSH, LH, ACTH, TSH, ProlacIn, GH) |
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FSH shares a subunit with other hormones, which hormones? which subunit is shared and which is unique?
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TSH, LH, FSH, hCG all share alpha subunit
beta subunit determines hormone specificity *remember this because pregnancy test is BETA-hCG |
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what stimulates insulin release from beta cells? what inhibits it?
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epinephrine/glucagon --> increased cAMP --> increased intracellular Ca++ --> inuslin released
High glucose (from GLUT2) --> high ATP/ADP ratio --> increased activity of ATP sensitive K+ channel --> depolarization --> increased Ca++ influx --> insulin release *inhibited by alpha-2 receptor agonization, or by low ATP/ADP |
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varies GLUT transporters, activities, and tissues?
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GLUT1 - insulin independent; brain, RBCs
GLUT2 - bidirectional, insulin independent; beta-islet cels, liver, kidney, small intestine GLUT4 - insulin RESPONSIVE, adipose tissue, skeletal mm Qbank: GLUT3 - placenta, brain, kidney GLUT5 - spermatocytes, GI tract (fructose transport) |
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which tissues are insulin dependent?
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adipose tissue, skeletal mm
GLUT4 |
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What is the effect of glucagon? how is it stimulated? inhibited?
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glycogenolysis & gluconeogenesis
lipolysis & ketone production stimulated by hypoglycemia inhibited by insulin, hyperglycemia, & somatostatin |
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Hypothalamic-pituitary hormone regulation:
TRH --> Dopamine --> CRH --> GHRH --> Somatostatin --> GnRH --> Prolactin --> |
TRH --> + TSH, prolactin
Dopamine --> - prolactin CRH --> + ACTH GHRH --> + GH Somatostatin --> - GH, TSH GnRH --> + LH, FSH Prolactin --> - GnRH |
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what is the fxn of prolactin? how is it stimulated? inhibited?
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prolactin stimulates milk production; inhibits ovulation (& spermatogenesis) by inhibiting GnRH
Stimulated by TRH (or disinhibition of dopamine) Tonically inhibited by dopamine; feeds back and inhibits self Dopamine agonists (bromocriptine) inhibit prolactin secretion - tx prolactinoma Dopamine antagonists (antipsychotics) & estrogens (OCP, pregnancy) stimulate prolactin secretion |
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what is the fxn of GH? how is it regulated?
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stimulates linear growth & mm (thru somatomedin secretion)
increases insulin resistance (diabetogenic) GHRH stimulates GH release; pulsatile secretion increases during exercise & sleep secretion is inhibited by glucose & somatostatin |
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what are the fxns of cortisol? how does it circulate?
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binds to CBG (corticosteroid-binding globulin)
Cortisol is BBIIG 1.) maintains Blood pressure (upregulates alpha-1 receptors) 2.) decreases Bone formation 3.) anti-Inflammatory/Immunosuppressive ---inhibits production of leukotrienes & prostaglandins --inhibites leukocyte adhesion --> neutrophilia --blocks histamine release from mast cells --reduces eosinophils --blocks IL-2 production 4.) increases Insulin resistance (diabetogenic) 5.) increases Gluconeogenesis, lipolysis, proteolysis |
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where is PTH produced? what are its functions?
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produced by Chief cells of the parathyroid; increases Ca+ & decreases PO4
1.) increase bone resorption of Ca++ & PO4 2.) increase renal absorption of Ca++ (distal tubule) 3.) decrease renal absorption of phosphate 4.) increase kidney activity of 1alpha-hydroxylase, increasing 1,25-OH vitamin D (calcitriol) |
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how does PTH increase bone resorption?
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stimulates osteoblasts, which secrete M-CSF & RANK-L, which stimulate osteoclasts
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how is PTH regulated?
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PTH secretion is increased w/low free Ca++ and Mg++
low Mg++ caused by: diarrhea, aminoglycosides, diuretics, alcohol abuse |
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what does vitamin D deficiency cause in adults? kids?
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adults - osteomalacia
kids - rickets |
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how is Vitamin D production stimulated? inhibited?
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1alpha hydroxylase is stimulated by - high PTH, low Ca and phosphate, produces more active vitamin D
1,25-OH vitamin D feedback inhibits its own production |
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where is calcitonin produced? what does it do?
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parafollicular cells (C cells) of thyroid
it decreases bone resorption of calcium; it is secrted in response to high Ca (in medullary carcinoma might see high primary calcitonin levels --> hypocalcemia w/trousseaus and chvotsek's sign) |
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what does increased/decreased SHBG do?
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in men, increased SHBG --> lowers free testosterone --> gynecomastia
in women, decreased SHBG --> raises free testosterone --> hirsuitism |
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which thyroid hormone is the active form? what are the funcitons?
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T3 is active; majority is formed by peripheral conversion (5' deiodinase); binds to steroid transcription factors in the nucleus
Fxns - 4B's, Brain, Bone, Beta-adre, BMR 1.) Bone growth (synergism w/GH) 2.) CNS maturation 3.) increased beta-receptors in heart 4.) increased basal metabolic rate (via increased Na/K ATPase activity) 5.) increase glycogenolysis, gluconeogenesis, lipolysis |
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how is thyroid hormone regulated?
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TRH stimulates TSH, stimulating follicular cells
negative feedback of T3 to anterior pituitary decreases sensitivity to TRH |
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what is Wolff-Chaikoff effect?
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excess iodine inhibits thyroid peroxidase, which prevents organification
lasts ~10 days before "escape phenomenon" |
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how does thyroid hormone circulate? what effects this?
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bound to TBG
TBG decreases w/hepatic failure TBG increases w/pregnancy or OCP use |
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what enzymes are important for thyroid hormone to be active? how are the manipulated pharmacologically?
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5'-deiodinase converts T4 to T3 in the periphery
Peroxidase is responsible for oxidation & organification of iodide, and coupling of MIT & DIT Propylthiouracil inhibits peroxidase & 5'-deiodinase Methimazole inhibits peroxidase |