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33 Cards in this Set
- Front
- Back
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hypothalamus acts as how |
connection between brain and endocrine system integrating signals like temp, thirst/hunger, light, immune responses to infection |
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where is the BB barrier missing in brain? why |
some areas around the hypothalamus so brain can directly communicate with hormones in the blood example: GH negative feedback |
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where are hypothalamic hormones secreted to? pattern of release? |
anterior pit: via hypophysial vessel posterior pit: neurons starting in hypothalamus project to/ terminate in post pit pulsatile release |
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outputs of hyp |
1. direct innervation of adrenal medulla / other endocrine tissues 2. neurosecretion: hormone secreted by hypothalamic nuclei and act on pituitary |
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TRH // function |
thyrotropin releasing hormone regulation of TSH - thyroid stim hormone |
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GnRH // function |
gonadotropin releasing hormone regulation of gonadotropins FSH (follicle stim hormone) and LH (leutinizing hormone) |
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somatostatin function |
inhib glucagon, insulin, GH, TSH, and others (-) regulator |
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GHRH // function |
growth hormone releasing hormone tropic effect on GH (stim it) trophic for somatotrophs - cause them to grow/thrive |
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PIH // function |
prolactin inhibiting hormone (same as DA) inhibits PRL (prolactin release) |
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CRH |
corticotropin releasing hormone regulates ACTH, appetite, sym nervous system, adrenal medulla |
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GnRH - type of receptor, where is R found, main functions (3) |
GPCR reproductive tissues 1. stim release of LH and SFH 2. secondary effects on limbic system 3. acts locally at ovaries/placenta (produced here, and receptors found here) |
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effects of FSH and LH? |
sex specific in general, increase sex steroid production and gametogenesis |
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HPG axis - feedback? what could f up this axis? |
estrogen/progesterone and testosterone are negative regulators -- neg feedback to hyp and ant pit GnRH must be released pulsatile, otherwise FSH and LH become desensitized |
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CRH main function interactions w/ other hormones? |
CRH released in response to stress; stim the ant pit to release products of POMC such as ACTH from corticotrophs VP and angiotension - synergy oxytocin - inhibs the CRH-mediated released of ACTH |
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Feedback loops in HPA axis |
(-) feedback: short - ACTH inhib own secretion (or secretion of CRH) (-) feedback: long - cortisol ... fast = nonnuclear, depends on rate of change of cortisol levels ... slow = nuclear, depends on abs levels of cortisol |
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what mediates release of ACTH |
circadian rhythm -- ACTH + cortisol peak after waking, cortisol decreases throughout the day (low while sleeping) stress stim ACTH |
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thyroid axis - hyp hormone, type of receptor, pit hormone feedback loops? |
TRH from hyp GPCR TSH from ant pit (thyrotroph cells) stim by TRH, inhib by SS (from hyp) inhib by TH (TH, T3, T4) -- (-) feedback loop |
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what is the thyroid axis/regulation (specifically - input + 5b steps) |
input: circ rhythm, cold 1. hyp releases TRH to ant pit 2. pit releases TSH to thyroid 3. thyroid releases TH (T3 + T4) to target tissues and back to hyp and pit for feedback 4. TH transported into cells of target tissues 5a. (-) feedback: serum T3/T4 levels regulate TRH and TSH 5b. (-) feedback: excess iodide inhibits |
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what is T3 known for |
main active nuclear transcription factor of TH |
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lactotrophs - stimulated by? receptor type? they release? |
stim by sleep/stress/suckling stimulation by baby main input from hyp is PIH (inhibitory) - G-alpha-i inhib AC, decrease cAMP release PRL |
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function of PRL? feedback loops? |
men/women - sexual gratification men - sperm production women - menstrual cycle (-) feedback; increases PIF also inhibits GnRH |
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effect of SS on various hormone axes? -- via which receptor?
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inhibs sec of GH and TSH from pit - GPCR G-alpha-i --> inhibs AC, decrease cAMP |
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GHRH receptor type? |
GPCR - G-alpha-s--> stim AC, increases cAMP, increases GH release |
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somatotrophs - effects feedback loops? |
stim prod of IGF-1 direct effects on lipolysis, AA uptake in various tissues, protein synth in liver, opposes insulin actions (-) feedback loops to regulate self -- autocrine |
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which hormones have reciprocal actions on GH? |
SS and GHRH SS inhibs AC, decreases cAMP, less GH GHRH stim AC, increases cAMP, more GH |
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tropic vs trophic |
tropic - stim a particular target gland to release a certain set of hormones trophic - affect growth/nutrition/function of another endocrine gland/cell |
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protein processing |
1. pre-prohormone (not functional): SP + H + CP 2. prehormone (not functional): H + CP 3. mature hormone (functional): CP cleaved at dibasic residues 4. secretion (vesicles) |
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relative concentration of POMC in various lobes of pit? |
int pit: highest concentration, almost completely composed of melanotroph cells ant pit: speckled post pit: virtually no POMC |
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tissue-specific POMC processing? |
ant pit: POMC --> Pro-ACTH --> ACTH (by Prohormone Convertase 1) int pit, skin, hyp: all above steps, plus ACTH --> MSH (by PC2) |
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ACTH controls what...? |
steroid secretion from adrenal cortex - glucocorticoids, mineraliocorticoids, androgens |
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what happens when ACTH binds MCR in the adrenal cortex? |
coupled to G-alpha-s: stim AC, increase cAMP, stim PKA stim prod of adrenal glucocorticoids, mineralocorticoids, androgens (tropic) crucial for development of adrenal cortex (trophic effect) |
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functions of MSH? |
- mammals: stim melanocytes to produce/release melanin (protect skin from UV radiation) - frogs: adaptive coloration (causes dispersal of pigment in melanophores in skin) - radiotrophic fungi: photosynthetic pigment to capture gamma rays and use for energy - protects microbes from temp/chemical damage - in hyp, role in appetite suppression/regulation |
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main regulator of MSH and melanocytes? |
DA from hyp, via int pit |
