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What is the difference b/w the male and female hypothalamus?
surge center in female (defeminized in male)
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The portal system drains into the ________ only.
adenohypophysis/ anterior pituitary/ pars distalis
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In females, there is a pre-ovulatory ________ surge; in males, there is _________.
GnRH; tonic GnRH release
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How does the hypothalamus communicate with the posterior pituitary?
direct release of neuropeptides into capillaries of neurohypophysis
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5 Protein hormones.
oxytocin, GnRH, FSH, Prl, LH
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Protein hormones bind to _______ to...
membrane receptors; activate a signaling cascade.
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3 steroid hormones.
testosterone, estradiol, progesterone
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Steroid hormones cross the ________ to bind to ________ to...
cell membrane; nuclear receptors; activate transcription.
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________ produce steroid hormones from __________.
Gonads; cholesterol
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The LH surge causes _________ production.
progesterone (progesterone during pregnancy inhibits new follicles from developing and ovulating--> to sustain current pregnancy)
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Describe the pathway of LH in a male.
hypothalamus--> GnRH--> anterior pituitary--> LH pulse--> leydig cells--> testosterone production--> sertoli cells--> spermatogenesis OR testosterone--> DHT--> circulation OR testosterone--> estradiol
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Describe the pathway of FSH in a male.
hypothalamus--> GnRH--> anterior pituitary--> FSH--> sertoli cell--> ABP (androgen-binding protein)--> ABP binds testosterone in lumen of seminiferous tubules--> accumulutes in lumen--> critical for normal spermatogenesis
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Why does ABP accumulate in the lumen of the seminiferous tubules and bind testosterone?
ABP is too large to pass through the luminal walls
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Describe negative feedback of GnRH in males.
FSH--> sertoli cells--> inhibin and ABP--> inhibin goes to pituitary--> inhibits FSH secretion
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Describe the pathway of gonadotropins in a female.
LH and FSH stimulate follicular growth--> increase in estradiol--> hypothalamus--> GnRH surge--> anterior pituitary--> LH surge--> ovulation
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Describe negative feedback of GnRH in females.
FSH--> follicle produces inhibin--> inhibin goes to pituitary--> inhibits FSH secretion
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LH affects _______ cells in a female.
theca
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FSH affects ________ cells in a female.
granulosa
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Describe the general pathway for steroid hormones.
steroid secreted by gonad--> enters blood and goes to target tissue--> causes change in target tissue--> steroid in blood passes through liver--> liver renders steroid water soluble--> steroid re-enters blood--> goes to kidney and bile--> excreted in urine and/or feces
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Steroid hormones are metabolized in the _________.
liver
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After steroid hormones have been metabolized, they are excreted as __(2)__.
glucuronide or sulfate
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