Male Reproductive Physiology Flashcards
When it comes to the expression of the a and b chains of LH and FSH, what seems to determine of rate of gene expression respectively?
The “Rhythm” of GnRH secretion
As a Leydig cell within the teste, the ability to secrete testosterone is facilitated by what component of the cell? Stimulating hormone?
LH receptor; LH
As a Sertoli cell in the teste, the ability to produce androgen binding protein is facilitated by what component of the cell? Stimulating hormone?
FSH receptor; FSH
What is the hormone which facilitates negative feedback of anterior pituitary, produced by the sertoli cell? What hormone is it inhibiting the synthesis of in the anterior pituitary?
Inhibin; FSH
What hormone produced by leydig cells is able to negatively regulate its own production?
Testosterone; inhibits GnRH and LH release
As it pertains to the HPT axis, there only need be a low amount of testosterone in circulation compared to the extremely high concentration of it within the seminiferous tubules of the testes (intra-testicular). That said, if an individual receives a dosing of exogenous steroids, this actually decreases endogenous testosterone production. How/why?
Bc the amount of circulating testosterone is maintained at a relatively low level, the HPT axis is acutely sensitive to an increase in this level. As a result, this will lead to the inhibition of GnRH and activity of pituitary gonadotrophs (meaning decreased LH production).
In addition to androgen binding protein (AR) and anti-mullerian hormone, what else do sertoli cells produce?
Aromatase *converts testosterone to estrogen which supplies sperm w/estrogen bc sperm have ER*
In men what is the primary source of estrogen production?
peripheral (in adipocytes) conversion of testosterone to estrogen
What is the process of spermiation?
releasing of spermatozoa into seminiferous tubule
In adults, as long as there is sufficient levels of testosterone there need not be overly high levels of what 2 hormones in order to maintain sufficient spermatogenesis?
LH and FSH
The whole process of sperm maturation takes 74 days whereby about 50 of those days are spent in the seminiferous tubule whereas the other 24 are spent where?
Epididymis
We know already that the middle piece of the spermatozoa is where flagellar motion originates. What about the head, principle, and end piece?
Head: - Acromosomal cap which contains hydrolytic and proteolytic enzymes Principle piece: - Stores ATP End piece or tail: - Flagellum
The temperature of the scrotum is required to be 1-2 degrees (C) cooler than the core body temp in order to promote spermatogenesis. In an effort to facilitate this need, the scrotum has two different muscles which will simultaneously contract or relax depending on the weather. What are the names of these muscles?
Tunica Dartos External Cremaster *contract to pull testes closer to body in cold weather and relax to have testes fall away in warm weather
What is the first sign of puberty?
Pulsatile release of GnRH from the hypothalamus during REM sleep
Once the pulsatile release of GnRH by the hypothalamus is recognized by the anterior pituitary, this stimulates the production/release of LH and FSH. Why does increased release of GnRH facilitate a more ideal environment for puberty?
GnRH decreases sensitivity of both hypothalamic and gonadotrophic cells to circulating sex steroids. Therefore a greater concentration of sex steroids is needed to create negative feedback.
