2.1 HPG axis lecture: males Flashcards
where do FSH and LH act on in males? via?
primarily on gonads
via Gas (G alpha s)
PCR –> adenylate cyclase
which cells are of importance in the male testis?
Sertoli cells
Leydig cells
what is the function of LSH and LH in males? called?
stimulate sex hormone synthesis (steroidgenesis)
control gamete production (spermatogenesis)
where does LH act within the testis? function?
Leydig cells produce testosterone (leading to androgenic effects e.g. behavioural effects on CNS)
what is the negative feedback control of LH?
testosterone reduces GnRH secretion from hypothalamus
therefore AP secretion of LH AND FSH is reduced
(reduce LH + FSH - BOTH)
where does FSH act within the testis? function?
Sertoli cells
secrete inhibin and spermatogenesis (sperm cells)
function of inhibin?
(FSH –> sertoli cells –> inhibin)
negative feedback on hypothalamus and AP, reduce JUST FSH secretion (selective inhibition)
effect of testosterone (Leydig cells) on Sertoli cells?
(slight) positive feedback - stimulate Sertoli cells to secrete inhibin and spermatogenesis
where are FSH receptors found?
on Sertoli cells of seminiferous tubules
what effect does FSH have on testis?
cause Sertoli cells to grow and secrete spermatogenic substances
what does FSH require in order to function on Sertoli cells of testis?
needs testosterone which diffuses into seminiferous tubules
what is inhibin secretion related to?
developing gametes (sperm cells)
in the medium long term, how are testosterone levels like?
constant
what is testosterone levels fluctuated by during the day?
- circadian rhythm: highest early morning
2. effects of environmental stimuli: both driven by brain
