Sex Steroids Biochemistry Flashcards
What are the pituitary gonadotrophic n hormones
FSH
LH
whats the role of FSH in women
stimulates the development of the follicle
stimulates the release of oestrogen
what is the role of FSH in men
regulates spermatogenesis
What roll does LH play in women
stimulates ovulation and production of progesterone from the corpus luteum
what does LH do in men
stimulates production of testosterone
what has a -ve feedback effect on the pituitary/hypothalamus in men
testosterone
what has a -ve feedback affect on the pituitary/hypothalamus in women
oestrogen
also has a +ve feedback affect at times
what is the role of Gonadotrophin releasing hormone
secreted by the hypothalamus to target the pituitary causing the release of FSH and LH
what is GnRH released in a pulsatile manner
because increased pulse frequency causes LH secretion and decreased pulse frequency causes FSH production
what are GnRH pulses like in men
constant and don’t vary
what hormone regulates the change in pulse rate from low to high (FSH to LH)
oestrogen
what hormones regulates GnRH frequency from high to low (LH back to FSH)
progesterone
what happens to GnRH in puberty
A steady acceleration of pulsatility
a peak at night in males causing high testosterone levels in the morning
What regulates GnRH
Kisspeptin
which phase of the menstrual cycle is variable
follicular
typically 14 days (+/- 7 days)
which phase of the menstrual cycle isn’t variable
luteal (14 days)
how does FSH cause oestrogen increase
is causes the follicle to develop and secrete oestrogen
what stimulates ovulation
high oestrogen levels causing the LH surge
what is a follicle
a oocyte surrounded by follicular cells (granulosa and theca cells)
what happens as the follicle grows
increase in the number of follicular cells but still only 1 oocyte
why do the follicular cells fill with cholesterol in folliculogenesis
so that they can produce and pump out loads of progesterone
follicular cells become luteal cells
When multiple eggs are going through folliculogenisis how is one picked for ovulation
early stages of ovulogeneiss is independent on gonadotrophin
once it reaches a certain size it becomes dependent
when the FSH levels dip some follicles are lost as they can’t cope
the one that copes the best due to increased vascular supply, or increased FSH receptors is the dominant one selected for ovulation
