reproductive physiology Flashcards
what is the sex HPG axis
hypothalamus release GnRH –> ant pit releases LH and FSH –> testes/ ovaries –> testosterone and oestrogen reduce GnRH from hypothalamus
what does FSH do in females
causes growth of follicles + secretion of oestrogen and oestradiol
what does LH do in females
after ovulation, causes corpus luteum to produce progestogen and prepares for pregnancy
what does FSH do in males
causes sperm production
what does LH do in males
causes testes to secrete testosterone
what activates the GnRH receptor in the hypothalamus
kisspeptin
what type of hormone is GnRH
neuropeptide
what is different about the release of GnRH in females vs males
females is pulsatile manner!! males is steady
what does low frequency pulsation in the hypothalamus cause in females
low frequency = FSH = oestrogen. oestrogen then becomes concentrated and increases pulsation
what does high frequency pulsation in the hypothalamus cause in females
high frequency = LH = progestogen - increased progesterone reduces pulsation and completes negative feedback loop
what happens to GnRH in the onset of puberty in females
GnRH pulsation
what does GnRH pulsation control in females
menstrual cycle
when is the follicular phase of the menstrual cycle
day 1-14 (pre-ovulation)
what hormone increases in the follicular phase and what is released from the developing follicles
FSH increases and follicles release oestrogen
what does concentrating oestrogen cause just before ovulation
LH surge
when does ovulation begin
34-36 hours after LH surge
what happens to a woman’s body temp during ovulation
increases by 1C
what happens in the luteal phase
preparation for pregnancy: formation of corpus luteum from empty follicle which secretes progesterone
what is the longest a menstrual cycle can last and still be normal
35 days
what is a follicle
an oocyte surrounded by antrum (fluid), theca cells and granulosa cells
what does growth of a follicle mean
increased number of fluid and surrounding cells - NOT increased egg numbers
what does progesterone do to the follicle
breaks down the antrum so the oocyte is released (ovulation)
how do theca and granulosa cells produce oestrogen
theca cells (activated by LH) covert cholesterol –> androgen and granulosa cells (activated by FSH) then convert androgen to oestrogen
what enzyme converts androgens to oestrogen in granulosa cells
aromatase
when do follicles start to grow
puberty
what is a dominant follicle
one that can cope with decreased FSH
what cells form luteal cells after ovulation
granulosa and theca cells
what does the corpus luteum secrete in the luteal phase
progesterone
what happens do the corpus luteum if the egg is not fertilised
stops secreting progesterone and dies
in a fertilised egg what does the embryo secrete
HCG
what secretes oestrogens
follicles and adrenal cortex
what effect does oestrogen have on the womb (2)
increases thickness of vaginal and uterus wall for implantation, decreases viscocity of mucous
what effect does oestrogen have on LH and pH (3)
regulates LH surge, reduces vaginal LH and reduces lactic acid pH
what effect does progesterone have on the womb (4)
maintains endometrium thickness, makes the mucous thick again, relaxes smooth muscle in pregnancy, increases body temp
where is sperm made
testes
what hormone in males decreases FSH to reduce spermogenesis
inhibin
what cells produce testosterone and what hormone are they influenced by
Leydig cells under LH control
what does testosterone travel bound to
SHBG and albumin
what is testosterone converted into
dihydrotestosterone and oestradiol
what happens on day one of the mentrual cycle
bleeding
what does oligomenorrhea mean
long cycles >35 days
what does amenorrhea mean
absent periods
what does menorrhagia mean
heavy periods
what does dysmenorrhea mean
painful periods
what is primary hypogonadism
problem in the ovaries/ testes and high LH/FSH = hypergonadotrophic hypogonadism
what can cause primary hypogonadism
premature ovarian failure, klinefelter’s syndrome, chemo
what is secondary hypogonadism
problem with the pituitary/ hypothalamus - hypogonadotrophic hypogonadism
what can cause secondary hypogonadism
kallman syndrome, head injuries, anorexia
