the menstrual cycle Flashcards
where is GnRh produced
the hypothalamus
which gland does the GnRH bind to
binds to receptors on the pituitary gland
what does the pituitary gland produce
LH and FSH
where do LH and FSH travel to
the ovaries via the bloodstream
what does LH and FSH produce when binded to the ovaries
production of oestrogen and inhibin
what impact does oestrogen have on the menstrual cycle
it helps to regulate it
what does inhibin cause
the inhibition of activin which is usually responsible for stimulating GnRH production
What does FSH stimulate
the development of ovarian follicles
what does the follicle most sensitive to FSH become
the dominant Graafian follicle
What does LH cause the Graafian follicle to change into
the corpus luteum
what hormone does the corpus luteum produce
progesterone
What does progesterone stimulate
the endometrium to become receptive to the implantation of a fertilised ovum
what impact does the increased level of oestrogen, progesterone + inhibin have on the pituitary and hypothalamus
negative feedback effect
what does the negative feedback effect on the pituitary and hypothalamus cause
decreased production of GnRH, LH and FSH
what does the decreased production of GnRH, LH and FSH cause
decreased production of oestrogen and inhibin
what happens to GnRH, FSH and LH in pregnancy
they remain inhibited causing menstruation to cease
what is the first phase of the menstrual cycle
follicular phase
what changes occur to FSH levels at the beginning of the menstrual cycle
levels of FSH rise causing stimulation of a few ovarian follicles
what does the first follicle that fully matures produce
large amounts of oestrogen
what does oestrogen do to the other follicles
inhibits growth
what is the follicle that reaches maturity first called
Graafian follicle
what impact does the increased levels of oestrogen cause on the reproductive organs
endometrial thickening, thinning of cervical mucus to allow easier passage of sperm, inhibition of LH production by the pituitary gland
when oestrogen levels surpass a threshold level, what do they stimulate
the production of LH, resulting in a spike in LH levels around day 12
what impact does the rise n LH levels cause on the graafian follicle
cause the membrane of the graafian follicle to become thinner
