menstruation physiology Flashcards
when is the follicular phase?
first 14 days
how does the follicular phase start?
menstruation of previous cycle
how long does follicular phase usually last ?
14 days
hormonal changes that occur in follicular phase?
initial fall in oestrogen and prog triggering menstruation
steady increase in FSH and LH
steady increase in the amount of oestrogen
increase in FSH and LH stimulates?
completion of the first meiotic division to form the secondary follicle
what essentially happens during the follicular phase?
the follicles are stimulated to grow. One of the follicles becomes dominant and is released by the ovum.
when does the luteal phase begin?
when the ovum is released
there is a surge in two hormones at ovulation. what are they?
LH and FSH
surge in what stimulates ovulation?
LH
when does ovulation actually occur?
12-36 hours after LH surge
how long is the luteal phase?
14 days
levels of LH, FSH and oestrogen in luteal phase?
decrease
what is there an increase in production of in luteal phase ?
progesterone
how does progesterone act to maintain the endometrium and prepare it for implantation?
increased glandular secretion and vascularity
what is progesterone produced by?
the corpus luteum
what is the corpus luteum?
left over follicle (without the egg)
what happens to the corpus luteum if fertilisation doesn’t occur?
the corpus lute begins to degenerate and the amount of progesterone produced goes down
what stimulates the corpus lutuem to continue producing progesterone?
the embryo produces HCG which stimulates the maintenance of the corpus luteum and therefore maintenance of a viable endometrium
what triggers ovulation?
LH surge
is responsible for growth of endometrium and secondary sexual characteristics
oestrogen
stimulates switch from negative to positive feedback and the LH surge?
oestrogen peak
a normal cycle is said to last ?
21-35 days
the hormone of pregnancy as it acts to maintain the endometrium and levels peak after ovulation
progesterone
eventually, what takes over in the production of progesterone?
placenta