menstrual cycle

Question 1

menstrual cycle - 4 stages

Answer 1

Stage 1
* day 1 - menstruation. uterus lining breaks down for about 4-5 days
* oestrogen, progesterone, LH levels low
* FSH secreted to stimulate maturation of one follicle in the ovary

Stage 2
* days 5-13
* follicle developed secretes oestrogen
* oestrogen - growth & repair of lining of uterus wall, thick spongy layer of blood vessels. inhibits production of FSH

Stage 3
* oestrogen lvls high enough = stimulates release of LH from pitutiary gland.

Stage 4
* LH triggers formation of corpus luteum from follicle.
* Corpus lutem produces progesterone
* Progesterone maintains thickness of uterine lining for about 14 days until day 28.
* No implantation = corpus luteum breaks down. progesterone lvls drop causing breakdown of uterine lining = menstruation. cycle repeats.

Question 2

hormones

role of FSH in menstrual cycle & in pregnancy
Follicle stimulating hormone

Answer 2

days 1-5 (menstruation)
* FSH secreted to stimulate maturation of follicle in the ovary.
* stimulates ovaries to produce oestrogen (as follicle developed secretes oestrogen)

in pregnancy
inactive

Question 3

hormones

role of oestrogen

Answer 3

days 5-13
* follicle developed produces oestrogen
* oestrogen causes growth & repair of uterine lining (thick, spongy layer full of blood vessels)
* inhibits FSH production

day 14
* when oestrogen lvls are high enough, produces release of LH from pituitary gland

in pregnancy
* high to maintain lining of uterus, stimulate breast growth, development of milk duct.
* produced by placenta

Question 4

hormones

role of LH in menstrual cycle & in pregnancy
luteinising hormone

Answer 4

day 14 - ovulation
* LH peak causes ovulation (release of egg into oviducts)

day 15-28
* triggers formation of corpus luteum from follicle which produces progesterone

in pregnancy
* inactive

Question 5

hormones

role of progesterone in menstrual cycle & in pregnancy

Answer 5

day 15-28
* progesterone secreted by corpus luteum maintains thickness of uterine lining

day 28
* no implantation - corpus luteum breaks down - progesterone lvls drop - causing breakdown of uterine lining - menstruation occurs

in pregnancy
* corpus luteum continues to produce progesterone
* when placenta develops, corpus luteum stops production of progesterone
* placenta produces progesterone instead
* high to maintain lining of uterus, stimulate breast growth, development of milk duct.