Physiology of menstrual cycle

Question 1

Normal menstrual
cycle duration

Answer 1

between
21 and 35 days, average 28 days

A typical period lasts 2 to 7 days with the heaviest
bleeding in the first 3 day

Question 2

HPO axis

Answer 2

1) GNRH from hypothalamus in pulsatile manner to the pituitary
2)GNRH stimulate pituitary gland and it releases FSH and LH
3)LH &FSH stimulates theca and granulosa cells on the ovaries to produce estrogen (negative feedback)
4)ovary releases the ova when LH surge

Question 3

normal Menstrual cycle requires

Answer 3

Normal HPO axis.
Normal endometrial response.
Normal outflow tract .

Question 4

ovarian cycle phases

Answer 4

1) follicular phase
2) ovulation
3) luteal phase

Question 5

uterine cycle phases

Answer 5

1)menses
2)proliferative
3)ovulation
4)secretory

Question 6

how is the production of estrogen by theca and granulosa cells ?

Answer 6

granulosa cells :
FSH stimulates granulosa cells to produce estrogen

theca cells :
LH stimulates theca cells to produce androgen then androgen goes to granulosa cells and converted to estrogen

Question 7

FOLLICULAR PHASE/proliferative
phase

Answer 7

*-Begins with menses on day 1 of the menstrual cycle & ends with
ovulation

**main hormones is FSH and estrogen and LH( in the ovulation )
♥FSH:
chooses one follicle to become mature , surrounded by granulosa and theca
layers
✓ Granulosa cells secret estrogen
✓ Theca cells secret androgen

♥ESTROGEN : acts synergistically with FSH
- induce LH receptors- induce FSH receptors in granulosa & theca cells

♥LH (Luteinizing hormone) :
Acts to rupture the mature follicle (ovulation )

Question 8

endometrium histology

Answer 8

1) functional zone :
-the closest layer to uterine cavity
-contains majority of glands
-undergoes changes with monthly cycle

2) basal zone
-layer just under myometrium
-attaches functional layer to myometrium
-has terminal ends of glands
-remains constant

Question 9

LUTEAL PHASE /secretory phase

Answer 9

-Begins with ovulation on day 14 of the menstrual cycle if (28) days & ends with death of the corpus luteum
* LH SURGE-rupture of the follicle=release ova
* increased progesterone secretion ( from the corpus luteum)
Progesterone supports the secretory phase of the endometrium
When corpus luteum dies  sudden drop in progesterone levels  so leading to shedding of
the prepared endometrial layer

▪ If pregnancy occurs  hCG hormone secretion from the pregnancy maintain the corpus
luteum to secret progesterone to support the pregnancy.