ICL 13.0: The Menstrual Cycle

Question 1

what hormones are present during the early follicular phase?

Answer 1

1. low levels of E2 and progesterone, high levels of GnRH
2. increase FSH leads to recruitment of primary follicles
3. increased E2
4. dominant follicle determined by day 5

Question 2

what hormones are present during the late follicular phase?

Answer 2

1. decreasing FSH/LH due to negative feedback from estradiol

2. increasing number of lH receptors on theca cells

Question 3

how can you have regular periods but not ovulate?

Answer 3

birth control

Question 4

what does estrogen do?

Answer 4

cyclical changes in the vagina and endometrium

it thickens the endometrium

estrogen suppresses GnRH so you don’t have FSH and LH so indirectly it can limit the growth of ovarian follicles

Question 5

what hormone is reduced in athletes triad?

Answer 5

GnRH

Question 6

what finding is most predictive of ovulation?

Answer 6

increased serum progesterone levels

corpus luteum starts releasing progesterone after ovulation has occurred

LH increase doesn’t necessarily mean ovulation has occurred; it means it’s going to occur but what if they don’t even have an ovary?

if you were trying to predict the occurrence of ovulation and when it was going to occur, then you would check LH

Question 7

why would obesity be associated with abnormal or irregular vaginal bleeding?

Answer 7

excess cholesterol can be converted to estrogen

elevated estrogen levels do negative feedback and suppress GnRH levels

also increased estrogen just leads to uncontrolled growing of the endometrium and sloughing because there’s no progesterone to stabilize it so you get lots of breakthrough bleeding

Question 8

why would abnormalities in the thyroid function cause irregular vaginal bleeding?

Answer 8

decreased thyroid hormones causes lack of negative feedback on the hypothalamus and so then the hypothalamus increases TRH which inhibits GnRH release

Question 9

how to OCPs prevent pregnancy?

Answer 9

1. prevent ovulation by inhibiting the release of GnRH
2. thickens cervical mucus
3. thins the endometrium