R1 - Menstrual Cycle Flashcards
What happens in a menstrual cycle?
- Follicular phase = Day 1 of menses to LH surge
- Ovulatory phase = LH surge
- Luteal phase = LH surge to menses
___ causes ovarian follicles (granulosa cells) to make estrogen = E
FSH
An ovulated follicle makes a corpus luteum = MAKES ____
– Makes Progesterone = P, Inhibin A and Estrogen
____ GnRH pulses favor LH synthesis
Rapid
____ GnRH pulses favor FSH synthesis (for the next cycle)
Slow
____ inhibits GnRH pulse generator
Progesterone
LH surge
- Triggers ovulation
- Mechanismis unexplained, likely related to reversal of negative E2 inhibition
- Occurs 1 day after estradiol peak
LH surge triggers:
- Resumption of meiosis
- Maturation of oocyte
- Luteinization of granulosa cells
- Expansion of cumulus cells
- Expression of prostaglandins/eicosanoids necessary for follicular rupture
GnRH Agonists
- Bind tightly
- Prevent pulsatile release
- After initial burst suppress LH/FSH and ovarian production
The Ovary
-Several follicles will develop
-One follicle will dominate
-Follicle will ovulate egg
-Ovulated follicle turns into corpus luteum
-CL lives for a finite time
-Dying CL causes hormones to fall
Low, constant ____ feeds back to pituitary to supress FSH and LH
Estrogen
At peak concentrations Estrogen Stimulates
______
LH secretion (LH surge)
After ovulation ____ inhibit FSH
Inhibin A and E
Progesterone inhibits ____ secretion
GnRH
When all hormones fall, decreasing supression reactivates ___ and therefore ___ rises
-GnRH
-FSH
