So Im a little lost in the menstrual cycle please help!
Alright so birth control pills function by producing an increase in estrogen & progesterone hormone levels, which inhibits LH & FSH, yes? If LH & FSH are never rising, then ovulation isn't going to occur because ...the corpus letum never develops, yes? I interpret this as the corpus letum will never atrophy, and in turn no "sloughing off" of the endometrium will occur, so how is menstruation occurring in women taking birth control pills? I think my misunderstanding is the menstruation phase and what is actually happening. THanks!
ok, you are right until the ovulation part.
1. Ovulation: The normal of estrogen inhibits ovulation, but the slowly increase of estrogen would cause LH surge, means a sudden release of large does of LH. It's the LH surge that pops the egg out or ovulate. But if we provide our body with steady amount of estrogen instead of varying the amount like we normally would, then LH surge would never happen, and we would never ovulate.
2. The endometrium breaks down because at the last 7 days of our cycle, estrogen and progeterone level is super low. This superlow of both hormone triggers the collapse of the endometrium.
How did the estrogen and progesterone became super low?
a. in normal circumstances, that one is not taking birth control pill, that one is ovulating. Estrogen is produced by this theca cell in the follicle. But after ovulation, the corpus luteum takes over and not only that it makes estrogen, it makes progesterone as well. That's why the progesterone level is super low until after ovulation. After ovulation progesterone level will rise to a certain point and then drop to super low again. Because the if one doesn't get pregnant, the corpus leteum dies slowly. Estrogen does this rise then fall thing after ovulation as well. Because after ovulation the theca cell in the follicle becomes the corpus leteum. But remember that progesterone is super low the entire time until after ovulation, but estrogen is at OKAY high level the whole time. For the precise level of each hormoen please refer to the graph. It's because this rise and fall of both the estrogen and progesterone that cuased the endometrium to collapse.
b. In a different scenario, that one takes the birth control pill. The package comes with 28 pill. The first 21 pills gives you steady level of hormone, estrogen and progesterone. But the last 7 pills are empty pills or sugar pills or pill that contains no hormone at all. Estrogen and progesterone dropped to super low cuz the last 7 pills contains nothing. Then we menstruate.
View attachment 350px-MenstrualCycle2_en.svg.png