Menstruation and Hormones
The “female” hormones are responsible for the menstrual cycle. The hormones that are most involved in the process include the following:
Rising levels of estrogen are responsible for the build up of the uterine lining (endometrium). This build up of the lining gets the uterus ready to accept a fertilized egg. As the cycle continues, and no pregnancy occurs, the levels of estrogen decrease. Decreasing estrogen loosens the support for the built up lining and helps to make it separate, and prepare for menses.
This hormone is made by the pituitary gland. Its purpose is to get a follicle ready for ovulation. Every month between 3 and 30 follicles are ripened for ovulation but usually only one continues to grow and eventually ruptures and releases an egg during ovulation.
This is the hormone that makes the egg (follicle) release from the ovary. This hormone is involved in the process of ovulation – the time in the menstrual cycle when the follicle ruptures and releases the egg from the ovary.
This hormone is released by the ruptured follicle (one that has released an egg). After the egg is released from the follicle, the follicle closes and becomes a corpus luteum. The corpus luteum secretes increasing amounts of progesterone. This rise in the level of progesterone typically causes a rise in body temperature. If no pregnancy occurs, the levels of progesterone falls and this along with the decreasing amount of estrogen, helps the built up lining of the uterus to separate and for menstruation to begin.