How do hormones affect the menstrual cycle?
There are 3 hormones mentioned in the AQA GCSE Biology specification. These are FSH (follicle stimulating hormone), LH (leuteinising hormone), and oestrogen. FSH and LH are produced by the pituitary gland in the brain. Oestrogen is produced by the ovaries. Progesterone is another hormone which is important to the menstrual cycle.
When progesterone levels are low, FSH is released by the pituitary gland.
Roles of FSH- 1. Causes an egg from the ovaries to mature. 2. Causes the ovaries to produce oestrogen. Roles of oestrogen- 1. Cause (stimulate) the production of LH. 2. Stop (inhibit) the production of FSH. Roles of LH- 1. Cause ovulation (the egg to be released from the ovary). 2. Stimulate progesterone to be produced.
Progesterone stops LH and FSH from being released.Progesterone and oestrogen now maintain the lining of the uterus to prepare for a pregnancy. If there is no pregnancy, progesterone and oestrogen levels drop, and menstruation (bleeding) occurs. Then, the cycle starts again.
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