Oestrogen and progesterone in the control of the menstrual cycle
Several Chemical messenger produced in glands and carried by the blood to specific organs in the body. are involved in the Recurring series of events in the human female reproductive system. of a woman:
- Follicle Stimulating Hormone. It stimulates oestrogen production and the growth of follicles (egg-sacs) in the ovary. It is secreted by the pituitary gland. causes the maturation of an egg in the ovary
- Luteinising Hormone, secreted by the pituitary gland, which stimulates ovulation. stimulates the release of the egg
- A female sex hormone produced in the ovaries, which is responsible for puberty in girls and the regulation of the menstrual cycle. is involved in repairing and thickening the uterus lining, Sex hormone produced by the ovaries and placenta. maintains it
The menstrual cycles last for approximately 28 days, and graphs can be used to follow changes to the hormones during this process.
Question
Describe the relationship between the different hormones during the 28 days.
Days 1 to 12 – oestrogen gradually increases and peaks approximately on the 12th day. Progesterone, LH and FSH stay approximately at the same levels and begin to increase slightly from around day 12.
FSH and LH patterns are very similar and peak during ovulation at approximately 14 days during this cycle. They drop sharply on day 15 and stay constant until day 28.
Oestrogen drops during days 13 and 14, and progesterone continues to gradually increase until about day 21, when it slowly begins to decrease again. Oestrogen mirrors this shape and also has a second lower peak at about day 21.