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Oestrogen causes puberty in female bodies.
- During puberty, a child's body starts developing into an adult's body.
- The hormone oestrogen is responsible for the female secondary sexual characteristic changes during puberty.
- One of the most important changes during puberty for females is the beginning of the menstrual cycle.
Menstrual Cycle
Every month, a woman's body undergoes change to prepare for the possibility of pregnancy.
- An egg is released from one of the ovaries every month. This is called ovulation.
- To prepare for pregnancy, the lining of the uterus becomes thicker and richer in blood vessels.
- If pregnancy does not happen, the uterus lining is shed. This is called menstruation.
There are 4 different hormones that control the menstrual cycle.
👇 For IGCSE Biology, it is important to understand how different hormones control the menstrual cycle. 👇
1. FSH (follicle-stimulating hormone)
- During the early days of the menstrual cycle, FSH is released by the pituitary gland.
- The release of FSH is responsible for maturing of the egg in the ovary.
- The maturing egg produces the hormone oestrogen.
2. Oestrogen
- The uterus lining becomes thicker and richer in blood vessels as oestrogen level rises.
- High levels of oestrogen stimulates the pituitary gland to release LH (luteinising hormone).
- The level of oestrogen peaks one or two days before ovulation.
3. LH (luteinising hormone)
- A sharp increase in the level of FSH and LH triggers the ovary to release the egg (ovulation). Ovulation happens at approximately day 14 of the menstrual cycle.
4. Progesteron
- After the release of the egg, progesteron is produced.
- Progesteron is responsible for maintaining the thick lining of the uterus.
- If fertilization has occurred, progesteron will keep being released to maintain the uterus lining.
- If fertilization has not occurred, progesteron levels will drop, which results in the shedding of uterus lining (menstruation).