The Menstrual Cycle
Sex hormones
Oestrogen and Testosterone are released by reproductive organs and stimulate the release of growth hormone.
- An increase in these hormones happens during puberty.
- Testosterone is produced by the testes
- Oestrogen is produced by the ovaries
Why do girls have periods?
Periods are caused by hormone levels changing within the body, these changes happen during puberty.
It is natures way of preparing the body for having a baby. Periods are part of the female reproductive cycle called the menstrual cycle
The Menstrual Cycle
It involves the preparation of the uterus lining so that it is able to receive a fertilised egg. This happens once a month (28 days approximately) until menopause.
If an egg is fertilised it can implant itself in the prepared uterus lining. If it is not fertilised the lining breaks down and is lost in a period
Blood flow may be heavier in the first few days. The average blood loss is only around 80ml (roughly 3 tablespoons)
Throughout the cycle the levels of hormones change. The cycle is controlled by the hormones oestrogen and progesterone
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