Reproductive Hormones

• Puberty is the period in which adolescents start to develop secondary sexual characteristics. Such as facial hair in men (triggered by testosterone) and breasts in women (triggered by oestrogen).
• The average length for a menstrual cycle is 28 days.
• Stage 1 of the menstural sycle is menstruation. This bleeding. It is the break down of the uterus lining and lasts for around 4 days.
• Stage 2 lasts for 10 days. The lining starts to build back up to prepare for a fertilised egg.
• Stage 3 is ovulation. It is when an egg is released from the ovaries.
• Stage 4 lasts for 14 days. It is the maintenance of the uterus lining. If no fertilised egg has reached the uterus then the whole cycle will repeat.
• If a fertilised egg implants, the menstrual cycle stops.
• Oestrogen stimulates the uterus lining to grow.
• Progesterone increases in stage 4 and maintains the lining of the uterus. When progesterone drops the cycle restarts.
• LH and FSH are produced in the pituitary gland. FSH stimulates one of the eggs to mature and LH stimulates the egg to release.
• FSH also stimulates the ovaries to produce oestrogen. When ostregeon gets high it inhibits the production of FSH (negative feedback), it also stimulates the production of LH. Progesterone inhibits both LH and FSH.