controlling fertility

• this is where hormones in the menstrual cycle interact for the menstryal cycle to take place
• 1. the pituitary gland produces FSH which stimulates the development of a follicle in the ovary
  2. the egg matures in the follicle and the follicle produces oestrogen
  3. oestrogen causes growth and repair of the lining of the uterus wall and inhibits the production of FSH
• 4. when oestrogen levels are high enough it stimulates the release of LH from the pituitary gland which causes ovulation (day 14)

  5. the follicle becomes a corpus luteum and produces progesterone

  6. progesterone maintains the lining of the uterus
• if the egg isn't fertilised the corpus luteum breaks down and progesterone levels drop. this leads to menstruation
• if fertilisation occurs the corpus luteum continues to produce progesterone which prevents the lining of the uterus from breaking down. once the placenta has developed it secretes progesterone and continues this to maintain the lining during pregnancy