The Menstrual Cycle

• Days 1-5: breakdown of the uterus lining
• Week 2 (8-14): uterus gradually building up
• Day 14: Ovulation us the release of an egg from an ovary
• Days 14-16: Fertilisation is most likely to take place
• The lining of the uterus continues to build up throughout weeks 3 and 4
• If Fertilisation does occur then the uterus lining is maintained (so the embryo can obtain nutrients and embed in the lining) and menstruation does not happen
• Contraception is the prevention of fertilisation
• Hormonal contraception includes hormone pills, implants, or injections, and works by releasing hormones to prevent ovulation and thicken mucus at the cervix, preventing sperm from entering
• Barrier methods for contraception include make and female condoms, the diaphragm, caps and sponges. These work by stopping the sperm from reaching the egg
• Hormonal contraceptives are more effective when preventing pregnancy. Condoms helps protect against sexually transmitted diseases (STDs).
• condoms = 98%

  diaphragm/cap = 92-96%

  hormonal methods = >99%
• Oestrogen, progesterone, FSH and LH control the menstrual cycle
• FSH stimulates growth and maturation of follicles
• Low levels of progesterone allow FSH to be released
• Increasing oestrogen causes thickening of wall
• High levels of oestrogen stimulate release of more LH.
• LH triggers ovulation.
• Maturing follicles stimulate oestrogen production.
• Pituitary gland


  Produces FSH
• FSH causes


  Development of a follicle in the ovary
• Follicle


  Produces the hormone oestrogen as the egg develops inside it
• Oestrogen


  Causes growth and repair of the lining of the uterus wall
• Oestrogen


  Inhibits FSH
• High level of oestrogen


  1. Causes a surge in LH from the pituitary

  2. Causes ovulation where an egg is released from the follicle (Day 14 of the cycle)
• Corpus luteum


  Produces oestrogen and progesterone
• Oestrogen and progesterone


  Inhibit FSH and LH production by the pituitary
• Progesterone


  Maintains the uterus lining (the thickness of the uterus wall)
• Egg not fertilised


  1. Corpus luteum dies

  2. Progesterone levels drop

  3. Causes menstruation, where the uterus lining breaks down - this is known as having a period