hormones

• during puberty reproductive hormones cause secondary sex characteristics to develop
• male:

  • testosterone
  • produced by testes
  • stimulates sperm production
• female:

  • oestrogen
  • produced by ovaries
  • when pubity begins, eggs mature and one is released every 28 days = ovulation
• menstrual cycle:

  • every 28 days, ovulation takes place (ovary releases egg)
  • the uterus lining becomes thick and spongy
  • if sperm present, egg = fertilised to develop baby
  • not fertilised, the egg and uterus lining released (period)
• hormones in menstrual cycle:

  • FSH
  • LH
  • Oestrogen
  • Progesterone
• FSH: causes maturation of an egg in the ovary
• LH: stimulates the release of the egg (ovulation)
• Oestrogen (produced in ovary) and progesterone : involved in maintaining the uterus lining (incase the egg is fertilised)
• menstrual cycle 1:

  FSH is released by the pituitary gland

  travels in the blood to the ovaries, the egg matures

  and FSH triggers ovaries to make oestrogen
• menstrual cycle 2:

  Oestrogen causes the lining of the uterus to become thick

  and stops the pituitary gland from releasing any more FSH, and instead now releasing LH
• menstrual cycle 3:

  LH released by the pituitary gland triggers ovulation, so the mature egg is released

  once the ovary has released the egg, it produced progesterone
• menstrual cycle 4:

  progesterone has 2 effects:

  • stops pituitary gland from releasing LSH and LH - prevents any more eggs from maturing/released
  • keeps the lining of uterus thick incase a fertilised eggs implants

  if no fertilisation , level of progesterone falls

  uterus lining and egg released = period
• • FSH rises, triggers ovaries to release oestrogen
  • as the level of oestrogen increases, this inhibits the production of FSH, so the level of FSH falls
  • oestrogen triggers the release of LH, so LH peaks at day 14
  • LH triggers ovulation which releases progesterone so this releases
  • if no fertilisation , progesterone falls, period

  
• describe how hormones control the menstrual cycle (6)

  • FSH, released from pituitary, stimulates maturation of egg
  • Oestrogen, released from ovary, inhibits FSH production and stimulated LH production
  • LH, released from pituitary, stimulates ovulation
  • progesterone, released from ovary, inhibits FSH and LH production
  • Oestrogen and progesterone maintain the uterus lining