Menstrual Cycle

• FSH

  • released by pituitary gland
  • stimulates eggs to develop
  • stimulates ovary to produce oestrogen
• Oestrogen

  • produced by the ovary
  • repairs uterus wall
  • stimulates pituitary gland to produce LH
  • inhibits production of FSH
• LH

  • produced by pituitary gland
  • stimulates ovulation at day 14
  • causes production of progesterone
• Progesterone

  • maintains lining of the uterus
  • inhibits production of LH
  • when at low levels, lining will break down
• STAGE 1: Menstruation starts - uterus lining breaks down ( days 1-4 )
• STAGE 2: Uterus lining thickens ( day 4 -14 )
• STAGE 3: Ovulation - egg is released (day 14)
• STAGE 4: Uterus lining is maintained ( days 14-28 )
• Endocrine system:

  1. sends hormones
  2. hormones travel through blood
  3. slower than nervous system
  4. more widespread
• Hormones are chemical messengers that travel in the blood
• Hormones are produced by endocrine glands, which act on target cells by binding to receptors in the cell membrane of the target cell
• Contraception

  Hormonal disrupts the menstrual cycle

  Non-hormonal creates a barrier to prevent fertilisation of the egg
• Combined pill

  • Progesterone (LH) and oestrogen (FSH) prevents ovulation and thickens mucus
• Mini pill:

  • contains progesterone, inhibiting LH so ovulation stops
  • thickens mucus in cervix - stops sperm from getting through