Negative feedback

• The process of negative feedback happens automatically without conscious thought
• Negative Feedback

  1. Automatic control systems keep the internal environment stable using negative feedback

  2. When the level of something (e.g. water or glucose) gets too high or too low, the body uses negative feedback to bring it back to normal
• Steps of negative feedback

  1. Receptor detects a stimulus

  2. Coordination centre receives and processes the information, then organises a response

  3. Effector produces a response which counteracts the change and restores the optimum level
• menstrual cycle

  • stage 1: menstruation starts and uterus lining broken down for 4 days
  • stage 2: uterus lining builds up into thick spongy layer ready to recieve fertilised egg
  • stage 3 : egg developed and released into ovaries ( ovulation)
  • stage 4: wall is maintained if no fertilised egg the lining will break down and repeat cycle
• fsh

  • produced in pituitary gland
  • causes egg to mature
  • stimulated ovaries to produce oestrogen
• oestrogen

  • produced in ovaries
  • causes uterus lining to grow
  • stimulates lh
  • inhibits fsh
• Lh

  • produced in pituitary gland
  • stimulates release of an egg
• progesterone

  • produced in ovaries
  • maintains lining of the wall
  • inihibits fsh and Lh
• IVF Can Also Help Couples to Have Children

  If a woman cannot get pregnant using donor sperm, she may choose to try IVF (In Vitro Fertilization) by collecting eggs from the woman's ovaries and fertilizing them in a single to improve the chances of pregnancy. The embryos are given before egg collection to
• Hormones ESH and H can be given to women in a fertility treatment

  Helps a lot of women to get pregnant when previously they couldn't
• thyroxine

  • hormone in thyroid gland
  • regulates metabolism rate
  • stimulates protein synthesis for growth and development
  • thyroxine stimulated by tsh from pituitary glanf
  • tsh inihits thyroxine when to high