homeostasis

• negative feedback


  There's an optimum condition and then there would be a change away from the optimum. receptors will detect this change. communication system informs effector to react to reverse these changes - this makes it return to the optimum condition
• positive feedback


  when a change happens which takes it away from optimum, a receptor detects change which then has the communication system inform the effector. This makes the effector increase change.
• negative feedback (rising temperature)

  • thermoregulatory centre in hypothalamus detects change
  • nervous and hormonal systems carry signals to skin, liver and muscles
  • less heat generated and more heat lost - temperature falls
• negative feedback (fall in temperature)

  • thermoregulatory centre in hypothalamus detects change
  • nervous and hormonal systems carry signals to skin, liver and muscles
  • more heat generated and less heat lost - temperature rises