• Conditions in our body need to be maintained and controlled so cells can function properly. For example:
    • Osmoregulation: This is the regulation of water content. A balance needs to be kept between water gained and water lost.
    • Thermoregulation: This is the regulation of body temperature. Excess body heat must be lost when you get too hot, but retained when you get too cold.
    • Blood glucose regulation: Blood glucose must be kept at a steady level.

Negative feedback

  • Negative feedback is the mechanism which keeps conditions in our body steady:
    • Changes in the environment trigger a response that counteracts the changes e.g. a rise in body temperature causes a response that lowers body temperature.
    • As a result, the internal environment stays around the norm.
    • This only works within limits – if the environment changes too must it might not be possible to counteract it.


  • When our body temperature gets too low, enzyme-catalysed reactions don’t work properly or fast enough. Cells cannot survive and enzymes are at the risk of denaturing.
  • Body temperature is monitored by the hypothalamus in our brain. It receives impulses from receptors in the skin that provide information about skin temperature.
  • When the hypothalamus detects a change, it causes a response in the dermis of the skin.