homeostasis

• homeostasis is the maintenance of a constant internal environment despite changes in the external environment
• automatic control systems consist of:

  .receptors

  .co-ordination centres

  .effectors
• negative feedback is when the body responds to a stimulus to restore normal conditions
• the nervous system is the communication system of the body, it is made up of the brain, spinal cord and nerves
• neurones (nerve cells) carry electrical impulses around the body
• neurones are thin, long and have branched connections
• the central nervous system consists of the brain and spinal cord