The Nervous System and Homeostatis

• The function of the nervous system is to enable organisms to react to their surroundings and coordinate behaviour.
• The two parts of the central nervous system are the brain and spinal cord.
• Reflex actions are rapid and automatic because they do not involve the conscious part of the brain.
• Reflex actions are important for survival and to prevent damage to the body.
• The pathway of a nervous response:

  Stimulus -> receptor -> coordinator -> effector -> response.
• A stimulus is a change in the external or internal environment.
• A synapse is a junction between two neurones where chemicals are released, allowing impulses to cross.
• The function of neurones is to carry electrical impulses around the body.
• Homeostasis is the maintenance of a constant internal environment.
• Homeostasis is important because it maintains optimal conditions for cell and organ function as well as enzyme activity.
• All control systems include receptors, coordination centres and effectors.
• Brain, spinal cord and pancreas are all coordination centres.
• Muscles and glands are both effectors.
• Internal conditions controlled by homeostasis:

  • Body temperature.
  • Blood glucose concentration.
  • Water levels.