Bitesize has changed! We're updating subjects as fast as we can. Visit our new site to find Bitesize guides and clips - and tell us what you think!


The nervous system

Central nervous system

An animal's response to a stimulus is coordinated by its central nervous system (CNS). The CNS consists of the brain and the spinal cord. It gathers information about, and responds to, changes in the environment.

Receptors detect a stimulus and send impulses along sensory neuronssensory: Sensory neurones carry messages from sense organs into the CNS to the CNS. The CNS coordinates the information and sends impulses along motor neurons to the effectors, which bring about a response. The sequence is as follows:

  1. Stimulus
  2. Receptor
  3. Sensory neuron
  4. Central nervous system
  5. Motor neuron
  6. Effector
  7. Response

The peripheral nervous system

The peripheral nervous system (PNS) consists of motor and sensory neurons that carry impulses from the receptors to the CNS, as well as impulses from the CNS to the effectors.

Back to Brain and mind index

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.