Nervous system

• The nervous system allows us to react to our surroundings, and coordinate actions in response to stimuli
• How the nervous system works:

  1. Receptors detect stimuli, and send an electrical impulse.
  2. This electrical impulse travels along sensory neurones to the central nervous system (CNS)
  3. There the information is processed and appropriate response is coordinated.
  4. This response is sent by an electrical impulse, along the motor neurones to effectors.
  5. The effectors carry out the response, either muscles contracting or glands secreting hormones.
• Reflex - a rapid and automatic response to stimulus, which doesn't involve conscious thought.
• How a reflex response happens:

  1. A stimulus is detected by receptors.
  2. Impulses are sent along sensory neuron.
  3. In the CNS, the impulse passes a relay neuron.
  4. Then, impulses are sent along motor neuron.
  5. The impulse reaches an effector, resulting in appropriate response.
• Synapse - gaps between neurons
• How synapses work:

  • When the impulse reaches the end of the first neuron, a chemical is released into the synapse.
  • The chemical diffuses across the synapse.
  • When chemical reaches the second neuron, it triggers the impulse to begin again in the next neuron.