Human Nervous System

• What is a reflex action?

  Reflex actions are automatic and rapid; they do not involve the conscious part of the brain
• The Nervous System

  • Very fast and sends precise electrical impulses through nerves
  • Quicker than the Endocrine System
• Role of the Nervous System

  • Enables humans to react to their surroundings and to coordinate their behaviour
• How does Information get around in the Nervous System?

  • Information from receptors passes along cells (neurones) as electrical impulses to the central nervous system (CNS).
  • The CNS is the brain and spinal cord.
  • The CNS coordinates the response of effectors which may be muscles contracting or glands secreting hormones
• The Reflex Arc

  1. There is a Stimulus
  2. Receptors detect the stimuli
  3. Passed onto the Sensory Neurone
  4. Passed onto the Synapse Relay Neurone
  5. Passed onto the Spinal Cord
  6. Passed onto the Motor Neurone
  7. Effector, carries out the Response
• Role of the Synapse

  • When an Impulse reaches the end of a Neurone, a chemical known as a neurotransmitter is released across the Gap
  • The chemical diffuses across the Synapse
  • When the Chemical reaches the next neurone, thus starts another Impulse