reflexes

• What is the motor neurone?

  A neurone that conducts impulses to the effector
• What is the sensory neurone?

  A neurone that conducts the impulses to the central nervous system
• What is the relay neurone?

  A neurone that conducts the impulses from the sensory to motor neurones.
• What are reflex actions?


  Automatic involuntary responses.
• What are synapses?


  Junctions between neurones.
• How does information pass between neurones?

  • An electrical nerve impulse arrives at the end of one neurone.
  • A transmitter chemical is released from this neurone into the synapse.
  • The transmitter chemical moves across the synapse by diffusion.
  • The transmitter chemical binds to the second neurone, generating an electrical impulse.
• How does the nervous system co-ordinate the reflex action?

  • Receptor detects stimulus.
  • Electrical impulses pass along the neurons.
  • They pass from sensory to relay to motor neurons.
  • And the neurotransmitter chemicals are diffused across the synapse to the central nervous system (the spinal cord).
  • This causes a muscle contraction.