synapses and reflexes

• what do synapses do?

  connect neurones
• synapse - the nerve signal is transferred by chemicals which diffuses across the gap which set off a new electrical signal to the next neurone
• reflexes help prevent injury
• reflexes are rapid automatic responses to certain stimuli
• the reflex arc:

  • the neurones in a reflection arc go through the spinal cord
  • when a stimulus is detected by receptors, impulses are sent along a sensory neurone to a relay neurone
  • when the impulses reach a synapse between a sensory neurone they trigger chemicals to be released which causes impulses to be sent along the relay neurone
  • when the impulses reach a synapse between the relay neurone and a motor neurone, chemicals are again released so impulses are sent along the motor neurone
  • they travel to the effector
  • the muscle contracts