reflexes

• reflexes help prevent injury
• reflexes are rapid, automatic responses to certain stimuli that don't involve the conscious part of the brain - they can reduce the chances of being injured
• the passage of info in a reflex (from receptor to effector) is called the reflex arc
• the reflex arc goes through the CNS
• the neurones in a reflex arc go through the spinal cord or through the unconscious part of the brain
• when a stimulus is detected by receptors, impulses are sent along a sensory neurone to the CNS
• when the impulses reach a synapse between the sensory neurone and the relay neurone they trigger chemicals to be released - these chemicals cause impulses to be sent along the relay neurone
• when the impulses reach a synapse between the relay neurone and a motor neurone, the same thing happens - chemicals are released and cause impulses to be sent along the motor neurone
• the impulses then travel along the motor neurone to the effector
• the muscle then contracts and moves hand away for the stimuli (example)
• reflexes bypass your conscious brain completely when a quick response is essential
• 1. bee stings finger
  2. stimulation of pain receptors
  3. impulses travel along a sensory neurone
  4. impulses are passed along a relay neurone - via a synapse
  5. impulses travel along motor neurone - via a synapse
  6. when impulses reach muscle it contracts
• relay neurones connect sensory neurones to motor neurones
• the electrical impulse bypasses the brain to spped up the impulse getting to the muscle to prevent harm