Synapses & Reflexes

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Created by
ali G

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  • Neurones transmit information very quickly to and from the brain, and your brain quickly decides how to respond to a stimulus. But reflexes are even quicker
  • Synapses connect neurones
  • Theconnection between 2 neurones is called a synapse
  • The nerve signal is transferred by chemicals which diffuse across the gap between the neurones. These chemicals then set off a new electrical signal in the next neurone
  • 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 ofbeing injured
  • For example, if someone shines a bright light in your eyes, your pupils automatically get smaller so less light gets into the eye - this stops it from getting damaged
  • If you get a shock, your body releases the hormone adrenaline automatically - it doesn't wait for you to decide that you're shocked
  • The passage of information in a reflex (from receptor to effector) is called a reflex arc
  • The reflex acr goes through the CNS
  • Relay neurones connect sensory neurones to motor neurones
  • The neurones in reflex arcs go through the spinal cord or through an unconscious part of the brain
  • Relay neurones carry nerve impulses within the CNS
  • When a stimulus (e.g. bee sting) is detected by receptors, impulses are sent along a sensory neurone to a relay neurone in 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, chemicals are released and cause impulses to be sent along the motor neurone
  • The impulses then travel along the motor neurone to the effector (which is ususally a muscle). The muscle then contracts and moves your hand away
    1. Bee stings finger
  • 2. Stimulation of the pain receptor
  • 3. Impulses travel along the sensory neurone
  • 4. Impulses are passed along a relay neurone, via synapses
  • 5. Impulses travel along a motor neurone, via a synapse
  • 6. When impulses reach muscle, it contracts
  • Because you don't have to think about the response, reflexes are quicker than normal responses