Synapses and reflexes

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  • Synapses and reflexes
    • synapses
      • A synapse is the connection between two neurones
      • The nerve signal is transferred by chemicals which diffuse across the gap
        • these chemicals then set off a new electrical signal in the next neurone
      • synapses slow down the transmission of a nervous impulse as the diffusion of chemicals across the gap takes time (although is still fairly quick)
    • Reflexes
      • they are fast automatic responses to certain stimuli
      • bypass your brain when a quick response is essential.
      • reduce chance of being injured
      • other examples of reflexes being used
        • if someone shines a bright light in your eyes, pupils automatically get smaller. Means less light enters your eyes stopping them from being damaged
        • if your shocked adrenaline is released automatically It doesn't wait for you to decide if your shocked or scared
    • Reflex arcs
      • the information in a reflex is called a reflex arc
      • the neurones in a reflex arc go through the spinal cord or an unconscious part of the brain
      • 1-a stimulus is detected by receptors and impulses are sent along a sensory neurone to the CNS
        • 2- when the impulses reach a synapse between the sensory neurone and a relay neurone, they trigger chemicals to be released. It is these chemicals that cause impulses to be sent along the relay neurone
      • 2- when the impulses reach a synapse between the sensory neurone and a relay neurone, they trigger chemicals to be released. It is these chemicals that cause impulses to be sent along the relay neurone
      • 3-when the impulses reach a synapse between the relay and motor neurone the same thing occurs. Chemicals are released and sent along the motor neurone
        • 4-the impulses then travel along the motor neurone towards the effector
        • 5-If the effector is a muscle it will contract as a response to the impulse but if it is a gland it will secrete a hormone
        • a reflex arc is quicker as you dont have to think about it

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