Nervous System

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  • Homeostasis
    • Negative Feedback
      • when level is too high/low
        • effector produces response, counteracts change & restores optimum level
    • Nervous system
      • Central Nervous System (CNS)
        • in animals with backbones, consists of brain & spinal cord, connected to body by sensory & motor neurones
        • coordination centre, sends electrical impulses down other neurones to effectors
      • Effectors
        • bring about a response, usually a muscle which contracts, or a gland which secretes hormones
      • Sensory neurones
        • carry information as electrical impulses from receptors to CNS
      • Motor neurones
        • carry electrical impulses from CNS to effectors
      • Receptors
        • cells that detect stimuli
    • Synapses
      • connection between two neurones
      • nerve signal is transferred by chemicals which diffuse across gap, then set off a new electrical signain next neurone
    • Reflexes
      • help prevent injury, rapid & automatic responses to certain stimuli
        • don't involve conscious part of brain
          • in bright light, our pupils dilate, stops it getting damaged
      • goes through spinal cord through unconscious part of brain
        • when a stimulus detected by receptors, impulses sent along a sensory neurone to a relay neurone in CNS
          • impulses reach a synapse between s&r neurone
            • they trigger chem. to be released, cause impulses to be sent along relay neurone
      • stimulus
        • receptor
          • sensory
            • relay
              • motor
                • effector


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