Topic 5- Reflex Action

Topic 5- Reflex Action

1. What is a reflex action?

   • rapid automatic response of the nervous system
   • unconscious- does not involve the brain
   • protects us from danger or harm

2. Order of events (use diagram numbers)

   • 1. A pin hurts (stimulus) a finger
     • 2. A receptor detects the pin (stimulus)
       • 3. The receptor sends electrical impulses to the sensory neurone
         • 4. At the end of the sensory neurone, the electrical impulses are passed to the relay neurone by chemicals diffusing through the synapse
           • 5. The chemicals cause electrical impulses to be sent along the relay neurone
             • 6. At the end of the relay neurone, the electrical impulses are passed to the motor neurone by chemical diffusion through the synapse
               • 7. The chemicals cause electrical impulses to be sent along the motor neurone
                 • 8. The motor neurone sends electrical impulses to the effector
                   • 9. The muscle (effector) contracts and the arm moves away from the pin (response).

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