Reflex Response.

• Reflex P1:

  • A stimulus
  • A receptor that can detect the change in the environment (the stimulus).
  • A sensory neurone that passes the nerve impulse from the receptor to the CNS.
  • An immediate neurone (relay), in the spinal chord, that passes the nervous impulse from sensory to motor neurone.
• Reflex P2:

  • Motor neurone carries nervous impulse from spinal chord to an effector.
  • An effector- a muscle or gland that changes its activity to bring about a response.
• Reflex responses are present to protect the body from damage. The reflex arc does not involve the conscious brain, and only involves 3 neurons and 2 synapses, they respond very quickly.
• A stimulus detected by a receptor causes the potential difference to change. The change in potential difference is called the generator potential.

  If the generator potential reaches a certain level called the threshold it results in an action potential as the channel ions open.