Describe the steps in a reflex arc.

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The reflex arc is a series of events connecting a stimulus to a response. The stimulus, for example a hand touching a hot pan, stimulates the receptor, which could be the sensory receptors in the fingertips. This information travels along a sensory neurone to the coordinator, for example the grey matter of spinal cord. The relay neurone sends information to the relevant motor neurone, which in this scenario stimulates the biceps to contract and withdraw the hand from the potentially harmful hot pan stimulus. The relay neurone also sends messages to the brain so that it is aware of the action taking place.