2.86 describe the structure and functioning of a simple reflex arc illustrated by the withdrawal of a finger from a hot object.

- the pain receptor is stimulated by the hot pan - electrical impulses travel along the sensory neurone to the central nervous system - in the central nervous system the electrical impulses are passed onto a relay neurone - relay neurones pass the message to a motor neurone (via a synapse) - the electrical impulse will then travel from the motor neurone to the muscle - the muscle contracts and your hand moves away from the hot pan NOTE: the gap inbetween neurones is known as the 'synapse' and messages are passed across these synapses using chemicals Photo credit: Xth notes