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

DEFINITION
Reflex: an automatic reaction - an action performed without conscious thought in response to a stimulus

DOWN TO BUSINESS NOW

1. Sense organ detects stimulus (let's say a hot object)
2. Sensory neurone carries electrical impulse to CNS (central nervous system)
3. Relay neurone carries impulse through CNS where a response is decided to the motor neurone
4. Motor neurone carries impulse to effector (eg muscle)
5. Response is executed (eg you pull your hand away from a hot object)

HERE'S A LINK TO THE NERVE SONG 

http://scicast.org.uk/films/2011/06/the-nerve-song.html