Give an example of how a reflex arc works.

1. A receptor detects a stimulus (such as a hot surface)
2. then the sensory neurone sends electrical impulses to the relay neurone crossing over a synapse
3. then the relay neurone sends this impulse to the motor neurone over the synapse which sends this to the effector ( a muscle which will pull the hand away from the hot surface for example)

For example, a reflex arc below is described for when we touch something hot

1) Receptors in our finger detect the stimulus (change in the environment-in this case the heat).

2) The receptors send this signal as information along a sensory neurone to the CNS (brain and spinal cord)

3) The CNS comes up with an effective response to protect us- in this case moving our finger away quickly

4) This information about the response is sent along the motor neurone to a muscle which will tell it to contract and pull our finger away from the heat.

A relay neurone is an interneurone connecting the motor and sensory neurone