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

The reflex arc is an innate system. That means that we are born with it and it is our body's way of unconsciously protecting us from danger. For example, if your hand is near flame, your skin is full of sensory neurons that detect the change in temperature and register it as a threat. Then this is communicated to a relay neuron withing your central nervous system (brain or spinal cord). The relay neurons job is is to get an effector (muscle) to react. For this example, it would be a muscle in your arm that would flex in order to move your hand away from the flame. This is your reflex response.