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Explain what the reflex arc is, how it is different to how the central nervous system normally works, and how the arc itself works.

To answer this question, you need to know what the reflex arc is and why we need it. The reflex arc is a pathway of neurones (nerve cells) and their connections (synapses) that doesn't go through the conscious part of the brain. This means that they are automatic so you don't have to think about them: your body will just do them if all of the parts of the arc are in tact. Therefore, the difference between a reflex arc is that it does not go through the conscious part of your brain so there is no thought process involved, and they are usually quicker as you don't need to make a decision. This can help us protect ourselves more easily . An example of where this is useful is when you touch a hot object, which I will use as my example when describing the pathway.
Now for how the arc itself works. First, a receptor detects a stimulus from the outside world, for example a hot object. This then stimulates the sensory neurone to send a message down its axon to a synapse at the bottom of the cell. This relays the information to a relay neurone which again sends a message down its own axon to another synapse. The information of the hot object then gets passed to a motor neurone. The motor neurone now has the job of giving the message to an effector, such as a muscle. The effector then acts to protect us, therefore in this example the effector is the muscle in our arm causing the arm to move away quickly away from the hot object and preventing us getting burned.

Answered by Lana B. Biology tutor

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