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The nervous system

Reflex arc

Reflex reactions in humans are controlled by the reflex arc.

When the safety of an organism demands a very quick response, the signals may be passed directly from a sensory neuron, via a relay neurone, to a motor neurone for instant, unthinking action. This is a reflex action.

A reflex arc is the nerve pathway which makes such a fast, automatic response possible. It does not matter how brainy you are - you will always pull your hand away from a flame without thinking about it. It is in-built, or innate, behaviour, and we all behave in the same way. The animation allows you to go through the stages of the reflex arc one by one:

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