Question

Why do many reflexes, such as pulling your hand away from a hot iron, happen so quickly?

Answer 1

Your nervous system quickly responds to the threat and sends a signal to your brain which causes your muscles/ body to react.
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Answer 2

These reflexes involve relatively few neurons so that they can occur rapidly because the message which neuron carry does not need to go all the way to the brain.

Step-by-step explanation:

Reflexes are responses which quickly occur to protect our body from potentially harmful condition like touching the hot iron. A reflex is a rapid,automatic and unlearned response to a stimulus. These reflexes involve relatively few neurons so that they can occur rapidly because the message which neuron carry does not need to go all the way to the brain.

A reflex occurs when nerve impulses travel through a path which is known as reflex arc. There are five parts in reflex arcs . These are receptors, sensory neurons, inter neurons, motor neurons and effectors.

When we touch something that is very hot, our hand moves away quickly before even we feel the pain. During this reflex action we don’t have to think about it because this reflex does not involve the brain.