Question

What happens in reflex action?

Answer 1

A reflex action, differently known as a reflex, is an involuntary and nearly instantaneous movement in response to a stimulus.


The causal action (say, getting your knee hit with a hammer) sends nerve signals to your spine. Normally, those would go to your brain, which would decide what to do. Going all the way to the brain takes time, but reflexes want a more immediate answer, so their message only goes to the spine, which says what to do (contract certain muscles!).