Reflexes

A reflex is a quick action your body makes without you having to think about it. Signals travel along nerves to your spinal cord and back, which is much faster than sending a message all the way to the brain. Blinking and pulling your hand away from heat are common reflexes.

Doctors often test reflexes by tapping just below the knee with a small hammer. A healthy knee-jerk reflex happens in less than a tenth of a second, so reflexes help keep us safe from danger.