The Role of the Nervous System in Reflexes

A reflex is an involuntary response to a stimulus. When pain is felt on your fingertips, a single neuron detects it and sends a signal down through the length of the arm to the spinal cord. It arrives at the spinal cord via something called the dorsal root. And yes, it sounds crazy that it is one neuron from your fingertip all the way to the spinal Cord, but that is what it is.