Reflexes

Reflexes

A reflex occurs when a nerve impulse passes over a reflex arc, in response to a stimulus, a change in the environment that affects receptors in the organism. Reflexes are either voluntary or involuntary according to where and why they occur. An example of an involuntary response is the knee jerk reflex, which occurs in response to tapping of the tendon in the knee, causing the tendon and muscles to stretch. [CG] {NR}