Reflexes are actions directed by the nervous system that do not require conscious direction or control. Reflexes are characterized as involuntary or voluntary. Reflexes designed to protect the body from injury are termed nociceptive reflexes. Such reflexes include the twitching or winking of the eye, coughing and sneezing to dislodge foreign bodies from the respiratory tract, and gagging (pharynegeal reflex) to as a mechanism to protect the respiratory and digestive tracts.

Under certain conditions it is possible for the body, as a result of experience, to develop rapid responses to certain stimuli so that rapid coordinate movements, such as those associated with running, are possible. These reflexes, however, are not the result of simplified neural pathways, but are the result of conditioning that allows the nearly automatic coordinated movements of many muscles.

Most reflexes require three different neural components within including a sensory neuron, a transmitting neuron, and...