Automatic Body Response

Automatic body responses or reflexes as they are commonly known as are involuntary and near instantaneous movement in response to stimulus.  Reflexes can be grouped into categories such as conditioned, primitive, stretch, or cranial.  Each type named for the either the part of the body they effect or how they are obtained.  For example, stretch reflexes generally have to do with the peripheral nervous system moving muscles.  A conditioned reflex on the other hand is something that can be "taught" to to person or animal through continued stimulus.

The body reacts to stimuli through an exchange of information from the peripheral nervous system to the central nervous system where the brain connects the stimulus to an appropriate action.  Then this information is transmitted again to the peripheral nervous system to act on the decision.  This whole process while much too fast to compare to the macro movement of the body is still too slow when in the perspective of fear and actual danger.  So that's when reflexes are triggered.  Reflexes are essentially the peripheral nervous system overriding the controls and acting when certain stimuli interact with it.  This is known as a "reflex arc".  A reflex arc is when the two types of neurons found in the body act independently of each other one (interneuron) reports to the spine and brain while the other (motor neuron) is already triggering a response.  Allowing the body to move away from danger quickly while still informing the brain.