A reflex action is an instantaneous automatic reaction to a stimulus, typically a pain stimulus. The peripheral nervous system's elements carry out the action. In order for a person to be aware of what has happened, information is sent from the lower portions of the brain to the higher areas once the event is completed.
The reflex arc is the path that a nerve impulse takes when performing a reflex action. The reflex arc's elements are receptors, sensory neuron, inter neuron, motor neuron, effector organ.