The peripheral nervous system works with muscles to execute your body's movement. It does this by the workings of the somatic nervous system. Efferent neurons govern the somatic system. They are the motor neurons that produce your reflexes and the movements about which you are consciously aware. Their direct pathway allows for immediate projection onto muscle. These neurons extend from the spinal cord and relay information to the brain for interpretation.
The autonomic nervous system is composed of two subclassifications known as the sympathetic and the parasympathetic nervous systems. The functions of these two systems generally conflict, as they do in the autonomic and somatic systems. The sympathetic system regulates the stress response when you are in danger, and it is commonly referred to as the fight-or-flight response. It also is active during rest and digestion.
Like the prefix "auto" implies, the autonomic system manages all critical body functions automatically, or without the need for conscious control. Smooth muscles, including the visceral organs, blood vessels, glands and heart, are among the structures controlled by the autonomic system. Functions of these structures do not require conscious thought.
Conversely, the parasympathetic system is at work under normal activity and digestion. Though the sympathetic and parasympathetic nervous systems function simultaneously, one system is always dominant, with the recessive system functioning at a lesser degree. Thus, the differences in the nervous systems allow you to experience a variety of sensations.