Somatic Nervous System
The somatic nervous system involves the voluntary movement performed by the body. Throughout the body there are sensory neurons that send meassges up to the central nervous system from various parts of the body. Then the central nervous system sends out motor neurons to these parts of the body and this is the response.
Autonomic Nervous System
The autonomic nervous system is another part of the peripheral nervous system. This system includes all of the involuntary movements performed by the body. Some of this involuntary movements include digestion and moving your hand away from a hot object. The autonomic nervous system uses reflexes to react to a situation. Also the autonomic nervous system is divided into the parasympathetic nervous system and the sympathetic nervous system.
Parasympathetic Nervous System
The parasympathetic nervous nervous system is part of the autonomic nervous system. In this system, body functions are slowed down so that energy can be conserved. These body functions are slowed down during times of rest and it includes digestion.
Sympathetic Nervous System
The sympathetic nervous system is the other part of the autonomic nervous system. This nervous system causes your heart rate to increase when a reflex is startled. Also the sympathetic nervous system is involved in maintaining homeostasis. The system is also referred to as "flight or fight response."