The Autonomic Nervous Nervous System

The autonomic nervous system is a special part of the peripheral nervous system. The autonomic nervous system regulates such automatic bodily processes as breathing and digestion without conscious control by the brain. This constant regulation enables the body to maintain a stable internal environment. The autonomic nervous system has two parts, the sympathetic system and the parasympathetic system. The sympathetic system responds to the body's needs during increased activity and in emergencies. The actions of the sympathetic system include speeding up the heartbeat, sending additional blood to the muscles, and enlarging the pupils of the eyes to use all available light. The parasympathetic system, in general, opposes the actions of the sympathetic system. The parasympathetic system's functions include slowing down the heartbeat, diverting blood from the muscles to the stomach and intestines, and contracting the pupils of the eyes. The balance of activity between the two systems is controlled by the central nervous system.