There is one primary difference between the somatic nervous system and autonomic nervous system. The somatic nervous system includes all the functions of the body that are done voluntarily, like moving a leg or finger. The autonomic nervous system includes all the functions of the body that are done involuntarily, like breathing or blinking.
The body's nervous system is broken down into the peripheral nervous system and the central nervous system. The central nervous system consists of the brain and spinal cord along with cranial nerves. The peripheral nervous system consists of all the neural pathways that run throughout the rest of the body. Both the somatic and autonomic nervous systems are part of the peripheral nervous system, which means they comprise the area of the nervous system that does not include the brain or spinal cord.
The somatic nervous system is responsible for all voluntary actions via nerve impulses connected from the peripheral nervous system to the muscles of the body, which act according to will in most people. It also is responsible for the input of the senses. When one tastes or touches something, the somatic nerves controls the information being relayed to the brain for interpretation.
The autonomic nervous system controls involuntary actions of the body, like heart rate and perspiration. Within this system, there are two branches: the parasympathetic nervous system and the sympathetic nervous system. The parasympathetic nervous system controls the functions of the body when it is at rest, including salivation, digestion and sexual arousal. The sympathetic nervous system controls the “fight or flight” actions that are the involuntary actions that occur during times of stress or when the body is not at rest.
There is another category of the autonomic nervous system called the enteric system, which is part of the parasympathetic nervous system. This system controls all aspects of digestion, from the esophagus to the large intestine. It is part of the autonomic nervous system because it is responsible for the involuntary actions of digestion.
There are two different types of neurons within the somatic nervous system and autonomic nervous system that carry signals to and from the brain. First, sensory neurons send nerve impulses to the brain and spinal cord, and motor neurons send nerve impulses away from the brain and spinal cord. Sensory neurons are called afferent neurons and motor neurons are called efferent neurons.