Autonomic nervous system

The autonomic nervous system
Blue = parasympathetic
Red = sympathetic

The autonomic nervous system (ANS) controls the conditions inside the body. It is sometimes called the 'visceral nervous system' or 'voluntary nervous system'. The ANS is part of the peripheral nervous system.

Most of its activities are done without the person having conscious control over them. The person usually cannot feel what the ANS is doing. However, some of the ANS's activities some work together with the conscious mind, like with breathing.

The ANS controls many different things, like heart rate, digestion, respiration rate, salivation, perspiration, diameter of the pupils, the discharge of urine, and erection.

There are two different sections within the ANS:

• The sympathetic nervous system, which causes the body to become more active as in the "fight or flight" response.
• The parasympathetic nervous system, which is mostly involved in "rest and digest".

Other websites

• Overview at arizona.edu
• ANS Medical Notes on rahulgladwin.com
• Explanations on the ANS by Dyansys, Inc.

Further reading

• Michael D. Gershon 1998. The second brain. HarperCollins, New York.