Autonomic nervous system: Difference between revisions

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imported>Robert Badgett
(New page: thumb|479px|The autonomic nervous system<br/>Blue = parasympathetic<BR>Red = sympathetic The '''autonomic nervous system''' ('''ANS''') (or '''visceral nervous syste...)
 
imported>Robert Badgett
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===Sympathetic nervous system===
===Sympathetic nervous system===
{{main|Sympathetic nervous system}}
{{main|Sympathetic nervous system}}
Promotes a "[[fight or flight]]" response, corresponds with arousal and energy generation, inhibits digestion:
Promotes a "[[fight or flight]]" response, corresponds with arousal and energy generation, inhibits digestion.
====Function====
* Diverts blood flow away from the gastro-intestinal (GI) tract and [[skin]] via vasoconstriction.
*  Blood flow to [[skeletal muscle]]s, the [[lung]] is not only maintained, but enhanced (by as much as 1200%, in the case of skeletal muscles).
* Dilates bronchioles of the lung, which allows for greater alveolar oxygen exchange.
* Increases [[heart rate]] and the [[contractility]] of cardiac cells ([[myocytes]]), thereby providing a mechanism for the enhanced blood flow to skeletal muscles.
* Dilates pupils and relaxes the lens, allowing more light to enter the [[eye]].


===Parasympathetic nervous system===
===Parasympathetic nervous system===
{{Main|Parasympathetic nervous system}}
{{Main|Parasympathetic nervous system}}
Promotes a "rest and digest" response; promotes calming of the nerves return to regular function, and enhances digestion.
Promotes a "rest and digest" response; promotes calming of the nerves return to regular function, and enhances digestion.
====Function====
* Dilates blood vessels leading to the GI tract, increasing blood flow. This is important following the consumption of food, due to the greater metabolic demands placed on the body by the gut.
*The parasympathetic nervous system can also constrict the bronchiolar diameter when the need for oxygen has diminished.
* During accommodation, the parasympathetic nervous system causes constriction of the pupil and lens.
* The parasympathetic nervous system stimulates salivary gland secretion, and accelerates [[peristalsis]], so, in keeping with the rest and digest functions, appropriate PNS activity mediates digestion of food and indirectly, the absorption of nutrients.
* Is also involved in erection of genitals, via the [[pelvic splanchnic nerves]] 2–4.


== See also ==
== See also ==

Revision as of 12:35, 21 January 2008

The autonomic nervous system
Blue = parasympathetic
Red = sympathetic

The autonomic nervous system (ANS) (or visceral nervous system) is the part of the peripheral nervous system that acts as a control system, maintaining homeostasis in the body. These maintenance activities are primarily performed without conscious control or sensation. The ANS has far reaching effects, including: heart rate, digestion, respiration rate, salivation, perspiration, diameter of the pupils, micturition (the discharge of urine), and sexual arousal. Whereas most of its actions are involuntary, some ANS functions work in tandem with the conscious mind, such as breathing. Its main components are its sensory system, motor system (comprised of the parasympathetic nervous system and sympathetic nervous system), and the enteric nervous system.

Components

Sympathetic nervous system

For more information, see: Sympathetic nervous system.

Promotes a "fight or flight" response, corresponds with arousal and energy generation, inhibits digestion.

Parasympathetic nervous system

For more information, see: Parasympathetic nervous system.

Promotes a "rest and digest" response; promotes calming of the nerves return to regular function, and enhances digestion.

See also

References

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