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| sympathetic nervous system
n. The part of the autonomic nervous system originating in the thoracic and lumbar regions of the spinal cord that in general inhibits or opposes the physiological effects of the parasympathetic nervous system, as in tending to reduce digestive secretions, speeding up the heart, and contracting blood vessels. |
| The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2006 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved. |
Sympathetic nervous system
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| © 2008 Encyclopædia Britannica, Inc. |
| sympathetic nervous system | |
noun | |
| originates in the thoracic regions of the spinal cord; opposes physiological effects of the parasympathetic: reduces digestive secretions; speeds the heart; contracts blood vessels |
| WordNet® 3.0, © 2006 by Princeton University. |
sympathetic nervous system
 Audio Help (sĭm'pə-thět'ĭk) Pronunciation Key
The part of the autonomic nervous system that tends to act in opposition to the parasympathetic nervous system, as by speeding up the heartbeat and causing contraction of the blood vessels. It regulates the function of the sweat glands and stimulates the secretion of glucose in the liver. The sympathetic nervous system is activated especially under conditions of stress. Compare parasympathetic nervous system. |
| The American Heritage® Science Dictionary Copyright © 2002 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved. |
sympathetic nervous system n.
The part of the autonomic nervous system originating in the thoracic and lumbar regions of the spinal cord that in general inhibits or opposes the physiological effects of the parasympathetic nervous system, as in tending to reduce digestive secretions or speed up the heart.
| The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company. |
Main Entry: sympathetic nervous system
Function: noun
: the part of the autonomic nervous system that is concerned especially with preparing the body to react tosituations of stress or emergency, that contains chiefly adrenergic fibers and tends to depress secretion, decrease the tone and contractility of smooth muscle, increase heart rate, and that consistsessentially of preganglionic fibers arising in the thoracic and upper lumbar parts of the spinal cord and passing through delicate white rami communicantes to ganglia located in a pair of sympatheticchains situated one on each side of the spinal column or to more peripheral ganglia or ganglionated plexuses and postganglionic fibers passing typically through gray rami communicantes to spinal nerveswith which they are distributed to various end organs called also sympathetic system; —compare
| Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc. |
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