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sympathetic nervous system
noun
: the part of the autonomic nervous system that contains chiefly adrenergic fibers and tends to depress secretion, decrease the tone and contractility of smooth muscle, and increase heart rate compare parasympathetic nervous system
Examples of sympathetic nervous system in a Sentence
Recent Examples on the Web
Fight or flight gut check The study focused on a subset of the peripheral nervous system called the sympathetic nervous system, which becomes active when the brain detects danger.
—Jon Hamilton, NPR, 12 Dec. 2024
This reaction, triggered by your sympathetic nervous system, is called the fight-or-flight response.
—Anna Giorgi, Verywell Health, 29 Nov. 2024
Anxiety And Stress Are Altered Physiological States Stress and anxiety are a sign of the sympathetic nervous system escalating into the fight-or-flight response.
—Eric Wood, Forbes, 29 Nov. 2024
Criticism triggers the sympathetic nervous system, activating the fight-flight-freeze response—our brain’s natural survival mechanism.
—Jason Walker, Forbes, 14 Oct. 2024
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Word History
First Known Use
1850, in the meaning defined above
Time Traveler
The first known use of sympathetic nervous system was
in 1850
Dictionary Entries Near sympathetic nervous system
Cite this Entry
“Sympathetic nervous system.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/sympathetic%20nervous%20system. Accessed 23 Dec. 2024.
Kids Definition
sympathetic nervous system
noun
: the part of the autonomic nervous system that is concerned especially with preparing the body to react to situations of stress or emergency, that controls expansion of the pupil of the eye and air passages, increases the heart rate, slows digestion, and narrows most blood vessels, and that is made up of nerve fibers that trigger the release of norepinephrine compare parasympathetic nervous system
Medical Definition
sympathetic nervous system
noun
: the part of the autonomic nervous system that is concerned especially with preparing the body to react to situations 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 consists essentially 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 sympathetic chains 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 nerves with which they are distributed to various end organs
called also sympathetic system
compare parasympathetic nervous systemMore from Merriam-Webster on sympathetic nervous system
Britannica.com: Encyclopedia article about sympathetic nervous system
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