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

Word History

First Known Use

1850, in the meaning defined above

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 system