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

Criticism triggers the sympathetic nervous system, activating the fight-flight-freeze response—our brain’s natural survival mechanism. —Jason Walker, Forbes, 14 Oct. 2024

When we are presented with stressful situations, our bodies respond by activating the sympathetic nervous system, which increases our blood pressure, heart rate and blood sugar to prepare us to respond to stress. —Peter Stewart, Forbes, 2 Oct. 2024

Casanova added that self-regulating strategies like meditation can help calm the body’s fight-or-flight response, especially when the sympathetic nervous system is activated. —Caitlin Pagán, Verywell Health, 30 Sep. 2024

Caffeine is also believed to stimulate the sympathetic nervous system, which regulates the body’s fight-or-flight response. —Lori Youmshajekian, Scientific American, 13 Aug. 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