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

Mayo Clinic Press notes that anxiety triggers labored breathing, muscle tightening and activation of the sympathetic nervous system, the body’s fight-or-flight wiring. —Allison Palmer, Miami Herald, 6 May 2026

The plunge essentially flips on the sympathetic nervous system, flooding the body with catecholamines that ramp up attention. —Samantha Agate, Charlotte Observer, 6 May 2026

Mayo Clinic Press confirms that anxiety produces real physical responses, including labored breathing, muscle tightening and activation of the sympathetic nervous system. —Allison Palmer, Fort Worth Star-Telegram, 6 May 2026

Mayo Clinic Press notes that anxiety’s physiological response includes labored breath, muscle tightening and activation of the sympathetic nervous system. —Allison Palmer, Kansas City Star, 6 May 2026

Word History

First Known Use

1850, in the meaning defined above

Rhymes for sympathetic nervous system

• cryptosystem
• ecosystem
• intersystem
• multisystem
• photosystem
• subsystem

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