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

Never Taking a Day Off Chronic working overtime keeps your sympathetic nervous system activated, leading to burnout, mood disorders, and weakened immunity. —Sherri Gordon, Health, 17 June 2025

Chronic stress, when the sympathetic nervous system doesn’t have a chance to release control, stimulates cortisol production. —Shani Harmon, Forbes, 23 Jan. 2025

When someone encounters a threat, the sympathetic nervous system stimulates the adrenal glands to release the stress hormones adrenaline and cortisol. —Angela Ryan Lee, Verywell Health, 28 May 2025

The sympathetic nervous system is activated when the body senses a threat, and the adrenal glands release cortisol. —Helen Carefoot, Verywell Health, 16 May 2025

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