sympathetic nervous system

American  

noun

1. Anatomy. the part of the autonomic nervous system consisting of nerves that arise from the thoracic and lumbar regions of the spinal cord, functioning in opposition to the parasympathetic nervous system, and producing effects such as increasing the heart rate and dilating the pupils.

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sympathetic nervous system Scientific  

/ sĭm′pə-thĕt′ĭk /

1. The part of the autonomic nervous system that tends to act in opposition to the parasympathetic nervous system, as by speeding up the heartbeat and causing contraction of the blood vessels. It regulates the function of the sweat glands and stimulates the secretion of glucose in the liver. The sympathetic nervous system is activated especially under conditions of stress.

2. Compare parasympathetic nervous system

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Example Sentences

A cold plunge can even result in a brief euphoric feeling as your body switches from the parasympathetic to sympathetic nervous system.

From The Wall Street Journal • Nov. 7, 2025

"Patients with HD have a slightly more active sympathetic nervous system, which is what drives the fight or flight response, and theoretically have more norepinephrine," Schultz explains.

From Science Daily • Dec. 2, 2024

But the study from Domingos and results from other groups including Imai’s, which pinpointed specific neurons, indicate the sympathetic nervous system plays a bigger role in basic metabolism than expected.

From Science Magazine • May 22, 2024

But for many, the sympathetic nervous system is out of balance with the parasympathetic nervous system, which, along with the vagus nerve, works to calm the body.

From Salon • Apr. 3, 2024

These glands, which are each made up of two opposing structures, stand in intimate relation to the sympathetic nervous system and secrete a substance called adrenalin.

From The Foundations of Personality by Myerson, Abraham