Definition: Sympathetic Nervous System, SNS

Sympathetic Nervous System, SNS

The SNS is one branch of the Autonomic Nervous System ANS, which work together but in opposition to the Parasympathetic Nervous System, PNS, in order to control the involuntary functioning of our internal organs and endocrine glands.

The Sympathetic Nervous System is dominant when energy is required for action, particularly in emergency situations, when it can activate the startle reaction and the fight /flight response.

Please see the entry for the Autonomic Nervous System for further details about the functions of the SNS.