Sympathetic Nervous System

Original Editor - lucinda hampton

Top Contributors - Lucinda hampton, Kim Jackson and Ahmed M Diab  

Introduction

The sympathetic nervous system (SNS) is one of the two divisions of the autonomic nervous system (ANS), along with the parasympathetic nervous system (PNS), These systems primarily work unconsciously in opposite ways to regulate many functions and parts of the body.

• The SNS governs the "fight or flight" response while the PNS controls the "rest and digest" response.
• Fibers from the SNS innervate tissues in almost every organ system and provide physiological regulation over diverse body processes including pupil diameter, gut motility (movement), and urinary output.
• The main overall end effect of the SNS is to prepare the body for physical activity, a whole-body reaction affecting many organ systems throughout the body to redirect oxygen-rich blood to areas of the body needed during intense physical demand

Actions

The actions of the sympathetic nervous system occur in concert with other neural or hormonal responses to stress eg increases in corticotropin and cortisol secretion.

In humans, chronic stress results in long-term stimulation of the fight-or-flight response, which leads to constant production and secretion of catecholamines (e.g., epinephrine) and hormones such as cortisol.

Long-term stress-induced secretion of these substances is associated with a variety of physiological consequences eg hyperglycemia (high blood glucose levels), which can lead to type 2 diabetes mellitus, and hypertension (high blood pressure), which can lead to cardiovascular disease.

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