The autonomic nervous system (ANS) is made up of the sympathetic, parasympathetic, and enteric nervous systems. ¹
These three systems work together to maintain homeostasis, or your body’s ability to regulate normal function. ²
The ANS is responsible for all the body functions that we do automatically, without consciously thinking about performing. ³
The sympathetic nervous system usually stimulates organs (sometimes known as fight or flight.) ⁴
Sympathetic nervous system activation results in elevated blood pressure and heart rate, constriction of blood vessels, reduced digestion, dilation or opening of the airways, and more. ⁵
The parasympathetic nervous system maintains normal body functions (sometimes known as rest and digest.) ⁶
It can cause a decrease in heart rate and blood pressure, stimulate digestion, and more. ⁷ It is regulated mainly by the vagus nerve. ⁸
Sometimes, the sympathetic nervous system and parasympathetic nervous systems act as opposites, and sometimes they work together. ⁹
The enteric nervous system controls the muscle contractions, secretions, absorption, and blood flow during digestion. ¹⁰
