Difference
The sympathetic nervous system prepares the body for the “fight or flight” response during any potential danger. On the other hand, the parasympathetic nervous system inhibits the body from overworking and restores the body to a calm and composed state.
Examples of parasympathetic responses
An easy acronym to remember how and where the PSNS works is SLUDD. This stands for:
Salivation: As part of its rest-and-digest function, the PSNS stimulates production of saliva, which contains enzymes to help your food digest.
Lacrimation: Lacrimation is a fancy word for making tears. Tears keep your eyes lubricated, preserving their delicate tissues.
Urination: The PSNS contracts the bladder, which squeezes it so urine can come out.
Digestion: The PSNS stimulates the release of saliva to promote digestion. It also enacts peristalsis, or the movement of the stomach and intestines, to digest food as well as release bile for the body to digest fats.
Defecation: The PSNS constricts the sphincters in the intestine and moves digested food material down the digestive tract so a person can have a bowel movement.
Examples of the Sympathetic Nervous System Response
The classic case of SNS response is a physical danger, especially with a potential predator, and the preparation of the body for either fight-or-flight. The overall system is designed to enhance voluntary muscle activity while shutting down all non-essential functions.
Arterioles and veins in most vascular beds constrict, reducing blood flow to the skin and digestive organs. Sphincters in the digestive organs also constrict, to control the flow of food from one organ to the next. However, coronary blood vessels, pulmonary circulation and parts of the respiratory tree respond with dilation, to enhance cardiac output. The heart beats with greater contractile force and at a higher frequency as well. Vasoconstriction in many parts of the body also increases blood pressure.
Similarity
Both are the part of ANS. Both originate from the spinal cord. Both have huge influence on physiological process of the body such as respiration, circulation, digestion, urination and reproduction.
