The nervous system of the body is a complex structure of basically two categories of nerves. The first is what most of us are familiar with, somatic nerves. The second is called the autonomic nervous system. As the name suggests, autonomic nerves travel to and function in body systems that are beyond our control.
The autonomic nervous system is divided into two categories sympathetic and parasympathetic.
The sympathetic system, broadly speaking, is a group of fine nerves that supply various organs, blood vessels, parts of the skin, and especially areas of the heart. This system is activated during instances where the organism is required to have increased mobility, better vision, and a faster response time.
The parasympathetic system is summarized as “rest and digest.”
This system is involved in processes that involve increasing nutrition and growth for the organism. Increasing blood flow and even causing drowsiness for restful sleep.