The Sympathetic and Parasympathetic Nervous Systems The autonomic nervous system is behaviors that are involuntary to the nervous system. An example of this is when your eyes dilate according to the amount of lighting around you. The autonomic nervous system is subdivided into two parts, the sympathetic nervous system and the parasympathetic nervous system. Most organs in the autonomic nervous system is monitored and managed by both the sympathetic and parasympathetic neurons. Sympathetic and parasympathetic have polar affects of each other; therefore, having this king of organizational structure helps maintain homeostasis.
Some examples of this include: eye dilation, salivation, heartbeat, lung constriction and dilation, peristalsis and secretion, bile control, adrenaline and bladder movements. The sympathetic nervous system accelerates the heart rate while the parasympathetic nervous system slows it down. Your sympathetic nervous system constricts bronchi while the parasympathetic nervous system dilates the bronchi. Your sympathetic nervous system inhibits flow of the saliva while your parasympathetic nervous system stimulates the flow of saliva. The sympathetic nervous system also inhibits peristalsis and secretion while the parasympathetic nervous system stimulates it. The sympathetic nervous system also converts glycogen to glucose while the parasympathetic nervous system stimulates the release of bile. The sympathetic nervous system controls the secretion of adrenaline and noradrenaline. Also, the sympathetic nervous system inhibits bladder contraction and the parasympathetic nervous system contracts the bladder. The sympathetic and parasympathetic nervous systems are large parts of the autonomic nervous system that allows us not to voluntarily think about doing an action. They control some of the very most important actions of the body.