The autonomic nervous system (ANS) is a division of the peripheral nervous system that influences the function ofinternal organs. The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal.
It is controlled by the hypothalamus.
The sympathetic nervous system is responsible for up- and down-regulating in many homeostatic mechanisms in living organisms. Fibers from the SN innervate tissues in almost every organ system, providing at least some regulatory function to things as diverse as pupil diameter, gut motility, and urinary system output and function.
|Heart||Increases rate and force of contraction|
|Lungs||Dilates bronchioles via circulating adrenaline|
|Blood Vessels||Dilate in skeletal muscle (in animals).|
|Constricts in gastrointestinal organs|
|Sweat Glands||Activates sweat secretion|
|Digestive tract||Inhibits peristalsis|
|Kidney||Increases renin secretion|
|Ductus deferens||Promotes emission prior to ejaculation|
The parasympathetic system is responsible for stimulation of "rest-and-digest" or "feed and breed" activities that occur when the body is at rest, especially after eating, including sexual arousal, salivation, lacrimation (tears), urination, digestion and defecation.
Sympathetic and parasympathetic divisions typically function in opposition to each other.