Function

-The ANS is a part of the Peripheral Nervous System.  It is also known as the visceromotor system.

-The actions of the ANS are not under conscious control (involuntary).
-ANS Functions:
1. Controls the viscera of the body. Examples:
  smooth muscle of organs
  cardiac muscle
  glands (such as salivary and adrenal medulla)
  smooth muscle of hair follicles (pilomotor activity)
  smooth muscle of arterioles (vasomotor activity)
  sweat glands (sudomotor activity)
2. Helps maintain homeostasis (with help from somatic motor system & endocrine system).
Homeostatic autonomic reflexes help control physiological parameters like:
  pH of blood
  pCO2, pO2 of blood
  core temperature
  blood pressure
  plasma Na level
   

"Dual Innervation"

-Most organs are innervated by both the sympathetic and parasympathetic divisions of the ANS.
-The sympathetic and parasympathetic innervation of an organ usually oppose each other functionally, examples:
  -miosis and mydriasis of the pupil
  -speeding and slowing of heart rate
  -opening vs. closing of GI sphincters
-Some viscera only receive sympathetic innervation, examples:
  -erector pili muscles (pilomotor function)
  -smooth muscle in arterioles (vasomotor function)
  -smooth muscle of sweat glands (sudomotor function)
  -adrenal glands
 

2003 University of Pennsylvania School of Veterinary Medicine
Faculty: Robert Washabau, VMD, Ph.D., DACVIM
Richard Miselis, VMD, Ph.D
Student: David Paull V'06 
Last updated: Summer 2003