A sympathetic or orthosympathetic nerve belongs to the sympathetic nervous system
, which in turn is part of what is called the autonomic or vegetative nervous system. This system is comprised of nerve fibers that primarily innervate organs of the chest cavity or abdomen
, with automatic control of their activities. The sympathetic nervous system functions with the help of two chemical mediators: adrenalin
and noradrenalin, which enable an increase or reduction, depending on which receptor they affect
, in the strength of involuntary functions, in particular that of blood
vessel constriction or dilation, increased cardiac rhythm, and relaxation of certain involuntary muscles
. Sympathetic nerves are frequently stimulated when the body
is being attacked, particularly in order to adapt to systemic consequences by increasing blood pressure
and the force of heart contraction, as well as prioritizing blood supply to what in the past were called the "noble" organs, such as the heart and brain.
Original article published by
. Translated by Jeff
Latest update on August 19, 2014 at 12:21 PM by christelle.b.