NCIt definition : The part of the autonomic nervous system comprising paired, paraspinal sympathetic
trunks together with their branches, plexi, and subsidiary ganglia; it functions to
mobilize the body for activity and opposes the physiological effects of the parasympathetic
nervous system.;
Alternative definition : NCI-GLOSS: The part of the nervous system that increases heart rate, blood pressure,
breathing rate, and pupil size. It also causes blood vessels to narrow and decreases
digestive juices.;