That part of the nervous system involved in the regulation of the heartbeat, glandular secretions, and smooth muscle contraction and relaxation, and generally not subject to conscious control.
The nervous system regulating tissues and functions not normally under conscious control, such as heartbeat and blood pressure. It is divided into the sympathetic and parasympathetic nervous systems which have opposite effects on the cardiovascular system. When stimulated, the sympathetic nerves increase heart rate and myocardial contractility, constrict blood vessels and raise blood pressure, whereas the parasympathetic nerves decrease heart rate, relax blood vessels and lower blood pressure. See also sympathetic nervous system and parasympathetic nervous system.
The part of the body's complex system of nerves that controls the involuntary activity of some of the internal organs, such as breathing or heartbeat.