sympathetic nervous system

/ sĭm′pə-thĕt′ĭk /

1. The part of the autonomic nervous system that tends to act in opposition to the parasympathetic nervous system, as by speeding up the heartbeat and causing contraction of the blood vessels. It regulates the function of the sweat glands and stimulates the secretion of glucose in the liver. The sympathetic nervous system is activated especially under conditions of stress.
2. Compare parasympathetic nervous system