Definition:
The sympathetic nervous system is part of the autonomic nervous system (ANS), which is responsible for helping to regulate a variety of body functions, including heart rate, breathing, sweating, and digestion.
The sympathetic nervous system works in conjunction with another branch of the ANS, the parasympathetic nervous system. Whereas the parasympathetic nervous system slows the body's functions to allow processes such as digestion to occur, the sympathetic nervous system provides quick responses to immediate needs (e.g., responses to present threats.) For example, the sympathetic nervous system increases heart rate, respiration, and perspiration to ready our body for "fight or flight."
