Which part of the nervous system is responsible for the "fight or flight" response?

The sympathetic nervous system is responsible for the "fight or flight" response, which is a crucial physiological reaction to perceived threats or danger. When an individual encounters a stressful situation, the sympathetic nervous system activates various bodily functions to prepare the body for rapid action. This includes increasing heart rate, redirecting blood flow to major muscle groups, dilating pupils, and releasing adrenaline. These changes enhance the body's ability to either confront the threat (fight) or flee from it (flight).

In contrast, the parasympathetic nervous system focuses on rest and digestion, promoting a state of calm and energy conservation after stressors have passed. The central nervous system, which consists of the brain and spinal cord, processes information and coordinates the body's responses, but it is the sympathetic division that triggers the acute stress response. The peripheral nervous system refers to all the nerves that branch out from the central nervous system and does not specifically govern the physiological changes seen in the "fight or flight" response. Thus, the sympathetic nervous system is clearly identified as the key player in this urgent and instinctive reaction.