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

The "fight or flight" response is primarily mediated by the sympathetic nervous system. This physiological reaction is activated during stressful situations, preparing the body to either confront or flee from perceived threats.

When the sympathetic nervous system is activated, it triggers a series of bodily changes that enhance the ability to respond to danger. These changes include increased heart rate, dilated airways, and the release of adrenaline, all of which work to prepare the body for immediate physical action. This response is evolutionarily advantageous, as it enables quick decision-making and physical readiness when faced with life-threatening situations.

In contrast, while the central nervous system involves the brain and spinal cord and plays a role in processing information and reflexes, it does not directly control the fight or flight reaction. The peripheral nervous system encompasses all nerves outside the central nervous system and includes both the sympathetic and parasympathetic branches. The parasympathetic nervous system, often referred to as the “rest and digest” system, is responsible for calming the body after a stressful event, promoting functions that conserve energy and maintain homeostasis. Hence, the sympathetic nervous system is clearly identified as the two key players when considering the activation associated with the "fight or flight" response.