What division of the autonomic nervous system is responsible for the "fight or flight" response?

The sympathetic division of the autonomic nervous system is responsible for the "fight or flight" response. This physiological reaction prepares the body to respond to a perceived threat or emergency. When activated, the sympathetic system causes a series of responses such as increased heart rate, dilated pupils, and redirected blood flow to the muscles, which facilitates quick reactions.

This system works primarily through the release of neurotransmitters like norepinephrine, leading to increased alertness and energy levels. These changes are crucial for survival in stressful situations, as they enable an individual to either confront or flee from danger.

In contrast, the parasympathetic division promotes a "rest and digest" state, counteracting the effects of the sympathetic division by slowing the heart rate and enhancing digestion, which are not immediately useful in a crisis. The somatic nervous system, responsible for voluntary control over skeletal muscles, and the central nervous system, which includes the brain and spinal cord, are not directly involved in the autonomic responses related to the "fight or flight" mechanism.