Which 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, which prepares the body to respond to perceived threats or emergencies. When activated, this system triggers a series of physiological changes that mobilize energy and resources to either confront or escape from danger.

These changes include an increase in heart rate and blood pressure, dilation of the airways for easier breathing, and redirection of blood flow to the muscles, enhancing physical performance. Hormones such as adrenaline (epinephrine) are released to further heighten alertness and improve the body's capabilities in a stressful situation.

In contrast, the parasympathetic division promotes a state of rest and relaxation in the body, often referred to as "rest and digest," counteracting the effects of the sympathetic division. The central nervous system, which includes the brain and spinal cord, integrates information but does not directly manage the autonomic responses. The somatic nervous system controls voluntary muscle movements and is not involved in the autonomic response to stress.

Thus, the sympathetic division's activation is crucial for the body's short-term survival during stressful encounters.