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

The sympathetic part of the autonomic nervous system is responsible for the fight or flight response. This system is activated in stressful situations, preparing the body to either confront or flee from perceived threats. When the sympathetic nervous system is engaged, it triggers a series of physiological changes such as increased heart rate, elevated blood pressure, dilation of pupils, and the release of stress hormones like adrenaline. These changes enhance physical performance, alertness, and energy availability, which are essential for responding effectively in emergencies.

In contrast, the parasympathetic system primarily conserves energy and promotes relaxation, which is the opposite of what occurs during a fight or flight response. The cranial nerves are involved in various functions but do not specifically mediate the fight or flight reaction, and the somatic nervous system controls voluntary movements of skeletal muscles rather than the autonomic responses associated with stress.