Psychology MCAT Practice Exam 2026 - Free Practice Questions and Study Guide for Aspiring Psychologists.

The sympathetic nervous system is a crucial component of the body's stress response, commonly referred to as the "fight-or-flight" response. When faced with a threat or stressor, the sympathetic nervous system becomes activated, leading to a series of physiological changes that prepare the body to either confront the danger or flee from it.

This activation results in increased heart rate, elevated blood pressure, enhanced respiratory function, and the release of stress hormones like adrenaline and norepinephrine. These changes collectively enable the body to respond quickly and effectively to perceived threats, enhancing alertness, energy availability, and physical performance.

In contrast, other responses include promoting relaxation and recovery, which is more associated with the parasympathetic nervous system. Inhibiting cognitive functions generally is not a primary role of the sympathetic nervous system; rather, it aims to enhance focus in high-stress scenarios. Additionally, a decrease in heart rate and breathing is associated with a decreased activity level typical of the parasympathetic nervous system. Thus, the sympathetic nervous system's primary function in stress is indeed to activate the fight-or-flight response.