What physiological change occurs during the fight-or-flight response?

During the fight-or-flight response, which is mediated by the sympathetic nervous system, the physiological changes are primarily aimed at preparing the body for a rapid response to stress or danger. One of the most notable changes is the increase in heart rate. This occurs due to the release of catecholamines, such as adrenaline (epinephrine), which stimulate the heart to pump more blood. The increased heart rate enhances blood flow to the muscles and vital organs, thereby improving oxygen and nutrient delivery necessary for quick, intense physical activity.

These adaptations are crucial for survival, as they equip the organism to either confront a threat or escape from it efficiently. The increased heart rate is accompanied by other changes, such as increased respiration and heightened alertness, all contributing to the overall state of readiness during the fight-or-flight response.