Which term refers to the reaction to immediate danger, often resulting in physical response changes?

The term that refers to the reaction to immediate danger, often resulting in physical response changes, is acute stress. Acute stress is characterized by the body's swift response to a threat or challenge, leading to a physiological reaction that prepares an individual to either confront or flee from the danger, commonly known as the fight-or-flight response. This includes changes such as increased heart rate, heightened alertness, and a surge of adrenaline.

In contrast, chronic stress pertains to prolonged exposure to stressful situations, leading to accumulation of stress-related issues over time, rather than an immediate reaction. Cognitive stress involves mental processes related to perception and decision-making under pressure but doesn't specifically relate to a physical response to danger. Emotional stress refers to the psychological impact and feelings of anxiety or distress that come from stressors, but again does not directly define the immediate, physical reaction to danger that acute stress does.