fightorflightrespons

The fight-or-flight response, also known as acute stress response, is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It is an automatic, involuntary process that prepares the body to either confront the threat or escape from it. This response is mediated by the sympathetic nervous system and the adrenal glands.

When a perceived threat is detected, the hypothalamus in the brain signals the adrenal glands to release hormones, primarily adrenaline (epinephrine) and noradrenaline (norepinephrine). These hormones trigger a cascade of physiological changes. Heart rate increases, blood pressure rises, and blood is shunted away from non-essential organs like the digestive system and towards the muscles and brain. Respiration rate quickens, pupils dilate, and blood sugar levels rise to provide a surge of energy. Muscles tense, and a person may experience heightened senses, tunnel vision, and a feeling of being cold or clammy.

These changes are all designed to enhance the body's ability to either fight the threat head-on or flee from it. Once the perceived threat has passed, the parasympathetic nervous system takes over, initiating the "rest and digest" response, which calms the body down and returns it to its normal state. While a crucial survival mechanism, chronic activation of the fight-or-flight response due to prolonged stress can have detrimental effects on long-term health.