What is the Origin of Fight-or-Flight Response?

Described initially by Walter Cannon, this physiological response is hardwired into the autonomic nervous system to ensure immediate survival against perceived physical threat. The term perfectly captures the dichotomous immediate behavioral options available to the organism.

What is the Mechanism of Fight-or-Flight Response?

Sensory input rapidly triggers the hypothalamus, activating the sympathetic outflow to the adrenal medulla, resulting in a surge of circulating catecholamines, namely epinephrine and norepinephrine. Simultaneously, the HPA axis initiates a slower but more sustained release of cortisol, preparing the body's metabolic resources for immediate expenditure.

Fight-or-Flight Response

Meaning

The acute neuroendocrine reaction to perceived danger, mobilizing the organism for immediate confrontation or escape via sympathetic nervous system activation. This ancient survival mechanism prioritizes rapid energy mobilization over long-term maintenance functions. It is the foundational response to acute threat detection.