Fight-or-flight response
Overview
The fight-or-flight response is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. This response was first described by Walter Bradford Cannon, a physiologist at Harvard University, who coined the term to explain the body's natural response to stressors Cannon (1929).
Physiology
The fight-or-flight response is a complex sequence of physiological changes that prepare the body for action. These changes are initiated by the sympathetic nervous system, which stimulates the adrenal glands to release hormones such as adrenaline (epinephrine) and noradrenaline (norepinephrine). These hormones cause a variety of changes in the body, including increased heart rate, blood pressure, and blood glucose levels, as well as dilation of the pupils and bronchioles to improve vision and oxygen intake respectively.
Role of the Amygdala
The amygdala, an almond-shaped structure in the brain, plays a crucial role in triggering the fight-or-flight response. It processes emotional information, particularly fear-related stimuli, and sends signals to the hypothalamus, which in turn activates the sympathetic nervous system.
Evolutionary Perspective
From an evolutionary perspective, the fight-or-flight response has been crucial for survival. It allows individuals to respond quickly to threats in their environment, either by fighting off the threat or fleeing from it. This response is not unique to humans and is observed in many animal species.
Modern Implications
In modern times, the fight-or-flight response can be triggered by non-life-threatening situations such as work-related stress, traffic jams, or public speaking. Chronic activation of this response can lead to health issues such as heart disease, diabetes, and mental health disorders like anxiety and depression.