Flight or fight response

Flight or Fight Response

The flight or fight response is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It was first described by Walter Bradford Cannon in the early 20th century. This response is a critical component of the autonomic nervous system and is essential for survival, preparing the body to either fight the threat or flee to safety.

Physiological Mechanisms

The flight or fight response is initiated by the sympathetic nervous system, which is part of the autonomic nervous system. When a threat is perceived, the hypothalamus in the brain activates the sympathetic nervous system by sending signals through the adrenal medulla. This results in the secretion of catecholamines, primarily adrenaline (epinephrine) and noradrenaline (norepinephrine), into the bloodstream.

Effects on the Body

The release of adrenaline and noradrenaline leads to several physiological changes:

• Increased Heart Rate and Blood Pressure: The heart beats faster to pump more blood to the muscles and vital organs.
• Dilation of Airways: The bronchioles in the lungs expand to allow more oxygen to enter the body.
• Increased Blood Glucose Levels: The liver releases glucose into the bloodstream to provide energy to the muscles.
• Dilation of Pupils: The pupils dilate to improve vision and awareness of the surroundings.
• Suppression of Non-Essential Functions: Functions such as digestion and immune response are temporarily suppressed to conserve energy for immediate action.

Psychological Aspects

The flight or fight response is not only a physical reaction but also involves psychological components. The perception of threat can lead to feelings of anxiety, fear, and heightened alertness. These psychological changes prepare an individual to respond quickly to danger.

Evolutionary Perspective

From an evolutionary standpoint, the flight or fight response is an adaptive mechanism that has evolved to increase the chances of survival in dangerous situations. It allows organisms to react swiftly to threats, either by confronting them or escaping.

Clinical Implications

While the flight or fight response is beneficial in acute situations, chronic activation can lead to health problems. Conditions such as chronic stress, anxiety disorders, and post-traumatic stress disorder (PTSD) are associated with prolonged activation of the stress response system.

Also see

• Sympathetic nervous system
• Adrenaline
• Stress (biology)
• Autonomic nervous system
• Anxiety disorder

Resources

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Source: Data courtesy of the U.S. National Library of Medicine. Since the data might have changed, please query MeSH on Flight or fight response for any updates.

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