Fight-or-flight response

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The fight-or-flight response (also known as the acute stress 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 part of the autonomic nervous system and involves the activation of the sympathetic nervous system, resulting in the release of hormones such as adrenaline and noradrenaline.

Physiological Mechanism[edit | edit source]

When an individual perceives a threat, the hypothalamus activates the sympathetic nervous system. This leads to the release of adrenaline from the adrenal medulla. The release of these hormones results in several physiological changes, including:

  • Increased heart rate (tachycardia)
  • Increased blood pressure
  • Dilation of the bronchioles in the lungs
  • Redistribution of blood flow to the muscles
  • Dilation of the pupils
  • Inhibition of non-essential systems such as digestion

These changes prepare the body to either fight the threat or flee from it, hence the term "fight-or-flight."

Historical Background[edit | edit source]

The concept of the fight-or-flight response was first introduced by Walter Bradford Cannon in his work on the homeostasis of the body. Cannon's research demonstrated that the body's response to stress is a complex, coordinated effort involving multiple systems.

Role in Modern Medicine[edit | edit source]

Understanding the fight-or-flight response is crucial in the field of psychology and medicine. It is a fundamental concept in the study of stress and anxiety disorders. Conditions such as post-traumatic stress disorder (PTSD) and panic disorder are closely related to the dysregulation of this response.

Related Concepts[edit | edit source]

See Also[edit | edit source]

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External Links[edit | edit source]


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Contributors: Prab R. Tumpati, MD