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

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

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

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

• General adaptation syndrome
• Homeostasis
• Sympathetic nervous system
• Parasympathetic nervous system
• Stress (biology)

See Also

• Adrenaline
• Noradrenaline
• Hypothalamus
• Autonomic nervous system
• Walter Bradford Cannon