The fight or flight response and the autonomic nervous system

The 'fight or flight' response is a fundamental physiological mechanism that is activated by the perception of a threat or danger, preparing the organism to either face the challenge or escape from it. This reaction is mediated by the Autonomic Nervous System (ANS) and is crucial for survival.

The Autonomic Nervous System (ANS)

The ANS regulates involuntary bodily functions, such as heart rate, breathing, digestion, and blood pressure.

It is divided into two main branches with opposing but complementary functions:

• Sympathetic Nervous System (SNS): It is responsible for activating the "fight or flight" response.

• It prepares the body for action and energy expenditure.

• Parasympathetic Nervous System (PNS): Promotes relaxation, energy conservation, and recovery after a period of activation.

Activation of the Sympathetic Nervous System in the Face of a Threat

When danger is perceived, the SNS is rapidly activated, triggering a cascade of physiological changes:

• Release of Adrenaline and Noradrenaline: These hormones increase heart rate and blood pressure, sending more blood to the muscles.

• Accelerated Breathing: To increase oxygenation.

• Dilated Pupils: To improve vision.

• Increased Muscle Tension: Preparing muscles for action.

• Blood Flow Redirection: Less blood to organs not essential for immediate response (such as the digestive system) and more to the muscles and brain.

• Glucose Release: To provide quick energy.

All of these changes are designed to maximize the body's ability to fight or flee effectively.

Consequences of Activation in Anxiety

In anxiety disorders, this "fight-or-flight" response may be activated inappropriately or excessively, even in the absence of real danger.

The accompanying intense physical sensations (palpitations, shortness of breath, dizziness, tension) may be misinterpreted as dangerous in themselves (e.g., as a heart attack), which in turn increases anxiety, creating a vicious cycle.

Understanding the nature of this physiological response is an important step in treating anxiety, as it allows the person to recognize that these sensations, although unpleasant, are not dangerous and are part of a natural survival mechanism.