Walter Cannon - Fight or Flight & Importance of Homeostasis

Walter Cannon is responsible for coining and researching some key concepts about stress such as "fight or flight" and "homeostasis". His scientific research demonstrates and explores the interrelationship of stress & change, mind & body.


Born in 1871 in Prairie du Chien Wisconsin, Walter Cannon became a respected physiologist and neurologist who helped to significantly advance our understanding of stress.

Fight of Flight - the Stress Response
Shows the Mind Body Connection

Early in his career, Cannon studied digestion in animals. He was one of the first researchers to use X rays in physiological studies.

He noticed that when the animals he was working with were anxious or frightened their stomach motility (digestion) was inhibited. This led him to explore the relationship between mental/ emotional states and physiological functioning.

That our mental and emotional states affect how our bodies work is now a key concept in mind body medicine.

Walter Cannon’s work showed that the major emotions involve the excitation of the sympathetic division of the autonomic nervous system. This excitation leads to many changes in a body’s smooth muscles, glands and bodily functions such as increased secretion of adrenaline, increased heart rate, blood pressure, perspiration, and decreased stomach motility.

Today these changes are all well known symptoms of what can be called a stress response.

In 1915 he published Bodily Changes in Pain, Hunger, Fear and Range and coined the term fight or flight to describe an animal’s response to threats.

Walter Cannon on Importance of Homeostasis - Maintaining Balance and Stability for Health

In 1932 Walter Cannon published The Wisdom of the Body. In this work, he coined the term “homeostasis” to describe the body’s process of maintaining inner constancy of key biological systems in order to maintain health. This was based on the prior work of Claude Bernard who refereed to the “milieu interieur”, or internal environment which a body must maintain.

In very simple terms, homeostasis can be understood as the body’s process of maintaining the required stability in the functioning of bodily systems so that life and health can continue.

Some examples of homeostasis in humans are the following processes:

  • Body temperature is maintained within a required range,
  • The response of the immune system to bacteria and viruses,
  • The clotting of blood when bleeding has occurred,
  • The repair and regeneration of damaged tissues,
  • The maintenance of fluid and electrolyte balance,
  • The control of glucose levels, and
  • The acid-base regulation involving the blood and kidneys.

Discussion -

Health can be understood a dynamic process of successfully adapting and maintaining the required biological stability in the midst of ever changing conditions.

When homeostasis is overwhelmed by change then a stress response and illness can result.

While fight or flight indicates a stressful response of the body to perceived danger, homeostasis is the body's tendency to preserve the stable conditions necessary for life and health in the midst of the challenges of change.

When we take measures to enhance the body's ability to maintain homeostasis we enhance the body's health.

Read about Healthy Lifestyle Choices which help to prevent stress, or

Return to Define Stress, or

Explore an overview of many ways to reduce stress by visiting
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"Cannon, Walter Bradford." Encyclopaedia Britannica from Encyclopaedia Britannica 2007 Deluxe Edition. (2009)

"feeling." Encyclopaedia Britannica from Encyclopaedia Britannica 2007 Deluxe Edition. (2009)

"homeostasis." Encyclopædia Britannica from Encyclopædia Britannica 2007 Deluxe Edition. (2009).

"human disease." Encyclopædia Britannica from Encyclopædia Britannica 2007 Deluxe Edition. (2009).

"endocrine system, human." Encyclopædia Britannica from Encyclopædia Britannica 2007 Deluxe Edition. (2009).

Wikipedia. 2009. "Walter Bradford Cannon."

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