والتر كانون

والتر كانون Walter Bradford Cannon
ولد في	19 أكتوبر، 1871 ويسكنسن
توفي في	19 أكتوبر، 1945
الجنسية	أمريكي
مجال البحث	الفيزيولوجيا
المؤسسات	مدرسة طب هارفرد
اشتهر بسبب	الاستتباب الكر والفر الأشعة السينية Cannon-Bard theory

والتر كانون (بالإنجليزية: Walter Bradford Cannon) (ولد 19 أكتوبر، 1871 - توفي 19 أكتوبر، 1945) هو فيزيولوجي أمريكي، أستاذ ورئيس قسم الفيزيولوجيا في مدرسة طب هارفرد، والذي ساعد في تطوير مفهوم الاستتباب (بالإنجليزية: homeostasis) مع كلود برنار (بالإنجليزية: Claude Bernard)، و أشهر ذلك من خلال كتابه حكمة الجسم (بالإنجليزية: The Wisdom of the Body) في عام 1932.

أعماله

المساهمات العلمية

Use of salts of heavy metals in X-Rays

He was one of the first researchers to mix salts of heavy metals (including bismuth subnitrate, bismuth oxychloride, and barium sulfate) into foodstuffs in order to improve the contrast of X-ray images of the digestive tract. The barium meal is a modern derivative of this research.

نظرية الكر والفر

In 1915, he coined the term fight or flight to describe an animal's response to threats (Bodily Changes in Pain, Hunger, Fear and Rage: An Account of Recent Researches into the Function of Emotional Excitement, Appleton, New York, 1915).

الاستتباب

He developed the concept of homeostasis from the earlier idea of Claude Bernard of milieu interieur, and popularized it in his book The Wisdom of the Body,1932. Cannon presented four tentative propositions to describe the general features of homeostasis:

1. Constancy in an open system, such as our bodies represent, requires mechanisms that act to maintain this constancy. Cannon based this proposition on insights into the ways by which steady states such as glucose concentrations, body temperature and acid-base balance were regulated.
2. Steady-state conditions require that any tendency toward change automatically meets with factors that resist change. An increase in blood sugar results in thirst as the body attempts to dilute the concentration of sugar in the extracellular fluid.
3. The regulating system that determines the homeostatic state consists of a number of cooperating mechanisms acting simultaneously or successively. Blood sugar is regulated by insulin, glucagons, and other hormones that control its release from the liver or its uptake by the tissues.
4. Homeostasis does not occur by chance, but is the result of organized self-government.

Cannon-Bard theory

Cannon developed the Cannon-Bard theory with physiologist Philip Bard to try to explain why people feel emotions first and then act upon them.

Dry mouth

He put forward the Dry Mouth Hypothesis, stating that people get thirsty because their mouth gets dry. He did an experiment on two dogs. He cut their throats and inserted a small tube. Any water swallowed would go through their mouths and out by the tube, never reaching the stomach. He found out that these dogs would lap up the same amount of water as control dogs.

= المنشورات

ألف كانون عدة كتب ومقالات.

• 1910, A Laboratory Course in Physiology
• 1911, The Mechanical Factors of Digestion
• 1915, Bodily Changes in Pain, Hunger, Fear and Rage
• 1923, Traumatic Shock
• 1932, The Wisdom of the Body
• 1936, Digestion and Health
• 1937, Autonomic Neuro-effector Systems, with Arturo Rosenblueth
• 1945, The Way of an Investigator

قراءة إضافية

• Saul Benison, A. Clifford Barger, Elin L. Wolfe (1987) Walter B. Cannon: the Life and Times of a Young Scientist, [ISBN 0-674-94580-8].
• Elin L. Wolfe, A. Clifford Barger, Saul Benison (2000) Walter B. Cannon, Science and Society, [ISBN 0-674-00251-2].
• Walter Bradford Cannon: Reflections on the Man and His Contributions, International Journal of Stress Management, Vol. 1, No. 2, 1994
• Marian Cannon Schlesinger, Snatched from Oblivion: A Cambridge Memoir, Boston: Little, Brown and Company, 1979

وصلات خارجية

• 6th APS President at the American Physiological Society
• Walter Bradford Cannon: Experimental Physiologist, a biographical article by Edric Lescouflair, dated 2003
• Chapter 9 of Explorers of the body, by Steven Lehrer (contains information about X ray experiments)
• The Walter Bradford Cannon papers can be found at The Center for the History of Medicine at the Countway Library, Harvard Medical School.

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