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Cannon, Walter Bradford

student bismuth compound

(1871–1945) US physiologist: introduced first radio-opaque agent.

Cannon was very much a Harvard man; he was an arts student there, then a medical student, and professor of physiology from 1906–42. Discovered X-rays in 1896 and the next year Cannon, still a student, tried feeding a cat a meal containing a bismuth compound to give an X-ray ‘shadow’ of its alimentary tract. The method worked, and made the mechanics of digestion visible; and, with a barium compound in place of bismuth, it has been used in diagnostic radiography ever since. Cannon went on to work on the effect of shock and emotion on the nervous system and the transmission of nerve impulses. He developed concept of the importance of a constant internal physiological environment (ie a narrow range of salt, sugar, oxygen and temperature in the living body) which he named homeostasis, and he studied the mechanism which achieves this essential equilibrium. Later he applied similar ideas to political and social organizations, but without the same success.

Cantelli, Guido [next] [back] Cannon, Reuben (1946–)

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