Claude Bernard

John Gehl sends this bio of the French physiologist Claude Bernard (1813-1878), who is considered the founder of experimental physiology and experimental pharmacology. Bernard believed that the body has mechanisms by which it seeks to maintain a stable internal environment despite changes in the external environment. In 1851, Bernard discovered that the nervous system, in response to internal cold, sends messages to the blood vessels to constrict in order to conserve body heat. Bernard found that most absorption and some digestion take place in the small intestine, that secretions of the pancreas play a role in fat digestion, and that the liver has an important glycogenic function. He also showed how the drug curare works in the body to produce its effect. He is the author of the science classic, Introduction to the Study of Experimental Medicine published in 1865.

Bernard was the son of poor vineyard workers and he never lost his fondness for country life, returning home every fall to participate in the grape harvest in the Beaujolais vineyards. His early schooling took place in church schools, and at 19 he apprenticed himself to an apothecary, expecting to spend his spare time writing for the stage. When a friendly critic of his early plays suggested he abandon writing for another professional career, he decided to study medicine. He struggled through medical school, just barely meeting the requirements for a medical degree in 1843. Instead of becoming a practicing physician, he went to work as assistant to the famous physiologist Dr. Francois Magendie from whom he learned the rudiments of experimental medicine. Bernard proved himself to be an apt pupil, skilled in the vivisection of small animals and carrying out systematic experimental investigations of physiological processes, beginning with the study of digestion.

Bernard discovered that the liver converts sugar to glycogen, the animal starch substance used to maintain blood sugar levels. He also found that juices of the pancreas help digest and absorb fats. He discovered how the nervous system controls blood circulation, and he carried out research on how drugs and poisons affect the body. His approach to research was essentially modern; he combined experimental skill with theory and had a valuable talent for noting experimental results that were not in accord with existing ideas, which led to fruitful new concepts. Perhaps his greatest contribution to physiology was the idea that life is dependent on a constant internal environment (homeostasis), noting that cells function best within a narrow range of osmotic pressure and temperature and bathed in a fairly constant concentration of chemical constituents such as sugars and metallic ions. Later in his career, Bernard focused on methods of research, becoming something of a philosopher of medical science, promoting the critical importance of medical research based on experimental investigations. By the time of his death in 1870 from kidney disease, Bernard had risen to such eminence that the French government gave him a state sponsored public funeral, the first ever scientist accorded this honor.


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Ronald Hilton 2004


last updated: October 8, 2004