Claude Bernard | French Physiologist, Experimentalist & Philosopher

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border-right-sm border-left-sm open"> <div class="drawer d-flex flex-column open"> <div class="left-rail-section-content"> <div class="topic-left-rail-header text-truncate bg-gray-50 position-relative text-right d-flex align-items-center"> <div class="tlr-title px-20 py-15 text-left"> <em class="material-icons text-gray-400 d-lg-none" data-icon="toc"></em> <a class="font-serif font-weight-bold text-black link-blue" href="https://www.britannica.com/biography/Claude-Bernard">Claude Bernard</a> </div> <button aria-label="Close" class="js-sections-close-button btn-link btn-sm btn d-lg-none position-absolute top-0 p-10 right-0" > <em class="material-icons font-26" data-icon="close"></em> </button> </div> <div class="section-content pl-10 pr-20 pl-sm-50 pr-sm-60 pl-lg-5 pr-lg-10 pt-10 pt-lg-0 bg-gray-50 clear-catfish-ad"> <div class="toc mb-20"> <div class="font-serif font-14 font-weight-bold mx-15 mb-15 mt-20"> Table of Contents </div> <ul class="list-unstyled my-0" data-level="h1"><li data-target="#ref1"><div class="pl-25"><a class="link-gray-900 w-100" href="/biography/Claude-Bernard">Introduction</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref8214"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/biography/Claude-Bernard#ref8214">Early training.</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref8215"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/biography/Claude-Bernard#ref8215">Research on the pancreas and the liver.</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref8216"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/biography/Claude-Bernard/Recognition-and-later-work">Recognition and later work.</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li></ul> <a class="toc-extra-link link-gray-900" href="/quotes/Claude-Bernard">Quotes</a> <a class="toc-extra-link link-gray-900" href="https://www.britannica.com/biography/Claude-Bernard/additional-info">References & Edit History</a> <a class="toc-extra-link link-gray-900" href="/facts/Claude-Bernard">Quick Facts & Related Topics</a> </div> <div class="tlr-media-slider pb-10 mb-30"> <a class="section-header link-gray-900 font-serif font-14 font-weight-bold mb-10 mx-10" href="https://www.britannica.com/biography/Claude-Bernard/images-videos">Images</a> <div class="slider js-slider position-relative d-inline-flex align-items-center mw-100 "> <div class="slider-container js-slider-container overflow-hidden d-flex overflow-hidden text-nowrap ml-15"> <a href="https://cdn.britannica.com/95/29895-004-D38C8758/Claude-Bernard-detail-lithograph-A-Laemlein-1858.jpg" data-href="/media/1/62382/22469" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/95/29895-004-D38C8758/Claude-Bernard-detail-lithograph-A-Laemlein-1858.jpg" alt="Claude Bernard, detail of a lithograph by A. Laemlein, 1858" height="50" /> </a> <a href="https://cdn.britannica.com/17/144217-050-EFE58E53/Claude-Bernard-French-role-function-digestion-pancreas.jpg" data-href="/media/1/62382/149165" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/17/144217-004-3B877FB7/Claude-Bernard-French-role-function-digestion-pancreas.jpg" alt="Bernard, Claude" height="50" /> </a> <a href="https://cdn.britannica.com/18/144218-050-F0E52B93/Claude-Bernard-illustration-statue.jpg" data-href="/media/1/62382/149166" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/18/144218-004-46D49613/Claude-Bernard-illustration-statue.jpg" alt="Bernard, Claude" height="50" /> </a> </div> <button disabled class="prev-button js-prev-button position-absolute btn btn-circle shadow btn-blue " aria-label="Previous"> <span class="material-icons md-24" data-icon="keyboard_arrow_left"></span> </button> <button disabled 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Please refer to the appropriate style manual or other sources if you have any questions. </div> <div class="label mt-20 mb-10">Select Citation Style</div> <select class="js-citation-format-select form-select"> <option selected value="mla">MLA</option> <option value="apa">APA</option> <option value="chicago">Chicago Manual of Style</option> </select> <div class="citation font-serif border rounded p-15 mt-20" data-authors="Virtanen, Reino" data-authors-initial="Virtanen, R." data-title="Claude Bernard" data-published-date="6 Feb. 2025" data-url="https://www.britannica.com/biography/Claude-Bernard" > <div class="citation-text"></div> </div> <button class="js-copy-citation-button mt-20 btn btn-xs btn-outline-blue border shadow-sm pr-10" > <em class="material-icons md-icon ml-n10 my-n5 mr-5" data-icon="file_copy"></em> <span class="js-citation-status-text">Copy Citation</span> </button> </div> </div> </div> <div> <button class="js-share-modal-button js-modal btn btn-sm btn-link gtm-topic-tool font-weight-bold btn-link" data-modal="[data-topic-id=62382] .md-share-modal"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="share"></em> Share </button> <div class="md-share-modal size-lg d-none qa-share-modal"> <div class="md-modal-body"> <div class="h2 font-serif d-flex align-items-center pb-15 border-bottom"> <em class="material-icons text-blue mr-10" data-icon="share"></em> Share </div> <div class="label my-20">Share to social media</div> <div class="md-social-toolbar-circle d-flex align-items-start inverted" data-value="share" title="Claude Bernard" data-url="https://www.britannica.com/biography/Claude-Bernard" > <a class="social-icon facebook justify-content-center d-flex align-items-center align-self-center" data-provider="facebook" href="https://www.facebook.com/BRITANNICA/" target="_blank" rel="noopener"><span>Facebook</span></a> <a class="social-icon x justify-content-center d-flex align-items-center align-self-center" data-provider="x" href="https://x.com/britannica" target="_blank" rel="noopener"><span>X</span></a> </div> <div class="label pt-20 mt-20 mb-5 border-top">URL</div> <a class="font-serif text-truncate d-inline-block" href="https://www.britannica.com/biography/Claude-Bernard">https://www.britannica.com/biography/Claude-Bernard</a> </div> </div> </div> <div> <button class="js-feedback-modal-button js-modal btn btn-sm btn-link gtm-topic-tool font-weight-bold btn-link" data-modal=".md-feedback-modal"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="message"></em> Feedback </button> </div> <div> <button class="qa-external-website-modal-button js-modal btn btn-sm btn-link gtm-topic-tool font-weight-bold btn-link" data-modal="[data-topic-id=62382] .md-websites-modal"> <em class="material-icons md-icon ml-n10 mr-5" data-icon="link"></em> External Websites </button> </div> </div> <div class="md-feedback-modal size-lg d-none"> <div class="md-modal-body"> <div class="h2 font-serif pb-15 border-bottom"> Feedback </div> <form method="post" action="/submission/feedback/62382"> <div class="my-20"> Corrections? 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Author of <i>Claude Bernard and His Place in the History of Ideas.</i></div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> Reino Virtanen</span></div> <div class="font-serif font-12 text-gray-700"> <span class="qa-fact-checked-by">Fact-checked by</span> <div class="editor-popover popover p-0"> <a class="d-block p-20 qa-editor-popup font-12" href="/editor/The-Editors-of-Encyclopaedia-Britannica/4419" > <div class="editor-title font-16 font-weight-bold">The Editors of Encyclopaedia Britannica</div> <div class="editor-description font-12 font-serif mt-5 text-black">Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link font-12 "> The Editors of Encyclopaedia Britannica</span></div> <div class="last-updated font-12 font-serif"> <span class="text-gray-700"> Last Updated: <time datetime="2025-02-06T00:00:00CST" >Feb 6, 2025</time> •</span> <a class="byline-edit-history" href="https://www.britannica.com/biography/Claude-Bernard/additional-info#history" rel="nofollow">Article History</a> </div></div> </div> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button d-none d-sm-block js-sections-inline-button module-spacing btn d-lg-none"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <div class="d-flex d-sm-none flex-row"> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button js-sections-inline-button module-spacing"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <button class="ai-ask-button btn btn-sm border-2 btn-outline-red-400 border-red-400 module-spacing js-inline-ai-ask-button p-10 ml-5"> Ask the Chatbot </button> </div> <div class="js-qf-module qf-module px-40 px-sm-20 py-15 mx-auto module-spacing font-14 bg-gray-50 rounded"> <div class="qf-title font-weight-bold font-14 mb-10 text-center"> Quick Facts</div> <div class="facts-list mt-10"> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Born: </dt> <dd>July 12, 1813, Saint-Julien, <a href="/place/France">France</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Died: </dt> <dd> Feb. 10, 1878, <a href="/place/Paris">Paris</a> (aged 64)</dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Awards And Honors: </dt> <dd><a href="/science/Copley-Medal">Copley Medal (1876)</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Notable Works: </dt> <dd><a href="/topic/An-Introduction-to-the-Study-of-Experimental-Medicine">“An Introduction to the Study of Experimental Medicine”</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Subjects Of Study: </dt> <dd><a href="/science/blood-biochemistry">blood</a></dd> <dd><a href="/science/circulation-anatomy-and-physiology">circulation</a></dd> <dd><a href="/science/curare">curare</a></dd> <dd><a href="/science/digestion-biology">digestion</a></dd> <dd><a href="/science/experimentation-science">experimentation</a></dd> <dd><a href="/science/glycogen">glycogen</a></dd> <dd><a href="/science/liver">liver</a></dd> <dd><a href="/science/medicine">medicine</a></dd> <dd><a href="/science/milieu-interieur">milieu intérieur</a></dd> <dd><a href="/science/pancreas">pancreas</a></dd> <dd><a href="/science/secretion">secretion</a></dd> <dd><a href="/science/vasomotor-system">vasomotor system</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> <div class="text-center"> <a class="btn btn-sm btn-link p-0" href="/facts/Claude-Bernard"> See all related content </a> </div> </div> </div> </div><span class="marker before-article"></span><section data-level="1" id="ref1"><span class="marker PREMOD1 mod-inline"></span><p class="topic-paragraph"><strong><span id="ref35117"></span>Claude Bernard</strong> (born July 12, 1813, Saint-Julien, France—died Feb. 10, 1878, Paris) was a French physiologist known chiefly for his discoveries concerning the role of the pancreas in <a href="https://www.britannica.com/science/digestion-biology" class="md-crosslink autoxref " data-show-preview="true">digestion</a>, the glycogenic function of the liver, and the regulation of the <a href="https://www.britannica.com/science/blood-biochemistry" class="md-crosslink autoxref " data-show-preview="true">blood</a> supply by the vasomotor nerves. On a broader stage, Bernard played a role in establishing the principles of experimentation in the life sciences, advancing beyond the vitalism and indeterminism of earlier <span id="ref35118"></span><a href="https://www.britannica.com/science/physiology" class="md-crosslink " data-show-preview="true">physiologists</a> to become one of the founders of experimental <span id="ref35119"></span><a href="https://www.britannica.com/science/history-of-medicine" class="md-crosslink " data-show-preview="true">medicine</a>. His most <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="seminal" href="https://www.merriam-webster.com/dictionary/seminal" data-type="MW">seminal</a> contribution was his concept of the internal <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="environment" href="https://www.merriam-webster.com/dictionary/environment" data-type="MW">environment</a> of the organism, which led to the present understanding of <span id="ref35120"></span><a href="https://www.britannica.com/science/homeostasis" class="md-crosslink " data-show-preview="true">homeostasis</a>—<em>i.e.,</em> the self-regulation of vital processes.</p><span class="marker MOD1 mod-inline"></span></section> <span class="marker h2"></span><section data-level="1" id="ref8214"><h2 class="h1">Early training.</h2> <span class="marker PREMOD2 mod-inline"></span><p class="topic-paragraph">Bernard’s father, Pierre, was a winegrower; his mother, Jeanne Saulnier, was of peasant background. When Claude was very young, his father failed in a wine-marketing venture and tried to make ends meet by teaching school. Despite his efforts, the family never prospered, and when he died, the survivors were left in debt. Educational opportunities were scarce for a poor winegrower’s son in the <a href="https://www.britannica.com/place/France" class="md-crosslink autoxref " data-show-preview="true">France</a> of <a href="https://www.britannica.com/biography/Louis-XVIII" class="md-crosslink autoxref " data-show-preview="true">Louis XVIII</a>. The boy studied Latin with the local priest and then was enrolled in a Jesuit-conducted school at Villefranche, where no natural <a href="https://www.britannica.com/science/science" class="md-crosslink autoxref " data-show-preview="true">science</a> was taught. At 18 Bernard ended his secondary schooling at Thoissey without a diploma and was apprenticed to an <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="apothecary" href="https://www.britannica.com/dictionary/apothecary" data-type="EB">apothecary</a> in a <a href="https://www.britannica.com/place/Lyon-France" class="md-crosslink autoxref " data-show-preview="true">Lyon</a> suburb.</p><span class="marker MOD2 mod-inline"></span> <span class="marker PREMOD3 mod-inline"></span><p class="topic-paragraph">Bernard’s days were spent in menial tasks relieved by errands to a veterinary school or, on his rare times off, by visits to a theatre. He wrote a playlet, <em>La Rose du Rhône,</em> now lost, and then began writing <em>Arthur de Bretagne,</em> a historical drama in five acts. His employer was not pleased, however, and the apprenticeship came to a halt, the youth returning home in July 1833. By November 1834 he was in <a href="https://www.britannica.com/place/Paris" class="md-crosslink autoxref " data-show-preview="true">Paris</a> with the completed manuscript of <em>Arthur de Bretagne</em> and a letter of introduction. The literary critic Saint-Marc Girardin read his play and advised him to try medicine instead of playwriting.</p><span class="marker MOD3 mod-inline"></span> <span class="marker PREMOD4 mod-inline"></span><p class="topic-paragraph">Bernard enrolled that same winter in the <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="Faculty" href="https://www.britannica.com/dictionary/Faculty" data-type="EB">Faculty</a> of Medicine in Paris and, in due course, was admitted as an extern in the hospitals. Outwardly reserved and even shy at that time, he had an inner strength that was to overcome poverty and discouragements. Of 29 students passing the examination for the internship, Bernard ranked 26th. Serving in Paris hospitals were the celebrated doctors Pierre Rayer and <span id="ref35121"></span><a href="https://www.britannica.com/biography/Francois-Magendie" class="md-crosslink " data-show-preview="true">François Magendie</a>, and Bernard studied under the latter at both the Hôtel-Dieu and the <a href="https://www.britannica.com/topic/College-de-France" class="md-crosslink autoxref " data-show-preview="true">Collège de France</a>. Magendie noticed Bernard’s skillful dissections and took him on as a research assistant.</p><span class="marker MOD4 mod-inline"></span> <span class="marker PREMOD5 mod-inline"></span><p class="topic-paragraph">Bernard became involved in Magendie’s research on spinal nerves. His first publication dealt with the chorda tympani (a branch of the facial nerve), while his medical dissertation was devoted to the function of the gastric juice in nutrition (1843). These maiden publications were prophetic, for much of his later research concerned neurology and metabolism. Failing in the examination that would have qualified him to teach in the medical school, he <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="collaborated" href="https://www.merriam-webster.com/dictionary/collaborated" data-type="MW">collaborated</a> with others in research on digestion and on the exotic poison curare, thus treading two paths that would lead him to fame. He was rather old at the age of 31 to be content with a research assistantship, however, and resigned the position late in 1844. Left in financial straits, he turned his thoughts again toward medical practice.</p><a class="link-module shadow-sm d-block qa-quiz-module" href="/quiz/faces-of-science" data-link-module-iframe-link=""> <img loading="lazy" src="https://cdn.britannica.com/88/144788-131-ADACA20E/Michael-Faraday-John-Frederic-Daniell.jpg" alt="Michael Faraday (L) English physicist and chemist (electromagnetism) and John Frederic Daniell (R) British chemist and meteorologist who invented the Daniell cell." class="rounded-sm mr-15" width="70" /> <div class="line-clamp clamp-5"> <div class="module-title bg-green">Britannica Quiz</div> <div class="font-weight-semi-bold mt-5">Faces of Science</div> </div> </a><span class="marker MOD5 mod-inline"></span> <span class="marker PREMOD6 mod-inline"></span><p class="topic-paragraph">To save his research career, a friend arranged a marriage of convenience for him with Marie-Françoise Martin, daughter of a Paris doctor. The marriage brought him a dowry of 60,000 francs but was destined to be painfully unhappy. Their separation was to follow his election to the <a href="https://www.britannica.com/topic/French-Academy" class="md-crosslink autoxref " data-show-preview="true">French Academy</a> late in life.</p><span class="marker MOD6 mod-inline"></span></section> <span class="marker h3"></span><section data-level="1" id="ref8215"><h2 class="h1">Research on the pancreas and the liver.</h2> <span class="marker PREMOD7 mod-inline"></span><p class="topic-paragraph">In 1847 Bernard became Magendie’s deputy at the Collège de France. This period was marked by a veritable explosion of discoveries, beginning in 1846, when Bernard solved the mystery of the carnivorous rabbits. Puzzled one day by the chance observation that some rabbits were passing clear—not cloudy—urine, just like meat-eating animals, he inferred that they had not been fed and were subsisting on their own tissues. He confirmed his <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="hypothesis" href="https://www.merriam-webster.com/dictionary/hypothesis" data-type="MW">hypothesis</a> by feeding meat to the famished animals. An autopsy of the rabbits yielded an important discovery concerning the role of the <span id="ref35122"></span><a href="https://www.britannica.com/science/pancreas" class="md-crosslink " data-show-preview="true">pancreas</a> in <span id="ref35123"></span><a href="https://www.britannica.com/science/digestion-biology" class="md-crosslink " data-show-preview="true">digestion:</a> the secretions of the pancreas broke down fat molecules into fatty acids and glycerin. Bernard then showed that the principal processes of digestion take place in the <a href="https://www.britannica.com/science/small-intestine" class="md-crosslink autoxref " data-show-preview="true">small intestine</a>, not in the stomach as was previously believed.</p><div class="module-spacing"> <DIV class="marketing-INLINE_SUBSCRIPTION marketing-content" data-marketing-id="INLINE_SUBSCRIPTION"><style> .student-promo-banner-wrapper { container-type: inline-size; margin-bottom: 15px; } @container (min-width: 475px) { .student-promo-banner { flex-direction: row; } .student-promo-banner-img-wrapper { margin-bottom: 0; margin-right: 10px; justify-content: flex-start; } .student-promo-banner-text-wrapper { text-align: left; margin-bottom: 0px; margin-left: 10px; } .student-promo-banner-button-wrapper { margin-right: 0; } }</style> <div class="student-promo-banner-wrapper"> <div class="student-promo-banner d-flex flex-column align-items-center bg-blue rounded p-20"> <div class="student-promo-banner-img-wrapper mb-20 mr-0 d-flex justify-content-center"> <img class="rounded" style="max-width: 100px; min-width: 80px" src="https://cdn.britannica.com/marketing/BlueThistle.webp" /> </div> <div class="student-promo-banner-text-wrapper ml-0 mb-10 text-center text-white"> <div class="h2 mb-10">Get Unlimited Access</div> <div class="h4 font-weight-semi-bold">Try Britannica Premium for free and discover more.</div> </div> <div class="student-promo-banner-button-wrapper d-flex justify-content-center align-items-center ml-auto mr-auto"> <a class="btn btn-m btn-orange" href="https://premium.britannica.com/premium-membership/?utm_source=premium&utm_medium=inline-cta&utm_campaign=august-2024">Subscribe</a> </div> </div> </div> </DIV></div><span class="marker MOD7 mod-inline"></span> <span class="marker PREMOD8 mod-inline"></span><p class="topic-paragraph">His work on the pancreas led to research on the <span id="ref35124"></span><a href="https://www.britannica.com/science/liver" class="md-crosslink " data-show-preview="true">liver</a>, culminating in his second great discovery, the <span id="ref35125"></span><a href="https://www.britannica.com/science/glycogen" class="md-crosslink " data-show-preview="true">glycogenic</a> function of the liver. In 1856 Bernard discovered <a href="https://www.britannica.com/science/glycogen" class="md-crosslink autoxref " data-show-preview="true">glycogen</a>, a white starchy substance found in the liver. He found that this complex substance was built up by the body from sugar and served as a storage reserve of carbohydrates that could be broken down to sugars as needed, thereby keeping the sugar content of the blood at a constant level. Bernard’s discovery showed that the digestive system not only breaks down complex molecules into simple ones but also does the opposite, building up complex molecules from simpler ones. Simultaneously, he was nearing his third great achievement—explanation of the regulation of the blood supply by the <span id="ref35126"></span>vasomotor nerves. He discovered in this regard that the vasomotor nerves control the dilation and constriction of blood vessels in response to temperature changes in the environment. For example, in cold weather the blood vessels of the skin constrict in order to conserve heat, while in hot weather they expand to dissipate excess heat. This control mechanism, like the glycogenic functions of the liver, illustrates how the body maintains a stable internal environment in the midst of changing external conditions—a fundamental phenomenon known as <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="homeostasis" href="https://www.merriam-webster.com/dictionary/homeostasis" data-type="MW">homeostasis</a>.</p><div class="one-good-fact-module"> </div><span class="marker MOD8 mod-inline"></span> <span class="marker PREMOD9 mod-inline"></span><p class="topic-paragraph">Bernard also conducted important studies on the effects of such poisons as <span id="ref35127"></span><a href="https://www.britannica.com/science/carbon-monoxide-poisoning" class="md-crosslink " data-show-preview="true">carbon monoxide</a> and <span id="ref35128"></span><a href="https://www.britannica.com/science/curare" class="md-crosslink " data-show-preview="true">curare</a> on the body. He showed that <a href="https://www.britannica.com/science/carbon-monoxide" class="md-crosslink autoxref " data-show-preview="true">carbon monoxide</a> could substitute for oxygen and combine with hemoglobin, thereby causing oxygen starvation. His experiments with curare showed how this dread poison causes paralysis and death by attacking the motor nerves, while having no effect on the sensory nerves. He demonstrated that, because of this selectivity, curare could be used as an experimental tool in <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="differentiating" href="https://www.merriam-webster.com/dictionary/differentiating" data-type="MW">differentiating</a> neuromuscular from primary muscular mechanisms.</p><span class="marker MOD9 mod-inline"></span></section> <span class="marker end-of-content"></span><span class="marker after-article"></span></div> <div id="chatbot-simplify-root"></div> <div id="chatbot-root"></div> </div> </div> </div> <div class="ai-dialog-placeholder"></div> </div> </div> <aside class="col-md-da-320"></aside> </div> </div> </div> </div> </article> </div> </div> </div> </div> </main> <div id="md-footer"></div> <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-5W6NC8" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <script type="text/javascript" id="_informizely_script_tag"> var IzWidget = IzWidget || {}; (function (d) { var scriptElement = d.createElement('script'); scriptElement.type = 'text/javascript'; scriptElement.async = true; scriptElement.src = "https://insitez.blob.core.windows.net/site/f780f33e-a610-4ac2-af81-3eb184037547.js"; var node = d.getElementById('_informizely_script_tag'); node.parentNode.insertBefore(scriptElement, node); } )(document); </script>  <script> window.ap3c = window.ap3c || {}; var ap3c = window.ap3c; ap3c.cmd = ap3c.cmd || []; ap3c.cmd.push(function() { ap3c.init('ZO4siT4cLwnykPnzZWJtd3Byb2Q', 'https://engage.email.britannica.com/'); ap3c.track({v: 0}); }); ap3c.activity = function(act) { ap3c.act = (ap3c.act || []); ap3c.act.push(act); }; var s, t; s = document.createElement('script'); s.type = 'text/javascript'; s.src = "https://engage.email.britannica.com/app.js"; t = document.getElementsByTagName('script')[0]; t.parentNode.insertBefore(s, t); </script> <script class="marketing-page-info" type="application/json"> {"pageType":"Topic","templateName":"DESKTOP","pageNumber":1,"pagesTotal":2,"pageId":62382,"pageLength":1052,"initialLoad":true,"lastPageOfScroll":false} </script> <script class="marketing-content-info" type="application/json"> [] </script> <script src="https://cdn.britannica.com/mendel-resources/3-133/js/libs/jquery-3.5.0.min.js?v=3.133.36"></script> <script type="text/javascript" data-type="Init Mendel Code Splitting"> (function() { $.ajax({ dataType: 'script', cache: true, url: 'https://cdn.britannica.com/mendel-resources/3-133/dist/topic-page.js?v=3.133.36' }); })(); </script> <script class="analytics-metadata" type="application/json"> {"leg":"D","adLeg":"C","userType":"ANONYMOUS","pageType":"Topic","pageSubtype":null,"articleTemplateType":"BIO_PAGINATED","gisted":false,"pageNumber":1,"hasSummarizeButton":false,"hasAskButton":true} </script> <script type="text/javascript"> EBStat={accountId:-1,hostnameOverride:'webstats.eb.com',domain:'www.britannica.com', json:''}; </script> <script type="text/javascript"> ( function() { $.ajax( { dataType: 'script', cache: true, url: '//www.britannica.com/webstats/mendelstats.js?v=1' } ) .done( function() { try {writeStat(null,EBStat);} catch(err){} } ); })(); </script> <div id="bc-fixed-dialogue"></div> </body> </html>

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Claude Bernard | French Physiologist, Experimentalist & Philosopher | Britannica