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Digestive System

Learn about the digestive system and how it breaks down food into simple forms that can be absorbed by cells. Discover the fascinating story of Alexis St. Martin and Dr. William Beaumont, who conducted experiments on digestion. Explore key terms like bolus, chyme, absorption, and villi.

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Digestive System

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  1. Digestive System

  2. Digestion—the process where food is broken into simple forms the cells can use.

  3. 2 Main Functions of Digestion • Break down food • Absorb food

  4. Alexis St. Martin and Dr. William Beaumont—cool story • St. Martin "was accidentally wounded by a discharge from a musket. Through an orifice, large enough to admit a fore-finger, oozed the remnants of the food he had eaten for breakfast.

  5. DESCRIPTION OF WOUND: The hole in St. Martin's side was a permanent open gastric fistula, large enough that Beaumont could insert his entire forefinger into the stomach cavity.

  6. On August 7, 1825, Beaumont had St. Martin fast for 17 hours, and then took the temperature of St. Martin's stomach (it was 100 degrees) • Beaumont removed gastric juice from St. Martin's stomach, then observed the rate of digestion of a piece of corned boiled beef "test-tube" style, while also placing the same-sized piece of • meat directly into St. • Martin's stomach.

  7. The stomach digested the meat in two hours; the vial of gastric juice took 10 hours (maintained at about 100 degrees). • The next day, Beaumont repeated the experiments using boiled chicken, which he found digested slower than the beef. • The experiments showed that gastric juice has solvent properties.

  8. In September, St. Martin returned home to Canada (where he married and had children), so Beaumont was unable to experiment on him further at this time.

  9. Other words to digest: • Bolus—Peristalsis pushes the bolus of food down the esophagus. • Chyme—the solid food you eat is turned into this creamy liquid • in the stomach.

  10. Absorption—the process of taking into the bloodstream by osmosis. • Villi—millions of tiny fingerlike structures that cover the surface of the small intestine to aid in absorption.

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