Final Digestion and Absorption

1. Final Digestion and Absorption Chapter 15 Section 3

2. The Small Intestine • Small intestine: part of the digestive system where most chemical digestion takes place • 6 meters long • Name came from diameter (2-3cm wide) • Thick liquid by the time it reaches the small intestine • Begins to mix with enzymes and secretions that are produced by the small intestine, liver, and pancreas • Chemical digestion and absorption of nutrients takes place in the small intestine

3. The Liver • Liver: largest organ inside the body, which is located in the upper right part of the abdomen • Role of the liver is to produce bile • Bile: substance that breaks up fat particles, flows from liver to gallbladder • Gallbladder: organ that stores bile • Bile passes through a tube from the gallbladder into the small intestine

4. The Pancreas • Pancreas: triangular organ that lies between the stomach and the first part of the small intestine • Pancreas produces enzymes that flow into the small intestine and help break down starches, proteins, and fats • Fiber in food is not broken down, thickens liquid material in the intestine

5. Absorption in the Small Intestine • After chemical digestion takes place, the small nutrient molecules are ready to be absorbed by the body • Small intestine is well suited for absorption • Inner surface of the small intestine is bumpy • Villi: tiny finger-shaped structures that cover the inner surface of the small intestine, absorb nutrient molecules • Nutrient molecules pass from cells on the surface of a villus into blood vessels

6. The Large Intestine • Large intestine: about 1.5 meters long, contains bacteria that feed on the material passing through and make certain vitamins for the body • Functions • Water is absorbed into the bloodstream • Remaining material is prepared for elimination • Rectum: short tube that is compressed into a solid form • Anus: muscular opening through which wastes are removed from the body