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Lesson 6.1 Digestion Red Book: 162-169 (reference) 1 Large food molecules are polymers, which must be broken down into monomers (via hydrolysis) in order to be absorbed into the blood. 2 Enzymes speed up the rate at which polymers are broken down into monomers. 3 Amylase Protease Lipase Example of this enzyme Salivary amylase Pepsin Pancreatic lipase Source Salivary glands Wall of stomach Pancreas Substrate Starch Proteins Triglycerides (fats and oils) Product Maltose Small polypeptides Fatty acids and glycerol Optimum pH 7-8 1.5-3 7-8 4 Locate: mouth, esophagus, stomach, small intestine, large intestine, anus, liver, pancreas, gall bladder. Peristalisis: the movement of food through the digestive tract. 5 Stomach- primary site for protein digestion. Small intestine- primary site for nutrient absorption. Epithelial layer is 1 cell thick. Large intestine- water used in the digestive process is reabsorbed back into the body. 6 Absorption- the transfer of nutrients from the digestive tract into the blood stream, usually through villi in the small intestine. Assimilation- uptake of nutrients from blood stream into body tissue. Occurs after absorption. 7 Pictured: microvilli on a villus. Villi have a large surface area, gated ion channels, and are dense in mitochondria, which provide energy for the active transport of nutrients. 8 The Digestive System