The Digestive Syste5

The Digestive Syste5 - the blood when energy sources are...

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The Digestive System Carbohydrates Polysaccharides are split into disaccharides by salivary and pancreatic amylases. Disaccharides are broken down to monosaccharides by disaccharidases on the surface of the intestinal epithelium. Monosaccharides are absorbed by active transport into the blood and carried by the hepatic portal vein to the liver. Glucose is carried in the blood and enters most cells by facilitated diffusion. Insulin increases the rate of glucose transport into most cells. Lipids Bile salts emulsify lipids. Pancreatic lipase breaks down lipids. The breakdown products aggregate with bile salts to form micelles. Micelles come into contact with the intestinal epithelium, and their contents diffuse into the cells, where they are packaged and released into the lacteals. Lipids are stored in adipose tissue and in the liver, which release the lipids into
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Unformatted text preview: the blood when energy sources are needed elsewhere in the body. Proteins Proteins are split into small polypeptides by enzymes secreted by the stomach and pancreas, and on the surface of intestinal cells. Peptidases on the surface of intestinal epithelial cells complete the digestive process. Amino acids are absorbed into intestinal epithelial cells. Amino acids are actively transported into cells under the influence of growth hormone and insulin. Amino acids are used to build new proteins or as a source of energy. Water and Minerals Water can move either direction across the intestinal wall, depending on osmotic conditions. Approximately 99% of the water entering the intestine is absorbed. Most minerals are actively transported across the intestinal wall....
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