Why does salivary amylase stop working when it reaches the stomach?
Amylase is also secreted from the pancreas, therefore carbohydrate digestion resumes in the small intestine. Membrane bound enzymes such as lactase on the brush border membrane of the epithelial cells lining the small intestine breakdown disaccharides into monosaccharides. Monosaccharides are then absorbed from the small intestine. Protein digestion starts in the stomach where pepsin breaks down proteins into peptides. Protein digestion continues in the small intestine with the pancreas secreting trypsin which also breaks down proteins into peptides. Peptidases secreted by the pancreas and present on the brush border membrane of the epithelial cells lining the small intestine catalyze the breakdown of peptides into amino acids. Amino acids are then absorbed from the small intestine. Lipid digestion does not begin until the small intestine. In the small intestine bile is secreted from the gall bladder. Bile salts emulsify the dietary lipids forming smaller fat droplets so that lipase se
