Additionally, enzymes are secreted by the intestinal cells that line the villi. This pancreatic juice contains the enzyme, pancreatic amylase, which starts again the breakdown of dextrins into shorter and shorter carbohydrate chains. Upon entry of the chyme into the small intestine, the pancreas releases pancreatic juice through a duct. The chyme is gradually expelled into the upper part of the small intestine. But mechanical breakdown is ongoing-the strong peristaltic contractions of the stomach mix the carbohydrates into the more uniform mixture of chyme.įigure 4.6 Salivary Glands in the Mouth Salivary glands secrete salivary amylase, which begins the chemical breakdown of carbohydrates by breaking the bonds between monomeric sugar units. (This is a good thing as more glucose in the mouth would lead to more tooth decay.) When carbohydrates reach the stomach no further chemical breakdown occurs because the amylase enzyme does not function in the acidic conditions of the stomach. Only about five percent of starches are broken down in the mouth. The increased concentration of maltose in the mouth that results from the mechanical and chemical breakdown of starches in whole grains is what enhances their sweetness. The salivary amylase breaks down amylose and amylopectin into smaller chains of glucose, called dextrins and maltose. This enzyme breaks the bonds between the monomeric sugar units of disaccharides, oligosaccharides, and starches. Saliva contains the enzyme, salivary amylase.
The salivary glands in the oral cavity secrete saliva that coats the food particles. Chewing, also known as mastication, crumbles the carbohydrate foods into smaller and smaller pieces.
The mechanical and chemical digestion of carbohydrates begins in the mouth.
Digestion and Absorption of Carbohydrates From the Mouth to the Stomach