Principles of Biochemistry

The interior surface of the small intestine is composed of micro villi that dramatically enlarge its absorptive surface, accounting for an extraordinary efficiency in absorbing consumed energy substrates. 98 percent of all digestible carbohydrate is absorbed. The digestion of food polysaccharides, such as starch, sucrose and lactose produces the monosaccharides glucose, fructose, and galactose, which pass into the blood stream. Galactose and fructose are converted to glucose in the liver. The liver stores the glucose as glycogen and releases glucose as and when needed to maintain blood glucose level.