Describe the digestion, absorption, and elimination of carbohydrates.
Simple sugars (monosaccharides) are soluble in water. They can be absorbed in the intestine without further change, and consequently are not digested. Disaccharides and polysaccharides are hydrolyzed during digestion into two simple sugars and many simple sugars respectively. One molecule of a disaccharide when hydrolyzed with one molecule of water in the presence of an appropriate enzyme, gives two monosaccharides. When polysaccharides are hydrolyzed, they break up into many simple sugars. The chemical digestion of carbohydrates occurs in the presence of different enzymes known as glycosidases. Enzymes secreted by the small intestine continue the process: maltase hydrolyzes maltose to glucose, invertase acts upon sucrose and hydrolyzes it to glucose and fructose.