Where Does Chemical Digestion Begin?

Chemical digestion begins in the mouth. The salivary glands of the mouth secrete the enzyme amylase, which begins to break down the bonds of starch found in foods.

In the mouth, both the mechanical and chemical digestion of food occur. Mechanical digestion occurs when food is broken down into physically smaller pieces, typically through chewing. Much of the chemical digestion of food takes place elsewhere, however, the digestion of carbohydrates starts in the mouth.

Salivary amylase breaks down the bonds of starch, a polysaccharide, producing molecules of maltose, a disaccharide. Two types of amylase are present in the body. The first type acts in the mouth. The second type is more resistant than salivary amylase because it has to function within the more hostile environment of the small intestine.