How the Body Works: The Mouth

The mouth is the beginning of the digestive system. It is here that the first stages of food breakdown begin. When food enters the mouth, saliva, a fluid containing the digestive enzyme ptyalin and mucus, is secreted by the salivary glands. Saliva not only lubricates the food and begins its chemical digestion, but it also helps to keep the mouth cavity moist and clean. The teeth function mechanically to break up the food into smaller, more readily swallowed and digestible pieces. The tongue and the muscular walls of the mouth shape the food into a moist ball, the bolus, which is pushed to the back of the mouth and into the pharynx to be swallowed.