Russell Elder, age 12, of Barre, Vt., for his question:

HOW IS SALIVA PRODUCED?

Saliva is a sticky fluid produced in the mouth. Three pairs of glands in the mouth and cheeks, known as salivary glands, produce the saliva. One pair, the parotid, is located in front of the ears. Another pair, the submandibular, is located under the lower jaw. The third pair is located under the tongue and is known as the sublingual.

There are several other small glands in the mucous membrane of the mouth that aid in producing saliva.

Saliva is important to the digestion of food. It has a colorless and watery appearance. It contains some mucus and produces an alkaline or acid neutralizing chemical action. Saliva contains an enzyme called ptyalin that changes starches into simpler substances called maltose.

Saliva moistens and softens all food that is taken into the mouth. It helps in the chewing and swallowing of food. It also keeps the mouth moist, which is important to comfort.

Saliva's most important action is on starchy foods. Saliva breaks down all starches into maltose, the first step in digestion.