salivaArticle Free Pass saliva, a thick, colourless, opalescent
fluid that is constantly present in the mouth of humans and
other vertebrates. It is composed of water, mucus, proteins,
mineral salts, and amylase. As saliva circulates in the mouth
cavity it picks up food debris, bacterial cells, and white blood
cells. One to two litres of fluid are excreted daily into the
human mouth. Three major pairs of salivary glands and many
smaller glands scattered in the surface tissue of the cheeks,
lips, tongue, and palate contribute to the total amount of
saliva. Small amounts of saliva are continually being secreted
into the mouth, but the presence of food, or even the mere smell
or thought of it, will rapidly increase saliva flow. The
functions of saliva are numerous. Primarily, it lubricates and
moistens the inside of the mouth to help with speech and to
change food into a liquid or semisolid mass that can be tasted
and swallowed more easily. Saliva helps to control the body’s
water balance; if water is lacking, t