The salivary |glands| (along with other |mucous membranes| in the |mouth| cavity) are responsible for secreting saliva, a clear, alkaline, semi-viscous liquid which helps in the digestion of food. The salivary |glands| include the large |parotid gland| and the smaller submaxillary and |sublingual glands|. When food is smelled or tasted, or often even thought of, the salivary |glands| begin their secretion to prepare the |mouth| for the food. Salivation at the thought or sense of food is one example of a Pavlovian response, named after the scientist which investigated such ~reflexes~ in dogs. ~Mumps~, an inflammatory glandular ~infection~, affects the salivary |glands| (in addition to others), resulting in difficulty chewing and swallowing. Saliva also performs a cleaning function, serving to keep exfoliated epithelial cells, most bacteria, and food particles away from the |teeth|. Saliva keeps the |mouth| lubricated for articulation and speech and also helps to moisten food to assist in swallowing. ~Enzymes~ in saliva begin digestive breakdown of the food even before it reaches the |stomach|. A number of toxins (including lead, mercury, and other heavy metals) are secreted in the saliva and the body's water balance regulation is also assisted by salivary secretion.