[L. saliva, spittle]
The fluid secretion of the salivary gland and oral mucous gland that begins the process of digesting food. Saliva moistens food for tasting, chewing, and swallowing; initiates digestion of starches; moistens and lubricates the mouth; and acts as a solvent for excretion of waste products.
SYN: SEE: spit (1); SEE: spittle
It is normally tasteless, clear, odorless, viscid, and weakly alkaline, being neutralized after being acted on by gastric acid in the stomach. Its specific gravity is 1.002 to 1.006. The amount secreted in 24 hr is estimated to be 1500 ml. The flow varies from 0.2 ml/min from resting glands to 4.0 ml/min with maximum secretion.
Saliva is 99.5% water. Inorganic constituents include salts (chlorides, carbonates, phosphates, sulfates) and dissolved gases. Organic constituents include enzymes (amylase and lysozyme), proteins (mucin, albumin, and globulins), small amounts of urea, and unusual waste products, e.g., acetone. Epithelial cells and leukocytes are also present.
Saliva is readily accessible and easy to transport and store and has become useful for clinical laboratory testing. In the year 2000, U.S. Food and Drug Administration-approved diagnostic tests on saliva include assays for antibodies to HIV, estrogen levels, drugs of abuse, and alcohol levels.
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