Whole saliva as mixed in the mouth contains true saliva from the major and minor salivary glands, mucosal transudations, gingival fluid, serum and blood derivatives from oral wounds, desquamated epithelial cells, expectorated bronchial and nasal secretions, bacteria, viruses, fungi and their products, other cellular components, and food debris. The specialised cells of the salivary glands take up water, salts and macromolecules from the blood to produce their individual gland secretions. Most compounds found in blood are also present in saliva, which is therefore a “mirror of the body”. Saliva is 99% water at pH 6.0 to 7.0), proteins at 0.3% (glycoproteins, phosphoproteins, enzymes and other peptides), lipids, 0.2% minerals, and other small compounds that lubricate the tongue and oral mucosa and commence the process of digestion. It has important antimicrobial properties. Saliva helps in the mastication of food by softening and the formation of food bolus. It contains enzymes, in particular amylase and salivary lipase as well as mucus and binding transport proteins such as transcobalamin-1. Saliva can be serous or mucous. The parotid gland saliva is exclusively serous, while the sublingual and intra-oral glands produce mucous saliva more important in mastication. The product of the submandibular glands is mixed. While these three major glands contribute >90% of total saliva, the minor glands, the labial, buccal, lingual, and palatal glands, supply the remainder. Adults produce 0.3 to 0.7 ml of saliva per minute, resulting in 1 to 1.5 litres daily.
The human oral microbiome may comprise up to 10,000 bacterial species but only 100 odd are common and less than half of these can be cultivated from saliva.
- ↑ Humphrey SP, Williamson RT. A review of saliva: normal composition, flow, and function. The Journal of prosthetic dentistry. 2001 Feb; 85(2):162-9.(Link to article – subscription may be required.)
- ↑ Edgar WM. Saliva and dental health. Clinical implications of saliva: report of a consensus meeting. British dental journal. 1990 Aug 11-25; 169(3-4):96-8.