Significance of human salivary and mucosa mucins in the area of the upper respiratory and digestive tract

The importance of the mucins in saliva and mucus for the mucous membranes of the aero-digestive tract is underlined. The biochemistry of the mucins is briefly talked over, with the biological significance of the neuraminic acid being especially evoked. Decisive functions of the mucins for the mucous membranes of the upper respiratory and alimentary tracts, such as the protective, lubrication and transport functions, as well as their contribution to the formation of surface tension are discussed. Some of the few known pathobiochemical relationships are described. Pathobiochemistry of the mucins may also contribute to a better understanding of unsettled oncological problems of the aero-digestive tract. Mucin changes due to noxae--as e.g. by alcohol--may lead to a reduction of the mucous and salivary protective functions. After restricted mucin protective function, noxae--such as tobacco smoke--may then exercise their cancerogenic effects on the then unprotected epithelium.