The mouth is the first division of the alimentary tract whose major function is that of getting food into the system. Mechanical breakdown of non-liquid food by chewing (mastication) helps mix food with saliva which, allows for comfortable swallowing, and allows further digestion to reach a more complete state.
Saliva is produced by three paired glands, the parotid, submandibular and sublingual salivary glands. It is 99.5% water; the rest is plasma salts, and proteins (some of which are enzymatic). Following is a list of several functions which have been attributed to saliva: 1) the mucoprotein content aids in lubricating the mouth and in swallowing: 2) the water content actsas a solvent which makes taste possible; 3) its bicarbonate and phosphate buffer systems maintain a slightly acid environment in the oral cavity; 4) its lysozyme component prevents bacterial buildup in the oral cavity; 5) its amylase (ptyalin) content initiates the digestion of carbohydrates. Digestion in the mouth is inefficient at best as amylase works best in neutral or slightly alkaline conditions; plus, food is present in the mouth for only a short period of time. The irregular rough ridges or folds on the hard palate, roof of the mouth, are called rugae.