“Salivary amylase” is a digestive enzyme secreted by the salivary glands. It is responsible for starting the breakdown of the insoluble polysaccharide “starch” into soluble dextrins (oligosaccharides), maltose (disaccharide) and glucose (monosaccharide) in the mouth so that starch can be absorbed (amylon is a Greek word that means “starch”). Amylase is found in saliva and breaks starch into maltose and dextrin. This form of amylase is also called "ptyalin". Salivary amylase is inactivated in the stomach by gastric acid. In gastric juice adjusted to pH 3.3, ptyalin was totally inactivated in 20 minutes at 37°C. In contrast, 50% of amylase activity remained after 150 minutes of exposure to gastric juice at pH 4.3. Both starch, the substrate for ptyalin, and the product (short chains of glucose) are able to partially protect it against inactivation by gastric acid.