The regulated release of saliva from the salivary glands. In man, the saliva is a turbid and slightly viscous fluid, generally of an alkaline reaction, and is secreted by the parotid, submaxillary, and sublingual glands. In the mouth the saliva is mixed with the secretion from the buccal glands. In man and many animals, saliva is an important digestive fluid on account of the presence of the peculiar enzyme, ptyalin.