Category A - full version without watermark 720x576 (check terms and conditions at The embed version with watermark is free of charge. - Description: At a first glance the tongue seems nothing more than a helpful tool for food intake. The back of the tongue is divided into two halves and coated with a relatively rough and thick mucosa. At a closer look, one discovers blood vessels, neurons and numerous small glands, providing constant rinsing with saliva. Saliva contains enzymes for digestion and immune defense. On the mucosa there are so called papillae. Some of them are responsible for mechanical tasks, some see to taste. All papillae are surrounded by a moat. There, little "rinsing" glands and also the taste buds are situated. Normally the tongue cleans itself by chewing solid food and constant rinsing from the little glands. If this natural process is disturbed by disease or poor diet, a white film forms from debris, mucus and micro-organisms.