Category C - full version without watermark 1024x576 (check terms and conditions at www.teledesign.de) The embed version with watermark is free of charge. - description: Food taken into the mouth is first broken down into smaller pieces by the teeth. The bolus, which is now a battered, moistened, and partially digested ball of food, is swallowed, moving to the pharynx (throat) at the back of the mouth. In the pharynx, rings of muscles force the food into the esophagus, the first part of the upper digestive tube. The esophagus extends from the bottom part of the throat to the upper part of the stomach. Chemical digestion begins in the stomach. Food in the stomach is broken down by the action of gastric juice, and passed through the pyloric sphincter, the opening between the stomach and the small intestine, the duodenum,. Pancreas secretes pancreatic juice into the duodenum through the pancreatic duct and the gall bladder, empties bile into the duodenum to break down carbohydrates, fats, and proteins. The inner lining of the small intestine is composed of up to five million tiny, fingerlike projections called villi. The villi increase the rate of absorption of nutrients into the bloodstream by greatly increasing the surface area of the small intestine. The ileum, the last section of the small intestine, is the longest, measuring 11 feet (3.4 meters). Certain vitamins and other nutrients are absorbed here.