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74 The mouth is the frst division of the alimentary tract. Important struc‑ tures of the mouth are the tongue, which contains the end organ of taste, and the teeth which divide and mix the food. The esophagus, which conveys food from the pharynx to the stomach, starts in the pharynx and finihes in the upper part of the abdominal cavity. The stomach is a dilated portion of the alimentary canal lying in the upper abdomen just under the diaphragm. It is a retaining and mixing reser‑ voir in which the process of digestion begins. The small intestine is a thin-walled muscular tube about 7 meters long. Its three portions are: duodenum, jejunum and ileum. The bile and pan‑ creatic ducts empty into the duodenum. Special structural features of the small intestine are the villi and circular folds. The intestinal glands or crypts of Lieberkühn secrete the intestinal juice containing the digestive enzymes. The large intestine is about 1.5 meters long and is divided into caecum, colon and rectum. The liver is the largest gland in the body. It is directly beneath the dia‑ phragm on the right side of the abdomen. The liver cells are arranged in architectural units, called lobules. The liver secretes bile and has many oth‑ er important functions such as stimulation of red bone marrow, production of fbrinogen, glycogenetic function and urea synthesis. The gallbladder is a pear-shaped hollow sac attached to the upper surface of the liver. It concentrates the bile. The pancreas is a long slender organ with its head to the right in the loop of the duodenum, its body posterior to the stomach and its tail touching the spleen on the left. The pancreas forms an external secretion important in digestion and an internal secretion, insulin, concerned with carbohydrate metabolism. So, dentists, who are not gastroenterologists, must know all about food and its digestion very well. 9. Read the text once again and answer the questions. 1. What does the digestive system consist of? 2. Where does the digestion start? 3. What parts of the alimentary canal does the digestion take place in? 4. What are the glands in the digestive system? 5. What are their functions? 6. What is the length of the small (large) intestine? 7. What fluids digest the food?