A trip through the tract
1979
Digestion begins in the mouth as food is chewed and mixed with saliva which starts the process of breaking down carbohydrates. In the stomach, food is churned into a liquid mass called chyme, and two enzymes, rennin and pepsin, start breaking down proteins. Meals rich in proteins and fats stay in the stomach longest, and leave the feeling of being "stuffed". From the stomach food passes to the small intestine where pancreatic enzymes complete the breakdown of protein and carbohydrate and begin that of fat. Bile salts from the gallbladder aid in fat digestion. Amino acids, sugar units and small fatty acids are absorbed through the intestinal wall, entering the blood system. Vitamins and minerals attach to binding sites on the intestinal wall and are then absorbed. Most nutrients have been absorbed before food passes to the large intestine which forms feces of undigested fiber, bacteria, water and bile pigments. Tips to keep the digestive tract operating smoothly during the holiday season are included.
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