Describe anatomical features of the small intestine that facilitate absorption. Include a discussion of the absorption of water-soluble versus fat-soluble nutrients

Answer 1

?The inner surface of the small intestine is wrinkled into hundreds of folds. Each fold is contoured into thousands of fingerlike projections called villi. A single villus is covered with microscopic hairs called microvilli. In the crevices between the villi lie the crypts-tubular glands that secrete the intestinal juices into the small intestine. Nearby goblet cells secrete mucus. Within its 10-foot length, which provides a surface area equivalent to a tennis court, the small intestine traps and absorbs the nutrient molecules. To remove the absorbed molecules rapidly and provide room for more to be absorbed, a rush of circulating blood continuously washes the underside of this surface, carrying the absorbed nutrients away to the liver and other parts of the body. When a nutrient molecule has crossed the cell of a villus, it enters the bloodstream or the lymphatic system. The water-soluble nutrients and the small products of digestion are released directly into the bloodstream and guided directly to the liver. The larger fats and the fat-soluble vitamins are assembled into chylomicrons, which are released into the lymphatic system. They move through the lymph until they can enter the bloodstream at a point near the heart. Consequently, chylomicrons bypass the liver.