Answer
Absorption of most molecules and nutrients is done in the small intestine, not the stomach, because the wall of the small intestine absorbs the sugar, amino acid, glycerol, and fatty acid molecules that were the products of the digestive process. The mucosa of the small intestine is modified for absorption. It has been suggested that the surface area of the small intestine is approximately that of a tennis court. This great surface area absorbs more nutrients than a smaller area would. The mucosa of the small intestine contains fingerlike projections called villi, which give the intestinal wall a soft, velvety appearance. A villus has an outer layer of columnar epithelial cells, and each of these cells has thousands of microscopic extensions called microvilli. The microvilli contain enzymes, called brush border enzymes, that complete the digestive process. The microvilli greatly increase the surface area of the villus for the absorption of nutrients. Nutrients are absorbed into the vessels of a villus . A villus contains blood capillaries and a small lymphatic capillary called a lacteal. As you know, the lymphatic system is an adjunct to the cardiovascular system. Lymphatic vessels carry a fluid called lymph to the cardiovascular veins. Sugars (monosaccharides) and amino acids enter the blood capillaries of a villus. Single molecules of glycerol, called monoglycerides, and fatty acids enter the epithelial cells of the villi. Lipoprotein droplets, called chylomicrons, are formed when monoglycerides and fatty acids are rejoined in the villi epithelia cells. Chylomicrons then enter a lacteal. After nutrients are absorbed, they are eventually carried to all the cells of the body by the bloodstream.
Work Step by Step
Absorption of most molecules and nutrients is done in the small intestine ,not the stomach, because the wall of the small intestine absorbs the sugar, amino acid, glycerol, and fatty acid molecules that were the products of the digestive process. The mucosa of the small intestine is modified for absorption. It has been suggested that the surface area of the small intestine is approximately that of a tennis court. This great surface area absorbs more nutrients than a smaller area would. The mucosa of the small intestine contains fingerlike projections called villi, which give the intestinal wall a soft, velvety appearance. A villus has an outer layer of columnar epithelial cells, and each of these cells has thousands of microscopic extensions called microvilli. The microvilli contain enzymes, called brush border enzymes, that complete the digestive process. The microvilli greatly increase the surface area of the villus for the absorption of nutrients. Nutrients are absorbed into the vessels of a villus . A villus contains blood capillaries and a small lymphatic capillary called a lacteal. As you know, the lymphatic system is an adjunct to the cardiovascular system. Lymphatic vessels carry a fluid called lymph to the cardiovascular veins. Sugars (monosaccharides) and amino acids enter the blood capillaries of a villus. Single molecules of glycerol, called monoglycerides, and fatty acids enter the epithelial cells of the villi. Lipoprotein droplets, called chylomicrons, are formed when monoglycerides and fatty acids are rejoined in the villi epithelia cells. Chylomicrons then enter a lacteal. After nutrients are absorbed, they are eventually carried to all the cells of the body by the bloodstream.
