'How proteins in the diet are disassembled and then reassembled to form useful proteins in the body’ The human gastrointestinal tract has the complex task of breaking down dietary macromolecules such as proteins, carbohydrates and lipids. In their food form, these macromolecules are unable to be absorbed by the epithelial cells in the digestive tract so need to be deconstructed into their component parts. The production of protein is one of the bodies key metabolic processes. The journey from mouth to anus through the digestive track involves numerous muscles and secretions whilst incorporating several glands and organs along the way. This essay will firstly discuss proteins and their importance in the diet. It will then go on to discuss…show more content… The intestines have evolved to have as much surface area as possible to aid in the optimum digestion of nutrients into the blood. As chyme passes through the pyloric sphincter it is mixed with enzymes, trypsin, chymotrypsin and carboxypeptidase, from the pancreas. These enzymes denature proteins into peptides of different lengths. The small intestines surface area is covered in villi which in turn have their own villi called microvilli, known as the brush border (Fig 1.2). Aminopeptidase, located within the epithelial cells of the brush border is released. Aminopeptidase releases amino acids from one end of the peptide chain whilst chymotrypsin releases amino acids from the other end. Free Amino acids are the end result of digestion. Amino acids are absorbed into the walls of the small intestines and are transported into the lymphatic system or into the blood stream. The Open University, (Sk277 Cells and Nutrition, 2006), states that 98% of proteins are digested whilst only 2% are excreted. Once through the small intestines the chyme moves onto the large intestines where the water vitamins and minerals are
