Human Digestion Essay

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Human Digestion The digestive process begins as soon as food enters the mouth. Saliva begins to immediately break down sugars and starches, while the teeth grind down the food. Food then enters the esophagus and is swallowed, where it then enters the stomach for further breakdown by way of stomach acids. Very little of the food is actually digested in the stomach. Instead, the acids work to break down the food for easier digestion in the intestines. As the food is broken down to a thick paste-like substance known as chyme, it moves past the pyloric sphincter and into the small intestine. The first section of the small intestine, the duodenum, secretes digestive enzymes like amylase, maltase, sucrase, lactase, lipase and pepsin, to break down the chyme into even smaller parts that the body can then convert into usable energy. Some other organs that secrete chemicals to aid in the digestion process include the pancreas, liver, and gall bladder. The pancreas secretes trypsin and chymotripsin. The liver and gall bladder secrete bile, used for the emulsification of fats. The second section of the small intestine, the jejunum, is where the majority of food is absorbed into the bloodstream. The last section of the small intestine, the ileum, is where the remainder of nutrients is absorbed. What is not absorbed by the small intestine passes into the large intestine, which includes the colon and rectum. Here, peristalsis (the contractions of the muscles around the stomach and intestines that assist in moving food through the system) slows, allowing the growth of bacteria, which aids in the digestion of fiber and the absorption of some vitamins. The colon absorbs water, vitamins and minerals not absorbed by the small intestine. Anything that has not been absorbed by this point is then eliminated through the rectum and anus, thus completing the journey food takes through the

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