Small Intestine

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Digestion In Small Intestine
While digestion continues in the small intestine, it also becomes a major site for the process of absorption, that is, the passage of digested food into the bloodstream, and its transport to the rest of the body.

- The small intestine is a long, narrow tube, about 20 ft (6 m) long, running from the stomach to the large intestine. - The small intestine occupies the area of the abdomen between the diaphragm and hips, and is greatly coiled and twisted. - The small intestine is lined with muscles that move the chyme toward the large intestine. - The mucosa, which lines the entire small intestine, contains millions of glands that aid in the digestive and absorptive processes of the digestive system. The small intestine, or small bowel, is sub-divided by anatomists into three sections, the duodenum, the jejunum, and the ileum. The duodenum is about 1 ft (0.3 m) long and connects with the lower portion of the stomach. When fluid food reaches the duodenum it undergoes further enzymatic digestion and is subject. The pancreas is a large gland located below the stomach that secretes pancreatic juice into the duodenum via the pancreatic duct. There are three enzymes in pancreatic juice which digest carbohydrates, lipids, and proteins. Amylase, (the enzyme found in saliva) breaks down starch into simple sugars such as maltose. The enzyme maltase in intestinal juice completes the break down of maltose into glucose. Lipases in pancreatic juice break down fats into fatty acids and glycerol, while proteinases continue the break down of proteins into amino acids. The gall bladder, located next to the liver, secretes bile into the duodenum. While bile does not contain enzymes; it contains bile salts and other substances that help to emulsify (dissolve) fats, which are otherwise insoluble in water. Breaking the fat down into small globules allows the lipase enzymes a greater surface area for their action. Chyme passing from the duodenum next...
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