Digestive System Function Of The Human Digestive System

by Trisha on August 23, 2009

The digestive system is a group of organs joined in a long, twisting tube from the mouth to the anus. It is also called the alimentary canal and the gastrointestinal tract.

Digestive System Diagram | Mouth, Stomach, Small Intestine | How It Works

The major parts of that tube are:
Mouth – Esophagus – Stomach – Small intestine – Duodenum
Jejunum – Ileum – Large intestine (also called the colon) – Cecum
Ascending colon – Transverse colon – Descending colon
Sigmoid colon – Rectum

The large, hollow organs of the digestive system contain muscle that enables their walls to move. The movement of organ walls can propel food and liquid and also can mix the contents within each organ. Typical movement of the esophagus, stomach and intestine is called peristalsis.

Digestive-system-diagram-page

Digestive System Function : Inside this tube is a lining called the mucosa which contains tiny glands that produce juices to help digest our food.
Other organs that aren’t part of the tube – the liver, gallbladder and the pancreas – produce and store digestive juices that are used in the intestine. In addition, parts of other organ systems (for instance, nerves and blood) play a role in the intestinal tract.

After we swallow, food enters the esophagus. At the end of the esophagus, a ring-like valve opens, to let food enter the stomach.

The stomach stores the food and liquid, mixes it with digestive juices, and then empties its contents slowly into the small intestine. Food is further digested in the small intestine, where nutrients from the food are absorbed through the intestinal walls. Digestion continues in the large intestine or colon. The waste products of this process then remain in the colon, usually for a day or two, until the feces are expelled by a bowel movement.

Carbohydrates: Digestible carbohydrates

Protein: Foods such as meat, eggs, and beans consist of giant molecules of protein that must be digested by enzymes before they can be used to build and repair body tissues. An enzyme in the juice of the stomach starts the digestion of swallowed protein. Then in the small intestine, several enzymes from the pancreatic juice and the lining of the intestine complete the breakdown of huge protein molecules into small molecules called amino acids. These small molecules can be absorbed through the small intestine into the blood and then be carried to all parts of the body to build the walls and other parts of cells.

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Fats: Fat molecules are a rich source of energy for the body. The first step in digestion
of a fat such as butter is to dissolve it into the watery content of the intestine. The bile acids produced by the liver dissolve fat into tiny droplets and allow pancreatic and intestinal enzymes to break the large fat molecules into smaller ones. Some of these small molecules are fatty acids and cholesterol. The bile acids combine with the fatty acids and cholesterol and help these molecules move into the cells of the mucosa. In these cells the small molecules are formed back into large ones, most of which pass into vessels called lymphatics near the intestine. These small vessels carry the reformed fat to the veins of the chest, and the blood carries the fat to storage depots in different parts of the body.

Vitamins: Another vital part of food that is absorbed through the small intestine are vitamins. The two types of vitamins are classified by the fluid in which they can be dissolved: water-soluble vitamins (all the B vitamins and vitamin C) and fat-soluble vitamins (vitamins A, D, E, and K). Fat-soluble vitamins are stored in the liver and fatty tissue of the body, whereas water-soluble vitamins are not easily stored and excess amounts are flushed out in the urine.

Water and salt. Most of the material absorbed through the small intestine is water in which salt is dissolved. The salt and water come from the food and liquid you swallow and the juices secreted by the many digestive glands.

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