What Is the Definition of Digestion?

Digestion is defined as the mixing of food after it has been chewed and swallowed with digestive juices. The food moves along the digestive tract and is broken down into larger molecules of food, which in turn are then broken down further as it keeps moving along. The digestive process beings in the mouth and is finished in an organ known as the small intestine.

Significance

• Digestion is one of the most significant jobs that your body must carry out to remain healthy. When you eat food or drink liquids, what you are ingesting is not yet in a form that your body can use for energy. The food and drink needs to be processed as it were into much smaller forms before the nutrients can be absorbed into your bloodstream and dispersed to cells all over your body. Digestion accomplishes this important task.

Features

• The human digestive system is composed of one hollow organ after another that is virtually connected as a long and twisting tube that runs from the mouth to the anus. This is known as the digestive tract and is made up of the mouth, esophagus, stomach, small and large intestines, rectum and the anus. Each of these performs a specific job. The digestive tract is lined with mucosa, which aids in the digestive work. Smooth muscles line the digestive tract that helps break food up and move it along to the next junction. The liver and pancreas are two organs that produce digestive juices and send them to the tract, while the gallbladder stores these juices until they are needed.

Function

• Once food is chewed up or swallowed the digestion begins. Food that has been swallowed enters the esophagus, which is a long, hollow, muscular tube that connects to the stomach below it. A structure known as the lower esophageal sphincter sits at the boundary between the esophagus and stomach. It acts as a sort of valve, relaxing as food approaches to allow it access to the stomach and then closing again. Once in the stomach the digestion starts in earnest. The stomach stores the food and liquids, mixes it with digestive juices that it produces, and then empties this mixture into the small intestine. There the food and liquids are broken down and the nutrients begin to be absorbed through the intestinal wall and transported to the other parts of the body. The remaining product goes into the large intestine, or colon. It is whatever could not be digested and it remains there until it is expelled from the body through the rectum by means of a bowel movement.

Time Frame

• The time it takes to digest a meal depends on the person. For a normal healthy adult it takes between 24 and 72 hours. Once you have eaten it takes 6 to 8 hours for the food to pass through your stomach and into the small intestine. The elimination of undigested food starts after 24 hours and the complete elimination of the entire meal can take several days. In the stomach, carbohydrates spend the least amount of time because they can be broken down more quickly than proteins and fats, which remain there the longest.

Considerations

• Digestive glands play an important role in the digestion process. The first ones that go to work are located in the mouth and are called the salivary glands. They produce saliva that has enzymes that right away go to work on starches. These enzymes speed up the chemical reactions that occur during digestion. The stomach lining contains digestive glands that produce acid and an enzyme with protein. The thick layer of mucus that coats the stomach keeps these acidic juices from actually going through the stomach lining. Once out of the stomach the food meets up with enzymes courtesy of the pancreas and liver. The liver makes bile, which is effective on fat. The combined effects of all these chemical reactions digest the food and liquids.