The Digestive System: An Overview

Digestion is the process by which food and liquid are broken down into smaller parts so that the body can use them to build and nourish cells, and to provide energy. The digestive tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus, consisting of :

• Mouth
• Esophagus
• Stomach
• Small intestine
• Large intestine (includes the colon and rectum)
• ANUS

Organs that help with digestion, but are not part of the digestive tract, include the following:

• Tongue
• Glands in the mouth that make saliva
• Pancreas
• Liver
• Gallbladder
• Parts of other organ systems, such as nerves and blood, also play a major role in the digestive process.

How does food move through the digestive system?

in a wave-like movement, called peristalsis, muscles propel food and liquid along the digestive tract. in general, there are 6 steps in the process of moving food and liquid through the digestive system the esophagus connects the throat above with the stomach below. it is the first organ into which the swallowed food goes.
The food then enters the stomach. This completes 3 mechanical tasks: stores, mixes, and empties:
The stomach stores the swallowed food and liquid. This needs the muscle of the upper part of the stomach to relax and accept large volumes of swallowed material. The stomach empties the contents into the small intestine.
The food is digested in the small intestine and dissolved by the juices from the pancreas, liver, and intestine. The contents of the intestine are mixed and pushed forward to allow further digestion. Last, the digested nutrients are absorbed through the intestinal walls. The waste products, including undigested parts of the food, known as fiber, and older cells that have been shed from the mucosa, move into the colon. Waste products in the colon usually remain for a day or two until the feces are expelled by a bowel movement.