The parts of the digestive system incorporate the organs of the body involved with the digestion of food. Digestion is the process the body employs to break food down into smaller particles and nutrients used for energy and growth. The parts of the digestive system include the mouth, esophagus, stomach, and small and large intestines which make up a long pathway that food travels through. The liver and pancreas also contribute vital digestive juices to the process. Food passes through the digestive system until it is completely broken down for use in other areas of the body; unusable material is excreted as waste.
When a person eats a meal, food needs to be turned into particles small enough to enter the bloodstream and travel to other areas of the body to be used for energy and growth. The digestive organs that the food travels through during this process are also known as the gastrointestinal tract or the alimentary canal. As the food moves through the system, each of the parts of the digestive system breaks it down a little further.
Digestion begins in the mouth. Solid food is chewed and mixed with saliva which contains digestive enzymes. When it is swallowed, food enters the esophagus which is a tube that carries it to the stomach. Muscle contractions called peristalsis help the food move through the esophagus in the correct direction.
Next, food enters the stomach. Food remains there until it is able to reach the intestines. While in the stomach, the food is thoroughly mixed with digestive juices and acids which break it down to a greater degree. It's also agitated using muscle contractions until it reaches a liquid state.
Two additional parts of the digestive system are the liver and the pancreas. The food does not enter these organs, but they contribute important digestive enzymes that enter the intestines through ducts to be mixed with the food. The liver makes bile, which breaks down the fat in food into tiny droplets that allow it to be absorbed. The pancreas contributes several important enzymes that help with the digestion of proteins, fats, and carbohydrates.
Liquefied food enters the small intestine, where it is mixed with additional enzymes. It slowly moves through the small intestine via peristalsis; as it moves, liquid and nutrients are absorbed through the intestinal wall into the bloodstream. Most nutrition enters the blood from the small intestine; once material reaches the large intestine, it is mainly indigestible waste and water. The water is absorbed as the material travels through the large intestine, leaving solid waste known as feces which is excreted at the end.