The Human Body: Digestive System
The digestive system is one of the most complex systems of the body. The digestive system is made up of organs that break down food into vitamins, minerals, protein, carbohydrates, and fats, which the body needs for energy, growth, and repair.
The main organs of the digestive system are mouth, esophagus, stomach, small and large intestines, anus, appendix. Accessory organs to the alimentary canal include the liver, gallbladder, and pancreas.
When you eat foods-such as bread, meat, and vegetables-they are not in a form that the body can use as nourishment. Food and drink must be changed into smaller molecules of nutrients before they can be absorbed into the blood and carried to cells throughout the body. Digestion is the process by which food and drink are broken down into their smallest parts so the body can use them to build and nourish cells and to provide energy.
Digestion involves mixing food with digestive juices, moving it through the digestive tract, and breaking down large molecules of food into smaller molecules. Digestion begins in the mouth, when you chew and swallow, and is completed in the small intestine.
In human body, food enters the mouth, being chewed by teeth, and broken down by the saliva from the salivary glands. Then it travels down the esophagus into the stomach, where acid begins physical break down of some food, and chemical alteration of some. The "leftovers" go through the small intestine, through the large intestine, and are excreted during defecation.