The gastrointestinal or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and expels the remaining waste.
The GI tract differs substantially from animal to animal. For instance, some animals have multi-chambered stomachs.
The process of digestion
Food, after being partially broken down in the mouth, passes through the esophagus to the stomach, where the process of breakdown continues. It then passes to the small intestine where further breakdown occurs, and the useful particles are absorbed into the bloodstream. The remaining particles pass through the large intestine and are ultimately expelled.
The digestive system is a series of hollow organs joined in a long, twisting tube. Inside this tube is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food.
Why digestion is important
When we eat such things as bread, meat, and vegetables, they are not in a form that the body can use as nourishment. Our 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 that the body can use them to build and nourish cells and to provide energy.
Intestine Facts for Kids. Kiddle Encyclopedia.