The gastrointenstinal tract begins at the mouth and ends at the rectum. It is where the digestion of food takes place. During digestion, the body breaks down the food we eat and processes all of its important energy and substances. These substances are then transmitted into other parts of the body via the circulatory system.

The digestion of food begins at the mouth. There, the teeth cut up the food into manageable, swallowable pieces. At the same time, the mouth secretes spit, which helps to break down the food. After being swallowed, the food then travels into the stomach through the esophagus. In the stomach, the food is broken down into liquid.

From the stomach, the processed food continues its journey into the small intestine. There, the food is processed with the help of substances secreted by the liver and the pancreas. In the small intestine, the food is broken down into even smaller particles. The substances and energy contained it are absorbed by the blood vessels of the small intestine. 

After travelling through the small intestine, the food reaches the large intestine. There, the water from food is absorbed into the bloodstream. After this, all the material that has not yet been processed is removed from the digestive system through the rectum and the anus.