The gastrointestinal tract is one of the most important anatomical body systems, both humans and animals. Its main role is the passage, digestion, utilization and excretion of food.
 In humans actually starts from the mouth and ends at the anus.  It includes the following sections:

Oral cavity
* Pharynx
* Esophagus *
Duodenum (sometimes included in the small intestine)
Small and large intestines

In the gastrointestinal system installed and the following organs (mainly because they are in the abdomen):

* Complicated appendicitis
Biliary system
*  Spleen

The term gastrointestinal tract digestive tube meant the stomach, the thin and large intestines (sometimes the esophagus).