The mouth is the entrance to the human digestive system. Teeth gnash the food, breaking it down mechanically, while the three salivary glands release saliva containing the enzyme amylase, which breaks down starch and fat chemically. Saliva makes food easier to swallow by moistening it. After entering the body at the back of the throat, food travels down the esophagus, being transported not by gravity but by muscular contractions. Read more on the following site..
Where is the Digestive System Located? – http://answers.ask.com/Health/Diseases/where_is_the_digestive_system_located