After swallowing his delicious hamburger, it now travels through David's esophagus. The mucous glands on the inside help keep the tube moist so his food travels easier.

Next, his hamburger has made it to his stomach. David's stomach acts as a storage tank for all of his food, then passes it on through the rest of the digestive system, including the small and large intestine.

David's digestive system is almost always at work. It takes 24 to 72 hours in order for his food to completely digest. But only after about six to eight hours his food has passed through both his stomach and small intestine.