Meet Johnny, an average dude, who really loves FOOD (look, I rhymed)! When we approached him about this research study, he volunteered right away! Of course, it also could've been the unlimited free food that we offered...
Let's turn on the super-digesto-cam! Now, all we can see is his digestive system!
Let's focus on the mouth and esophagus first. When food enters the mouth, the teeth grind and chew the food up into much smaller pieces, this is called mechanical digestion; in the mouth, saliva also helps to break down food, this is called chemical digestion. In the esophagus, muscles squeeze food and help break it down more; the esophagus also acts as a passage from the mouth to the stomach.