Step 1.
When you chew, saliva is added. In addition to being a liquid which moistens, softens and lubricate food, saliva contains enzyme called amylase, which breaks down starch. In the mouth the Meat patty and the bread could be broken down and digested. Step 2.
The oesophagus has two layers. Its interior is lined with cells that are packed very closely together creating a smooth surface. The circular muscle around the outside of the oesophagus is also smooth. Your swallow forces the food toward the stomach.
Step 3.
Once it reaches your stomach the cheeseburger is broken down even more, the amylase that went to work on the food in your mouth is taken down by acid. Hydrochloric acid is the main component