The process of digesting a cheeseburger is quite amazing. It begins in the mouth where mastication takes place. Mastication refers to the physical breaking down the food into the smaller pieces by the chewing and grinding of the teeth. The process of mastication triggers the salivary glands to release saliva which has the digestive enzyme, amylase that breaks down the starch present in the cheeseburger to simple sugars. The saliva also contains water and mucus that lubricate the food and as chewing goes on, the tongue rolls it into boluses and pushes to the pharynx for swallowing. The food moves through the esophagus by the process of peristalsis and enters the stomach.

The arrival of the burger in the stomach triggers the gastric glands to release gastric juice that has hydrochloric acid of pH 2.0 that neutralizes the salivary alkaline pH and makes the conditions necessary for the action of pepsin. The hydrochloric acid also activates the pepsinogen to the active enzyme to pepsin that breaks down the proteins in the cheeseburger: the bacon, cheese and the beef, into peptide chains. The hydrochloric acid also kills any harmful bacteria and other organisms that might be present in the food. The food leaving the stomach is now known as chyle and makes its way to the small intestines.

Most of the digestion of the cheeseburger takes place in the small intestines. Absorption also takes place at this part of the digestion system. The intestinal walls produce the intestinal fluid that has digestive enzymes that break down starch, lipids, polypeptides, sucrose, maltose and lactose. The peptide bonds in proteins are broken down by peptidases; disacchridases break down the disaccharides into simple sugars and the lipases break down fats into glycerol and fatty acids. The small intestines also have absorptive cells that absorb the fats present in the burger. There also goblet cells that produces a protective lining that prevents the intestinal walls from being damaged by the digestive enzymes. The intestines also produce hormones that stimulate the pancreas and the liver to produce secretions that will act on the burger. The live produces bile that neutralizes the stomach acid in the small intestines and emulsifies the fats from the cheeseburger. This emulsification assists in fat digestion. The secretions from the pancreases stop the action of pepsin while providing the right performance environment for the pancreatic enzymes.

The Cheeseburger leaving the small intetssines is now called Chyme and makes its way to the large intestines which has a mucosal lining with much mucus producing gland that convert the chyme into feces. These feces are stored until the process of defecation takes place. The feces then move to the rectum which is a smooth muscle that is relatively thick as compared to the rest of the digestive tract. Through the process of peristalsis, the rectum moves the feces to the anus, a canal that releases the feces though the external sphincter, to the outside.