Digestion begins as soon as the burger enters the mouth. Saliva breaks down starch from the burger’s bun into glucose. By chewing, the each bite of the burger is further reduced into smaller pieces. In addition, the saliva helps in making the burger mushy that enable us to easily swallow it and neutralizes acids that are present in the burger. By swallowing, the chewed burger is then pushed down the esophagus which then directs it to the stomach.
Gastric juices in the stomach contain hydrochloric acids which kills microorganisms that may be present from the food and lowers the pH level of the stomach activating pepsin. Pepsin breaks down the protein from the meat patty into peptides. However, pepsin only digests protein minimally. On the other hand, the enzyme lipase also found in the stomach but are secreted by the pancreas are responsible for breaking down lipids from the meat patty and mayonnaise into smaller molecules that could be absorbed by the body.
The food is digested in the stomach until it dissolves into a semi-fluid paste called chime which is then released into the duodenum. The duodenum is the first part of the small intestine where the major digestion takes place. Lipid that has partially been digested in the stomach is further broken down into smaller molecules in the duodenum through the aid of the bile which were secreted from the liver.
Streapsin, which is secreted by the pancreas, also helps in the digestion of lipids into fatty acids and glycerol. Protein that has not been digested in the stomach is also digested in the duodenum through the enzymes trypsin and chymotrypsin, both secreted by the pancreas. Trypsin is also responsible for breaking down hydrolyse peptides into smaller amino acids. With the digestion complete, the nutrients are now able to be absorbed by the body through the millions of villi found in the small intestine.