The stomach is responsible for breaking down protein from food and drink. Dr. Malone, can you tell us more about the stomach?
Absolutely, Major Spencer. The stomach, located in the upper abdomen, receives food from the esophagus through a ringlike bundle of muscles called the lower esophageal sphincter, or LES. As the food enters the stomach, it mixes with digestive juice produced by the stomach, called stomach acid.
Ridges of muscle that line the stomach, called rugae, contract periodically to churn food and drink, helping to mix them with the stomach acid.
While the stomach is capable of accepting large volumes of swallowed food from the esophagus, it empties its contents, called chyme, more slowly. Chyme passes through another ringlike bundle of muscles, called the pyloric sphincter, from the stomach into the small intestine.