The stomach is on the upper-left area of the abdomen below the liver and next to the spleen. It stores and breaks down the foods and liquids we eat before they move to digestion.

When the stomach is empty, the inside has small folds called rugae. Rugae allow the stomach to expand to accommodate large meals. They also grip the food inside the stomach to help physically break it down.

The average stomach can hold about 1.5 gallons of food and liquid at maximum capacity. It only holds food for three to five hours, before passing it along the digestive tract.

The stomach’s main tool for digestion is the powerful mix of secretions collectively called gastric juices. To counteract these strong juices, the stomach protects itself with mucus-like secretions. Without this protection, the stomach would essentially digest itself (“auto-digestion”), which is a common cause of stomach ulcers.

Cells lining the stomach create the following active ingredients in gastric juices:

  • Pepsin: This protein-digesting enzyme activates when food enters the stomach.
  • Hydrochloric acid: This extremely strong acid breaks down food and any other foreign materials such as bacterial pathogens. Two muscular rings called sphincters also provide additional defense against the chemicals in the stomach by moving contents along. The esophageal sphincter separates the esophagus and the stomach. When that muscle doesn’t relax properly, it feels like it is difficult to swallow. On the opposite end of the stomach, the pyloric sphincter regulates the speed at which food moves down to the small intestine.

After the stomach has done its work, the highly acidic mixture of gastric juices and food (known as chyme) leaves the stomach, moves past the pyloric sphincter, and goes into the duodenum before entering the small intestine.

Because the chemicals in the stomach work due to a subtle balance, many problems can arise with the stomach. Some common conditions related to the stomach include:

  • Indigestion
  • Heartburn
  • Nausea
  • Vomiting
  • Diarrhea
  • Peptic Ulcers
  • Crohn’s disease