The Stomach (Human Anatomy): Picture, Function, Definition, Conditions, and More

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Human Anatomy

Picture of the Stomach

The stomach is a muscular organ located on the left side of the upper abdomen. The stomach receives food from the esophagus. As food reaches the end of the esophagus, it enters the stomach through a muscular valve called the lower esophageal sphincter.

The stomach secretes acid and enzymes that digest food. Ridges of muscle tissue called rugae line the stomach. The stomach muscles contract periodically, churning food to enhance digestion. The pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.

Stomach Conditions

Gastroesophageal reflux: Stomach contents, including acid, can travel backward up the esophagus. There may be no symptoms, or reflux may cause heartburn or coughing.
Gastroesophageal reflux disease (GERD): When symptoms of reflux become bothersome or occur frequently, they’re called GERD. Infrequently, GERD can cause serious problems of the esophagus.
Dyspepsia: Another name for stomach upset or indigestion. Dyspepsia may be caused by almost any benign or serious condition that affects the stomach.
Gastric ulcer (stomach ulcer): An erosion in the lining of the stomach, often causing pain and/or bleeding. Gastric ulcers are most often caused by NSAIDs or H. pylori infection.
Peptic ulcer disease: Doctors consider ulcers in either the stomach or the duodenum (the first part of the small intestine) peptic ulcer disease.
Gastritis: Inflammation of the stomach, often causing nausea and/or pain. Gastritis can be caused by alcohol, certain medications, H. pylori infection, or other factors.
Stomach cancer: Gastric cancer is an uncommon form of cancer in the U.S. Adenocarcinoma and lymphoma make up most of the cases of stomach cancer.
Zollinger-Ellison syndrome (ZES): One or more tumors that secrete hormones that lead to increased acid production. Severe GERD and peptic ulcer disease result from this rare disorder.
Gastric varices: In people with severe liver disease, veins in the stomach may swell and bulge under increased pressure. Called varices, these veins are at high risk for bleeding, although less so than esophageal varices are.
Stomach bleeding: Gastritis, ulcers, or gastric cancers may bleed. Seeing blood or black material in vomit or stool is usually a medical emergency.
Gastroparesis (delayed gastric emptying): Nerve damage from diabetes or other conditions may impair the stomach’s muscle contractions. Nausea and vomiting are the usual symptoms.