What You Should Know About Your Stomach
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Medically reviewed by Robert Burakoff, MD
The stomach is a muscular, J-shaped organ located in the upper left abdominal area. As part of the digestive system, the stomach temporarily stores food and helps break down food using contractions and stomach acid. The stomach also produces a protein that helps your intestines absorb vitamin B12.
As a main digestive organ, the stomach's breakdown of food helps your body absorb essential nutrients and eliminate waste. Several health issues can originate in the stomach, including acid reflux, indigestion, stomach ulcers, and stomach cancer. If left untreated, stomach issues can cause pain, disrupt digestion, and prevent nutrient absorption.
Anatomy of the Stomach
The stomach looks like an inflated, J-shaped sack that's hollow inside. Here's what to know about how the organ is structured, where it's located, and whether there can be any variations in its anatomy.
Structure
There are four main regions that make up your stomach. These regions are the:
Cardia: This is the top-right opening where food passes into the stomach. This area also secretes mucus that protects and coats the inner stomach wall.
Fundus: This dome-shaped area makes up the top-left region of the stomach, which is mainly responsible for releasing stomach acid (gastric acid).
Body: This is the main, central portion of the stomach.
Pylorus: The funnel-shaped opening at the bottom-right portion of the stomach moves partially digested food out of the stomach.
The stomach is also made up of layers of tissue, muscle, and mucus. These layers include the:
Serosa: Smooth tissue that forms a protective lining outside the stomach
Muscularis: Three layers of smooth muscle (outer longitudinal, middle circular, and inner oblique muscles)
Submucosa: A thick layer of dense connective tissue containing blood vessels, lymphatic cells, and nerves
Mucosa: The innermost stomach layer made of thin tissue (called epithelium) and glands that secrete protective mucus, hormones, and stomach acid
Location
The stomach sits in the left side of your upper abdomen—right under your liver—and is part of your digestive system. Your digestive system includes organs in the gastrointestinal (GI) tract like the mouth, esophagus, stomach, small intestine, and large intestine.
The top opening of the stomach (the cardia) connects to your esophagus—a tube that carries food from the throat to the stomach. There is also a sphincter, or a ring-shaped muscle, at the end of your esophagus that contracts to move food into the stomach. The bottom funnel section of the stomach (the pylorus) connects to your small intestine via the pyloric sphincter. This muscle acts like a valve and contracts to move stomach contents into the first section of your small intestine (the duodenum).
Anatomical Variations
Genetic abnormalities of the stomach are not well understood. Some abnormal vertical positions of the stomach can include the curve of the stomach facing forward, backward, or to the right.
Irregular childhood development or regularly sucking in the stomach—to appear thinner or reduce pain—can also cause an hourglass-shaped stomach. This is when the stomach narrows in the center and appears divided into two sections.
What Does the Stomach Do?
The stomach helps digest food. The stomach's muscle contractions and acid production break down food into smaller parts. As food enters the stomach via the esophagus, the upper areas of the stomach (the cardia, fundus, and body) relax to let the stomach fill with food. The lower stomach muscles contract to help break down and mix food, a process known as mechanical digestion.
Meanwhile, the stomach's gastric glands release a hormone called gastrin to start chemical digestion. Gastrin helps tell your stomach to release food-digesting gastric acid (stomach acid) made of hydrochloric acid and pepsin, an enzyme that digests proteins in food.
Together, stomach acid and muscle contractions start digesting food in 20-second waves. At the same time, the pyloric sphincter at the bottom of the stomach opens to move partially digested food and stomach acids—a mixture called chyme—into the small intestine. It takes about two to four hours for the stomach to move all its contents to the small intestine, where the body starts absorbing nutrients.
Stomach lining cells also produce intrinsic factor, a protein that helps your intestines absorb vitamin B12. While in the stomach, intrinsic factor attaches to B12 before it travels into your small intestines. Once in your small intestine, B12 absorbs into your bloodstream and helps your body form and grow red blood cells. Additionally, the stomach absorbs water when dehydrated, some medications, and some water-soluble vitamins.
Associated Conditions
There are several health problems that originate in the stomach. Health conditions and injuries associated with the stomach include:
Dyspepsia
Also called indigestion or upset stomach, dyspepsia is common and can happen after binge drinking; eating acidic, spicy, or fatty foods; eating too quickly; experiencing stress; smoking; or taking certain medications. Symptoms include stomach discomfort and pain, bloating, gas, and feeling uncomfortably full after a meal.
Gastroesophageal Reflux (GER) and Gastroesophageal Reflux Disease (GERD)
Also called acid reflux or heartburn, GER occurs when stomach acid escapes up your food pipe. People with GER often experience burning pain in the mid-chest, as well as indigestion or regurgitation. GER can happen occasionally and, when it does, usually happens after meals or at night.
GERD is a chronic digestive condition where people experience GER symptoms daily or several times a week. If left unmanaged, people with GERD can have permanent damage to their esophagus.
Stomach Ulcers
Also called gastric or peptic ulcers, these open sores develop on the stomach lining and cause pain and other indigestion symptoms. Helicobacter pylori (H. pylori ) infections or stomach lining damage from nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin and ibuprofen are the leading causes.
Gastritis, Gastroenteritis, and Gastropathy
These three conditions cause inflammation or damage to the lining of your stomach.
Gastritis is inflammation of the innermost stomach lining and can cause stomach pain, vomiting, weight loss, and nausea. Gastritis is usually caused by autoimmune disorders or H. pylori bacterial infections—which is more common in adults older than 60.
Gastroenteritis causes stomach and intestinal lining inflammation. Symptoms include stomach cramps, diarrhea, nausea, fever, and vomiting. Stomach viruses or food poisoning often cause gastroenteritis.
Gastropathy is stomach lining damage, with little or no inflammation. NSAIDs, alcohol, and bile can cause gastropathy. Gastropathy can eventually erode away the stomach lining and cause stomach ulcers.
Gastroparesis
Also called delayed gastric emptying, gastroparesis slows down or stops partially digested food as it moves from the stomach to small intestine. Gastroparesis is caused by stomach muscles that don't work correctly. Symptoms of gastroparesis include abdominal pain, heartburn, and nausea. If left untreated, the condition can lead to malnutrition.
Stomach Cancer
This type of cancer targets the cells that line the stomach. Stomach cancer can also form in the mucus layer, where the esophagus meets the stomach, nerve cells, and lymphatic cells. Early signs of stomach cancer can include indigestion, nausea, bloating, and heartburn. More advanced symptoms include yellowing of the eyes and skin (jaundice), fluid build-up in the abdomen (ascites), stomach pain, blood in stool, and trouble swallowing.
Chronic gastritis, GERD, smoking, and a family history of the condition put you at risk of developing stomach cancer.
Gastric Perforation
This injury refers to a hole through the stomach wall that requires surgical repair. Besides a puncturing wound, gastric perforation can be caused by stomach ulcers or tumors. Two of the most common initial signs of a perforation are sudden swelling of and pain in the stomach.
Diagnostic Testing
If you experience persistent stomach issue symptoms, talk with your healthcare provider. They may refer you to a digestive system specialist called a gastroenterologist. Standard tests healthcare providers perform on the stomach to diagnose health issues include:
Upper GI series: During the test, you'll drink a chalky liquid containing barium that will appear on an X-ray. A healthcare provider then uses an X-ray to track the barium and see how your GI tract works. This test can help diagnose stomach ulcers and GERD.
Gastric emptying test: Also called a gastric emptying study, this test measures the time it takes for food to exit your stomach. You'll eat food containing a small amount of radioactive material, known as a tracer, that is tracked on a scanning device. This test helps diagnose gastroparesis.
Upper GI endoscopy: During this procedure, which is also called an esophagogastroduodenoscopy, a healthcare provider inserts an endoscope—a camera on a flexible tube—into the esophagus to see into the stomach. This test can help diagnose stomach cancer, GERD, and ulcers.
Tips for Keeping Your Stomach Healthy
Help your stomach function properly and decrease your risk of stomach-related health conditions with these tips:
Eat slowly and regularly: Taking time to chew your food aids digestion. It also helps avoid acid reflux you may get from overeating. If eating three meals causes acid reflux or discomfort, try eating four to five small meals. You can also try to stop eating two to three hours before bedtime.
Cut down on alcohol: Binge drinking can make your stomach overproduce acid, leading to painful ulcers and GERD.
Drink water: Make sure you're drinking water before and after meals. Water helps your stomach enzymes break down food so your body can absorb more nutrients.
Stop smoking: Smoking puts you at risk of developing stomach cancer. The habit can also lead to acid reflux that aggravates stomach ulcers.
Manage stress: Stress can make stomach ulcers worse, upset digestion, and change eating habits. Try destressing with mindfulness, yoga, regular exercise, or deep breathing.
A Quick Review
The stomach is an essential digestive system organ that is part of the GI tract. During digestion, your stomach uses muscle contractions and stomach acid to break down food it has received from the esophagus. The stomach then passes broken-down food to the small intestine. Digestion is important because breaking down food helps your body absorb nutrients. If the stomach isn't working properly or becomes damaged, you may experience heartburn, ulcers, indigestion, or stomach discomfort. You can try to keep your stomach healthy by eating slowly and at regular times and by drinking enough water. If you have concerns about the health or proper function of your stomach, visit a healthcare provider. They can help diagnose and treat any potential issue.
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