Stomach: Anatomy, Function, Capacity, Diseases, Diet


Stomach anatomy

The stomach is a muscular, J-shaped organ located in the upper abdomen, between the esophagus and the small intestine. It has four main regions:

  1. Cardia: The uppermost part of the stomach where the esophagus connects to the stomach.
  2. Fundus: The rounded, upper portion of the stomach that lies above the level of the cardia. The fundus expands as it fills with food.
  3. Body: The main central region of the stomach where food is mixed and ground up. The body is the largest part of the stomach and can expand and contract as needed.
  4. Pylorus: The lower part of the stomach that connects to the small intestine. It contains a ring of muscle called the pyloric sphincter that controls the release of food from the stomach into the small intestine.

The stomach is lined with a specialized type of tissue called mucosa, which contains glands that secrete gastric juices and enzymes to aid in digestion. The gastric glands in the mucosa produce hydrochloric acid, pepsinogen, and mucus. The hydrochloric acid helps to break down food and kill bacteria, while the pepsinogen is converted to pepsin, an enzyme that breaks down proteins.

The walls of the stomach are made up of three layers of muscle: the outer longitudinal layer, the middle circular layer, and the inner oblique layer. These muscles work together to mix and grind food into a semi-liquid substance called chyme.

Overall, the complex anatomy of the stomach is essential for the digestive process, and allows food to be broken down into nutrients that can be absorbed into the bloodstream and used by the body.

Stomach capacity (storage volume) by age in ml

Stomach capacity (storage volume) can vary depending on a person’s age, gender, and individual differences in body size and weight. Here is a general guideline for stomach capacity by age in milliliters (ml):

  • Newborn at birth: 10-20 mL
  • 1 week: 30-90 mL
  • 1 month: 90-150 mL
  • 1 year: 200-350 mL
  • 2 years: 500 mL
  • 10 years: 750-900 mL
  • 16 years: 1,500 mL
  • Adult: 1.5-3 or up to 4 liters of food

It is important to note that these values are approximate and can vary widely depending on an individual’s body size and weight. Additionally, stomach capacity can also be affected by factors such as meal frequency and composition.

Physiology of stomach

The stomach is a key organ in the digestive system, responsible for breaking down food into smaller particles and preparing it for absorption in the small intestine. Its physiology involves several processes, including:

  1. Secretion of gastric juices: The stomach secretes gastric juices consisting of hydrochloric acid, pepsinogen, and mucus. Hydrochloric acid helps to break down food, kill bacteria, and create an acidic environment for enzymes to function. Pepsinogen is converted to pepsin, an enzyme that breaks down proteins.
  2. Mixing and grinding of food: The muscular walls of the stomach contract and relax in a coordinated manner to mix and grind food with gastric juices into a semi-liquid substance called chyme.
  3. Emptying of chyme: The pyloric sphincter, located at the bottom of the stomach, regulates the release of chyme into the small intestine.
  4. Hormonal regulation: Hormones such as gastrin, secretin, and cholecystokinin (CCK) are released by the stomach and small intestine to regulate the secretion of gastric juices and the emptying of chyme into the small intestine.
  5. Protection of the stomach lining: The stomach is protected from the acidic environment by a layer of mucus that coats the inner lining of the stomach.
  6. Absorption of certain substances: Small amounts of alcohol, water, and some drugs can be absorbed through the stomach lining.

The physiology of the stomach is complex and involves the coordination of various processes and hormones. It plays a crucial role in the digestion and absorption of nutrients and other substances from the food we eat.

What is digestion?

Digestion is the process by which our body breaks down food into smaller molecules that can be absorbed and used for energy and other biological functions. It involves several organs and enzymes working together in a coordinated manner. The process of digestion can be divided into two main stages: mechanical and chemical digestion.

  1. Mechanical Digestion: It involves the physical breakdown of food into smaller particles by chewing, churning of the stomach, and the action of the small intestine. The food is broken down into smaller pieces, increasing its surface area and making it easier for digestive enzymes to work.
  2. Chemical Digestion: It involves the breakdown of food into smaller molecules by enzymes and other substances. It begins in the mouth with the action of enzymes in saliva, and continues in the stomach and small intestine. The enzymes break down carbohydrates, proteins, and fats into their component parts, which can then be absorbed by the body.

The major organs involved in digestion are the mouth, esophagus, stomach, small intestine, pancreas, liver, and large intestine. The mouth is responsible for the initial mechanical and chemical digestion of food, while the esophagus transports food to the stomach. The stomach secretes gastric juices that break down proteins and other components of the food, and the small intestine is responsible for the majority of chemical digestion and absorption of nutrients.

The pancreas secretes digestive enzymes into the small intestine, and the liver produces bile that helps break down fats. The large intestine absorbs water and electrolytes from the remaining undigested food, and solid waste is eliminated from the body as feces.

Overall, the process of digestion is essential for the body to obtain nutrients from the food we eat, and to eliminate waste products efficiently.

How long does it take for food to pass through the stomach?

The amount of time it takes for food to pass through the stomach can vary depending on several factors, including the type and quantity of food consumed, individual differences in digestive function, and the presence of any underlying medical conditions. Generally, it takes between 4 to 6 hours for food to pass through the stomach and into the small intestine. However, some foods, such as high-fat or high-fiber meals, may take longer to digest and pass through the stomach. It is important to note that the digestion process is complex and involves multiple organs and systems working together to break down and absorb nutrients from food.

See also, how long it takes for food to be pooped out at the article of here.

What are the common diseases and conditions that affect the stomach?

There are several diseases and conditions that can affect the stomach, including:

  1. Gastroesophageal Reflux Disease (GERD): A chronic condition where the stomach acid flows back into the esophagus, causing heartburn and other symptoms.
  2. Peptic Ulcer Disease: A sore or hole in the lining of the stomach or duodenum, commonly caused by the bacteria H. pylori or prolonged use of nonsteroidal anti-inflammatory drugs (NSAIDs).
  3. Gastritis: Inflammation of the stomach lining, caused by a variety of factors including H. pylori infection, excessive alcohol consumption, and prolonged use of NSAIDs.
  4. Gastroparesis: A condition where the stomach muscles don’t work properly, resulting in delayed gastric emptying and symptoms such as nausea, vomiting, and bloating.
  5. Stomach Cancer: A malignant tumor that develops in the lining of the stomach, often with no early symptoms.
  6. Functional Dyspepsia: A condition where the stomach and digestive system function abnormally, leading to symptoms such as stomach pain, bloating, and nausea.
  7. Gastrointestinal Stromal Tumor (GIST): A rare type of tumor that can occur in the stomach or other parts of the digestive system.
  8. Zollinger-Ellison Syndrome: A rare disorder where tumors in the pancreas or duodenum produce excessive amounts of the hormone gastrin, leading to increased production of stomach acid.
  9. Helicobacter pylori (H. pylori) Infection: A bacterial infection that can cause ulcers and inflammation in the stomach lining.
  10. Hiatal Hernia: A condition where a part of the stomach pushes up through the diaphragm into the chest cavity, causing symptoms such as heartburn and chest pain.
  11. Gastric Outlet Obstruction: A condition where the stomach is partially or completely blocked, causing symptoms such as nausea, vomiting, and abdominal pain.
  12. Bezoars: A mass of undigested material that accumulates in the stomach, often caused by ingesting hair, plant material, or other foreign objects.

These are just a few examples of the many conditions that can affect the stomach. It is important to see a gastroenterologist if you experience persistent or severe stomach symptoms, as they can help diagnose and treat underlying conditions.

How are stomach problems diagnosed and treated?

The diagnosis and treatment of stomach problems depend on the underlying cause of the symptoms. Here are some common diagnostic and treatment options for stomach problems:


  1. Medical History and Physical Exam: Your healthcare provider will likely ask about your symptoms and medical history, and perform a physical exam to check for any signs of abdominal tenderness, bloating, or distention.
  2. Laboratory Tests: Blood tests can be used to check for signs of infection, inflammation, or liver or kidney function. Stool samples may also be tested for signs of infection or digestive issues.
  3. Imaging Tests: Imaging tests such as X-rays, CT scans, or ultrasounds can provide a detailed view of the digestive system and help identify any abnormalities or blockages.
  4. Esophagogastroduodenoscopy: A procedure in which a flexible tube with a camera is inserted through the mouth and into the stomach and small intestine, allowing the gastroenterologist to view the digestive system and take tissue samples for analysis.


Treatment options for stomach problems depend on the underlying cause of the symptoms. Examples include:

  • Medications: Antacids, proton pump inhibitors, antibiotics, or anti-inflammatory drugs may be prescribed to treat conditions such as gastroesophageal reflux disease, ulcers, or H. pylori infection.
  • Lifestyle Changes: Changes in diet, exercise, and stress management can help alleviate symptoms of conditions such as functional dyspepsia or gastritis.
  • Surgery: In some cases, surgery may be required to remove blockages or repair damage to the digestive system.

It is important to work closely with your gastroenterologist to determine the underlying cause of your stomach problems and develop an appropriate treatment plan. Early diagnosis and treatment can help prevent complications and improve outcomes.

What are some dietary and lifestyle changes that can help prevent stomach problems?

There are several dietary and lifestyle changes that can help prevent stomach problems. Here are some tips:

  1. Eat a Healthy Diet: A diet rich in fruits, vegetables, whole grains, lean proteins, and low-fat dairy products can help promote digestive health. Avoiding high-fat, spicy, or fried foods may also help prevent stomach problems.
  2. Stay Hydrated: Drinking plenty of water and other fluids can help prevent constipation and promote regular bowel movements, which can help prevent digestive issues.
  3. Manage Stress: Stress can affect digestive function, so finding ways to manage stress such as meditation, or exercise may help prevent stomach problems.
  4. Exercise Regularly: Regular physical activity can help promote regular bowel movements and prevent constipation, which can contribute to stomach problems.
  5. Don’t Smoke: Smoking can increase the risk of developing stomach problems such as ulcers, so quitting smoking can help prevent these issues.
  6. Limit Alcohol and Caffeine: Consuming excessive amounts of alcohol or caffeine can irritate the stomach lining and contribute to stomach problems.
  7. Maintain a Healthy Weight: Being overweight or obese can increase the risk of developing digestive issues, so maintaining a healthy weight through a balanced diet and regular exercise may help prevent stomach problems.
  8. Practice Good Food Hygiene: Wash your hands before handling food, ensure that food is cooked thoroughly, and avoid eating food that is past its expiration date to prevent the growth of harmful bacteria. This way you will avoid food poisoning.
  9. Avoid Overeating: Eating too much can put pressure on the stomach and increase the risk of developing acid reflux or heartburn.
  10. Chew Food Thoroughly: Chewing food thoroughly can help aid digestion and prevent stomach problems such as indigestion.
  11. Avoid Eating Before Bedtime: Eating late at night can increase the risk of developing acid reflux or heartburn, so it’s best to avoid eating within 2-3 hours of bedtime.
  12. Avoid Trigger Foods: Certain foods may trigger stomach problems in some individuals, so it may be helpful to keep a food diary and track any foods that seem to cause digestive issues.

How can I contact gastroenterologist Dr. Zavos for an appointment?

Dr. Chris Zavos is a board-certified gastroenterologist and hepatologist, located in Thessaloniki Greece, and specifically in Kalamaria suburb, about 7 kilometres (4 miles) southeast of downtown Thessaloniki. His private office is at: Fanariou 8 street (near Aigaiou and Adrianoupoleos avenues), Kalamaria (Thessaloniki), Greece.

Thessaloniki International Airport is only 10 km away from his private office in Kalamaria and can be reached by taxi within 13 minutes from the airport.

Dr. Chris Zavos performs endoscopies at Bioclinic private hospital in downtown Thessaloniki (Mitropoleos 86 street).

You can contact Dr. Zavos at phone numbers: (+30)-6976596988 and (+30)-2311283833, or you can email him at Dr. Zavos responds to Greek and English languages.

Last update: 26 September 2023, 18:59


Gastroenterologist - Hepatologist, Thessaloniki

PhD at Medical School, Aristotle University of Thessaloniki, Greece

PGDip at Universitair Medisch Centrum Utrecht, The Netherlands

Ex President, Hellenic H. pylori & Microbiota Study Group