The fundus is a dome-shaped part of the stomach that stores gas from digestion. It can also hold food if the stomach becomes full.

The stomach is an important part of the digestive system. It stores and breaks down food before passing it through to the small intestine.

In this article, we look at the parts of the stomach and their different roles. We also discuss health conditions that can affect the stomach and provide tips for keeping the stomach healthy.

The stomach is part of the gastrointestinal (GI) tract and digestive system. It sits on the left side of the body in the upper abdomen.

The stomach is a curved, J-shaped organ that connects to the esophagus and small intestine. The esophagus is the tube that carries food and liquids from the mouth to the stomach, and the small intestine digests food further.

The three main functions of the stomach are:

  • storing food and releasing it into the small intestine at a steady rate
  • killing microorganisms with hydrochloric acid and releasing enzymes to digest proteins
  • breaking down food and mixing it with stomach acid to create a thick liquid

The parts of the stomach include:

  • Cardia: The cardia is the section of the stomach that connects to the esophagus. This is where food enters the stomach.
  • Fundus: The fundus is a dome-shaped section at the top of the stomach. It does not usually store food unless the stomach is full. The fundus stores any gas that is a byproduct of digestion.
  • Body: The body of the stomach stores food until it passes into the small intestine. When empty, the volume of the body is 50 milliliters, but it can expand to 1 liter when eating.
  • Antrum: The antrum is the lower section of the stomach. Here, strong contractions mix food with stomach acid to create a substance called chyme. The wave-like movements that the contractions produce push the chyme toward the pyloric sphincter.
  • Pylorus: The pylorus is a funnel-shaped section that controls the rate at which food empties from the stomach into the small intestine.

Chyme then passes into the duodenum, which is the first section of the small intestine. The chyme mixes with bile and digestive enzymes, and the small intestine begins to absorb nutrients.

The following health conditions can affect the stomach:

  • Stomach ulcers: A stomach ulcer is a sore in the stomach that can cause upper abdominal pain, which can sometimes be severe, and internal bleeding. It can occur due to bacterial infection or frequent use of nonsteroidal anti-inflammatory drugs (NSAIDs).
  • Gastroenteritis: Gastroenteritis is a temporary inflammation of the stomach that can cause diarrhea and vomiting.
  • Gastritis: Gastritis is the term for inflammation of the stomach lining. This can occur due to dietary and lifestyle factors, infection or trauma to the stomach, or certain diseases, such as autoimmune disorders. It can cause stomach pain, nausea, and loss of appetite.
  • Gastroesophageal reflux disease (GERD): GERD is a condition in which the contents of the stomach travel back up into the esophagus. GERD causes persistent symptoms, including heartburn and acid reflux.
  • Gastroparesis: Gastroparesis is a condition in which the muscles in the stomach do not work effectively to empty food into the small intestine. This delays digestion and can cause bloating, nausea, and a feeling of fullness.
  • Indigestion: Indigestion is the term for a group of symptoms that include feeling uncomfortably full, bloating, and stomach pain. Eating and drinking certain foods, stress, and some health conditions may cause indigestion.
  • Stomach cancer: Abnormal cell changes in the lining of the stomach may lead to a person developing stomach cancer. The symptoms of stomach cancer include loss of appetite, unexplained weight loss, and abdominal pain.

People can take steps to promote good stomach health. These include:

  • increasing fiber intake by including plenty of vegetables and fruits in the diet
  • eating probiotic and fermented foods, such as kefir, probiotic yogurt, kimchi, sauerkraut, and pickled ginger
  • practicing good sleep hygiene, as better sleep may help lower the risk of obesity and support better gut health
  • staying active with regular movement and exercise
  • practicing relaxation techniques to manage stress, which may help prevent or treat conditions such as heartburn
  • treating any mental health conditions, such as anxiety or depression, to help support the gut, as the gut and brain have a close connection

Anyone with persistent or worsening symptoms that may be a sign of an underlying condition should speak with a doctor as soon as possible. Examples of these symptoms include:

  • loss of appetite
  • fatigue
  • nausea
  • vomiting
  • constipation
  • diarrhea
  • bloating or gas
  • swelling of the abdomen
  • heartburn or indigestion
  • slow growth in children
  • abdominal pain, discomfort, or cramps
  • the feeling of needing a bowel movement after emptying the bowels
  • mucus or blood in the stool
  • unexplained weight loss
  • feeling full after not eating much
  • very dark or black stools
  • yellowing of the skin or eyes, known as jaundice

The stomach sits in the upper left side of the abdomen. Food and liquids travel down the esophagus to enter the stomach. The stomach starts digesting food before it passes into the small intestine.

The fundus is a section of the stomach that stores gas from digestion. It can also hold food when the stomach is full.

Various health conditions such as gastritis, gastroparesis, and stomach ulcers can all affect the stomach.

Eating certain types of foods, managing stress, and maintaining a moderate weight can all help support good gut health.

Anyone experiencing persistent symptoms relating to the stomach should consult a doctor, who can help determine the underlying cause.