The stomach is a muscular organ that holds and breaks down food. The stomach contains gastric juice, a complex digestive fluid that digests foods, helps the body absorb nutrients and some drugs, such as aspirin. The stomach also helps the digestive system break down and absorb fats and proteins.
The stomach has four main regions: the cardia, fundus, body and pylorus. The cardia is the first part of the stomach and connects to the esophagus. It includes the cardiac sphincter, a thin ring of muscle that helps prevent stomach contents from going back up into the esophagus. The fundus is the top, rounded area of the stomach. Below the fundus is the body, which is the largest and main area of the stomach. The pylorus is the funnel-shaped area at the bottom of the stomach that connects to the small intestine. It contains the pyloric sphincter, a thick ring of muscle that controls stomach emptying.
Stomach acid destroys bacteria in the mouth and throat that may be causing infections, and it breaks down proteins. The lining of the stomach is made of epithelium, which secretes a protective layer of alkaline mucus. A vast number of gastric pits dot the surface of the epithelium, giving it the appearance of a well-used pincushion. Each gastric pit is a small sac (villus) that contains a gastric gland that secretes a digestive fluid called gastric juice.
When food is eaten, the stomach walls tighten and expand to churn the food and mix it with the gastric juice. The chyme, or broken-down food, is then emptied into the first part of the small intestine, called the duodenum.
Most stomach cancers begin in the layer of cells that produces stomach acid. Less common types of stomach cancer, such as gastrointestinal stromal tumors and neuroendocrine tumors, start in different cell types within the stomach.
A large amount of fat in the abdomen is a risk factor for developing stomach cancer. There are two types of belly fat: subcutaneous and visceral. Subcutaneous fat is located just under the skin, and it is noticeable and often causes a dimpled appearance in the abdomen, hips and buttocks, similar to cellulite. Visceral fat is deeper than subcutaneous fat, and it is found inside the abdominal cavity.
The best way to reduce stomach fat is to eat a balanced diet that contains complex carbohydrates, soluble fibres, lean protein and healthy fats. Avoid consuming too much sugar, and quit smoking and drinking alcohol. Regular exercise can also help.