Anatomy and physiology of the stomach
The stomach is part of the digestive system and is connected to the:
- esophagus – a tube-like organ that connects the mouth and throat to the stomach. The area where the esophagus joins the stomach is called the gastroesophageal (GE) junction.
- small intestine (small bowel) – a long tube-like organ that extends from the stomach to the colon (large intestine or large bowel). The first part of the small intestine is called the duodenum, and it is this part that is connected to the stomach.
The stomach is surrounded by a large number of
Layers of the stomach wall @(Model.HeadingTag)>
The stomach is made up of several layers of tissue:
- The mucosa (mucous membrane) is the inner lining of the stomach. When the stomach is empty the mucosa has a ridged appearance. These ridges (rugae) flatten out as the stomach fills with food.
- The next layer that covers the mucosa is the submucosa. It is made up of connective tissue that contains larger blood and lymph vessels, nerve cells and fibres.
- The muscularis propria (or muscularis externa) is the next layer that covers the submucosa. It is the main muscle of the stomach and is made up of 3 layers of muscle.
- The serosa is the fibrous membrane that covers the outside of the stomach. The serosa of the stomach is also called the
The stomach has 3 main functions:
- temporary storage for food, which passes from the esophagus to the stomach where it is held for 2 hours or longer
- mixing and breakdown of food by contraction and relaxation of the muscle layers in the stomach
- digestion of food
The mucosa contains specialized cells and glands that produce hydrochloric acid and digestive enzymes to help digest food. The mucosa in the cardiac and pyloric regions of the stomach release mucus that helps protect the lining of the stomach from the acid produced for digestion. Other specialized cells in the mucosa of the pylorus release the
Food is broken down into a thick, acidic, soupy mixture called chyme. The pyloric sphincter relaxes once chyme formation is complete. Chyme then passes into the duodenum. The duodenum plays a big role in absorption of the food we eat. The stomach does not play a big role in absorption of food. It only absorbs water, alcohol and some drugs.
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