Anatomy of the StomachThe stomach is an organ of the digestive system. It is an expanded section of the digestive tube between the esophagus and small intestine. Its characteristic shape is well known. The right side of the stomach is called the greater curvature and the left the lesser curvature. The most distal and narrow section of the stomach is termed the pylorus - as food is liquefied in the stomach it passes through the pyloric canal into the small intestine.
The wall of the stomach is structurally similar to other parts of the digestive tube, with the exception that the stomach has an extra oblique layer of smooth muscle inside the circular layer, which aids in performance of complex grinding motions. In the empty state, the stomach is contracted and its mucosa and submucosa are thrown up into distinct folds called rugae; when distended with food, the rugae are "ironed out" and flat. The image above shows rugae on the surface of a dog's stomach.
If the lining of the stomach is examined with a hand lens, one can see that it is covered with numerous small holes. These are the openings of gastric pits which extend into the mucosa as straight and branched tubules, forming gastric glands.
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Republished with permission by Richard Bowen - Hypertexts for Biomedical Sciences