The stomach is a J-shaped hollow organ present in the gastrointestinal tract of humans and other vertebrates (some invertebrates as well). It is a saclike expanding structure found between the oesophagus and small intestine. It is a digestive organ that is involved in secondary digestion, chewing, storage and mechanical distribution of food before passing it down to the small intestine.
Here is a diagrammatic representation of the transverse section (ts) of the stomach that shows the layers and inner linings of the organ.
TS of Stomach
Layers of the Stomach – Explained
- Mucosa: It is the innermost layer of the stomach lining. The mucosal layer is composed of one or more layers of epithelial cells with a layer of loose connective tissue under it called the lamina propria. It contains specialised cells that secrete mucus. It also contains mucosal glands that secrete the digestive enzyme pepsin and HCl.
- Submucosa: It is a thin layer of dense irregular connective tissues that supports the mucosal membrane and also forms a connection with the muscularis membrane. It contains blood vessels, lymphatic vessels and nerves. It also has submucosal glands that secrete mucus.
- Muscularis: The muscular layer is a layer of smooth muscles that lie next to the submucosal layer. It consists of three layers of muscular fibres – outer longitudinal, middle circular and inner oblique. The main function of this layer is to help in the peristaltic movements and contractions of the alimentary canal. It is the thickest layer of the stomach present and hence the maximum amount of peristalsis occurs here.
- Serosa: The serosa or serous membrane is the outermost layer of the stomach lining that is made up of layers of connective tissue. It is in continuation with the peritoneal layer of the abdominal cavity.
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