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The appendix has a mucosa resembling the colon but is heavily infiltrated with lymphocytes. Transition between the different types of epithelium occurs at the junction between the oesophagus and stomach; between the stomach and duodenum, between the ileum and caecum, and at the pectinate line of the anus. [1]
Gastric erosion occurs when the mucous membrane lining the stomach becomes inflamed. Specifically, the term "erosion" in this context means damage that is limited to the mucosa, which consists of three distinct layers: the epithelium (in the case of a healthy stomach, this is non-ciliated simple columnar epithelium), the basement membrane, and the lamina propria.
Diagram of the alkaline mucous layer in the stomach with mucosal defense mechanisms. The gastric mucosa is the mucous membrane layer of the stomach, which contains the gastric pits, to which the gastric glands empty. In humans, it is about one mm thick, and its surface is smooth, soft, and velvety.
A Cameron lesion is a linear erosion or ulceration of the mucosal folds lining the stomach where it is constricted by the thoracic diaphragm in persons with large hiatal hernias. [1] The lesions may cause chronic blood loss resulting in iron deficiency anemia ; less often they cause acute bleeding.
Pepsin is a protease that can digest and damage stomach cells. To prevent these disastrous effects, mucus and bicarbonate ions (HCO 3 −) are secreted by the foveolar cells. The mucus allows the acid at pH above 4 to penetrate lining, but below pH 4 (i.e. when acid is more concentrated) the acid cannot penetrate the mucus.
It is the innermost layer of the stomach. [5] It is affected by the hormone histamine, which signals it to release hydrochloric acid (HCl). Sub-mucosal layer – This layer consists of different vessels and nerves, ganglion neurons, and adipose tissue. It is the second layer of the stomach and supports the mucosa. [6]
The gastric mucosal barrier is the property of the stomach that allows it to safely contain the gastric acid required for digestion. If the barrier is broken, as by acetylsalicylic acid (ASA, aspirin) in acid solution, acid diffuses back into the mucosa where it can cause damage to the stomach itself.
Gastric pits are indentations in the stomach which denote entrances to 3-5 tubular gastric glands. [ 1 ] [ 2 ] They are deeper in the pylorus than they are in the other parts of the stomach. The human stomach has several million of these pits which dot the surface of the lining epithelium .