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The intestinal epithelium is the single cell layer that forms the luminal surface (lining) of both the small and large intestine (colon) of the gastrointestinal tract. Composed of simple columnar epithelium its main functions are absorption, and secretion.
The gut-associated lymphoid tissue lies throughout the intestine, covering an area of approximately 260–300 m 2. [5] In order to increase the surface area for absorption, the intestinal mucosa is made up of finger-like projections (), covered by a monolayer of epithelial cells, which separates the GALT from the lumen intestine and its contents.
In the oesophagus, pharynx and external anal canal the epithelium is stratified, squamous and non-keratinising, for protective purposes. In the stomach, the epithelium is simple columnar, and is organised into gastric pits and glands to deal with secretion. [1] In the small intestine, epithelium is simple columnar and specialised for absorption.
In the respiratory tract, from the trachea to the terminal bronchioles, the lining is of respiratory epithelium that is ciliated. [8] The cilia are hair-like, microtubular-based structures on the luminal surface of the epithelium. On each epithelial cell there are around 200 cilia that beat constantly at a rate of between 10 and 20 times per ...
The gastrointestinal tract is composed of numerous cell types that are important for immune activation and barrier surface defenses. The gastrointestinal epithelium is composed of enterocytes, goblet cells, Paneth cells, enteroendocrine cells, tuft cells, and stem cells.
Because the epithelium is often under external stress and is somewhat delicate, the lamina propria hosts many immune cells. [4] In the intestinal tract the immune system must have tolerance to the normal intestinal flora, yet respond to pathogenic microorganisms. Imbalance of this causes inflammation diseases such as inflammatory bowel disease ...
System Tissue Epithelium Subtype; circulatory: blood vessels: Simple squamous: endothelium: digestive: ducts of submandibular glands: simple columnar - digestive ...
These cells migrate into the intestinal epithelium as effector or tissue-resident memory T cells. In mice, up to 50% of these IELs can express CD8αα homodimer, which they acquire in the intestinal epithelium after external stimuli such as TGF-β, IFN-γ, IL-27 and retinoic acid. Function of TCRαβ + CD4 + CD8αα + IELs is unclear. Even ...