Endothelium

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File:Anatomy artery.png
Diagram showing the location of endothelial cells
File:Microvessel.jpg
Endothelial cells, which form the tunica intima, encircle an erythrocyte (E).

The endothelium is the thin layer of cells that lines the interior surface of blood vessels,[1] forming an interface between circulating blood in the lumen and the rest of the vessel wall. These cells are called endothelial cells. Endothelial cells line the entire circulatory system, from the heart to the smallest capillary. These cells reduce turbulence of the flow of blood allowing the fluid to be pumped farther.

Endothelial tissue is a specialized type of epithelium tissue (one of the four types of biological tissue in animals). More specifically, it is simple squamous epithelium.

The endothelium normally provides a non-thrombogenic surface because it contains heparan sulfate which acts as a cofactor for activating antithrombin III, a protease that cleaves several factors in the coagulation cascade.

Terminology

The foundational model of anatomy makes a distinction between endothelial cells and epithelial cells on the basis of which tissues they develop from and states that the presence of vimentin rather than keratin filaments separate these from epithelial cells.[2]

Endothelium of the interior surfaces of the heart chambers are called endocardium. Both blood and lymphatic capillaries are composed of a single layer of endothelial cells called a monolayer.

Function

Endothelial cells are involved in many aspects of vascular biology, including:

In some organs, there are highly differentiated endothelial cells to perform specialized 'filtering' functions. Examples of such unique endothelial structures include the renal glomerulus and the blood-brain barrier.

Pathology

Endothelial dysfunction, or the loss of proper endothelial function, is a hallmark for vascular diseases, and is often regarded as a key early event in the development of atherosclerosis. Impaired endothelial function is often seen in patients with coronary artery disease, diabetes mellitus, hypertension, hypercholesterolemia, as well as in smokers. Endothelial dysfunction has also been shown to be predictive of future adverse cardiovascular events. One of the main mechanisms of endothelial dysfunction is the diminishing of nitric oxide, often due to high levels of asymmetric dimethylarginine, which interfere with the normal L-arginine-stimulated nitric oxide synthesis. The most prevailing mechanism of endothelial dysfunction is an increase in reactive oxygen species, which can impair nitric oxide production and activity via several mechanisms.[3] The signalling protein ERK5 is essential for maintaining normal endothelial cell function [4].

See also

References

Notes

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Bibliography

  • Molecular Biology of the CELL, 4th edition, Alberts et al., 2002

External links

bs:Endotel

bg:Ендотел ca:Endoteli cs:Endotel de:Endothel es:Endotelio eo:Endotelio fr:Endothélium it:Tessuto endoteliale la:Endothelium ml:എൻഡോതീലിയം nl:Endotheel ja:血管内皮 nds:Endothel pl:Śródbłonek pt:Endotélio ru:Эндотелий sk:Endotel sr:Ендотел fi:Endoteeli sv:Endotel uk:Ендотелій vi:Tế bào nội mô

zh:內皮細胞
  1. Endothelium at Dorland's Medical Dictionary
  2. "FMA". Retrieved 2008-12-12. 
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