Endothelium

Endothelium is a thin layer of simple squamous cells that lines the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel wall.

Function

Endothelial cells form the barrier between vessels and tissue and control the flow of substances and fluid into and out of a tissue. The endothelium of the arterial wall secretes endothelin, a potent vasoconstrictor, in response to several stimuli such as hypoxia (low oxygen levels), physical stress and inflammation.

Structure

Endothelial cells are flat and aligned in the direction of fluid flow. They have a unique shape when viewed under a microscope - elongated and flat, this shape allows for the efficient flow of blood over their surface.

Role in Disease

Endothelial dysfunction, or the improper functioning of the endothelial layer, is a hallmark for vascular diseases, and is often a key early event in the development of atherosclerosis. Impaired endothelial function, causing hypertension and thrombosis, may occur in the systemic arteries and veins in the setting of hypercholesterolemia, diabetes or hypertension and atherosclerosis.

See Also

• Vascular endothelial growth factor
• Endothelial progenitor cell
• Endothelial microparticles

References

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Endothelium

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