Endothelium: The Lining of Your Blood Vessels - Structure & Function

The internal lining of the cardiovascular system is formed by the endothelium, which is a type of simple squamous epithelium. Endothelial cells are flat, polygonal cells that line the inner surface of blood vessels, including arteries, veins, and capillaries. These cells play a crucial role in regulating blood flow, vascular permeability, and immune responses.