What is the specific name given to the epithelial lining of blood and lymph vessels or the heart?

The specific name given to the epithelial lining of blood vessels, lymph vessels, and the heart is "endothelium." The endothelium is a thin layer of cells that provides a smooth lining for the interior surface of blood and lymphatic vessels, as well as the heart chambers. Its primary functions include regulating vascular tone, controlling the passage of materials and the transit of white blood cells into and out of the bloodstream, and maintaining blood fluidity. The health of the endothelium is crucial for the overall cardiovascular system, influencing processes such as inflammation, clotting, and vascular remodeling.