The endothelium is crucial and susceptible to injury from chemical irritants and mechanical stress.

“so the endothelium as you know is the Single Cell lining that is the innermost part of the arterial and arterial wall so this is a pretty special organ um again it's it's it's a bit naive but understandable that people just think of arteries as tubes um they're much more complicated than that they have many layers to them but this particular layer is unusually important has an outsized importance because it is the one that's in contact with the luminal side right where the blood is flowing in the tube and anything that injures that has significant consequences”