Circulatory system the areas above the heart) and the inferior vena cava (roughly speaking from areas below the heart). These two great vessels empty into the right atrium of the heart. The heart itself is supplied with oxygen and nutrients through a small "loop" of the systemic circulation and derives very little from the blood contained within the four chambers. The general rule is that arteries from the heart branch out into capillaries, which collect into veins leading back to the heart. Portal veins are a slight exception to this. In humans the only significant example is the hepatic portal vein which
Vasa vasorum and the tunica media, causing them to need a more extensive vasa vasorum. A later method of scanning is optical coherence tomography that also gives 3D imaging. The vasa vasorum are found in large vein and arteries such as the aorta and its branches. These small vessels serve to provide blood supply and nourishment for tunica adventitia and outer parts of tunica media of large vessels. Vasa vasorum The vasa vasorum is a network of small blood vessels that supply the walls of large blood vessels, such as elastic arteries (e.g. aorta) and large veins (e.g. venae cavae). The name