And as a result of the elastic nature of these blood vessels, it causes them to actually recoil. And when they recoil, that is exactly what moves that blood through the rest of our arteries. So this is how blood flows inside the artery. Now, what about our veins? Well, just like arteries come in different sizes, veins also come in different sizes. The smallest vein is called a Venuel and the largest vein in our body is called the vena cava.