And so we say that veins have a high compliance. So veins behave very differently than arteries. When they experience blood flow, the blood pushes on the walls, but the walls cannot actually push back as well. And so what happens is this increases and expands the cross sectional area of our vein and therefore increases the amount of volume that can pass along that given vein. It also ensures that there isn't a build up of pressure within our veins. And that's exactly why in arteries we have a high pressure because the walls can easily push back.