And that's exactly why when the blood flows through our vein, when it expands, it remains in that shape because it doesn't have all of that smooth muscle to recoil it back into place. So that's exactly why, unlike the arteries, these don't actually have such a high resistance, and they can expand and carry much more blood, much more volume of blood than our arteries. In fact, the veins together carry about 60% to 65% of the total volume of blood. The rest is carried by the capillaries, and a small portion is carried by our arteries or a relatively small portion. Now, arteries actually have it pretty easy because when arteries expand from the heart and they travel to the bottom of the body, they are moving with the force of gravity so in the same direction that the force of gravity actually acts. However, when those venues and veins leave the capillaries in the bottom portion of our body, they have to move up to the harm and against the force of gravity.