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. The question is, what exactly allows the veins to move that blood against the force of gravity? And what keeps that blood from actually flowing back down those veins? Remember, veins do not actually have a thick layer of smooth muscles.