So the cells, tissues and organs pick up the nutrients and electrolytes that they actually need to survive. They also pick up our oxygen and they give off the carbon dioxide as well as our waste products. And then our deoxy and blood travels into the tiny venues, then into the veins. And all these veins basically converge into a single vein known as the vena cava. Now, the superior vena cava is basically the upper vein that carries all that de oxygen blood away from the upper organs. This is a superior vena cava.