Aluminum Grades Series 7xxx. Zinc, in amounts of 1 to 8% is the major alloying element in 7xxx series aluminum alloys (7075, 7050, 7049, 710.0; 711.0 etc.), and when coupled with a smaller percentage of magnesium results in heat-treatable alloys of moderate to very high strength.
We previously learned that arteries carry blood away from the heart and that veins carry blood toward the heart. This idea holds true here because we see that the pulmonary arteries are carrying blood away from the heart and the pulmonary veins are carrying blood to the heart. The interesting thing is that in most areas of the body, veins carry blood that is low in oxygen and arteries usually carry blood that's rich in oxygen.
Simply the heart, a big muscle, is connected to a series of tubes, the arteries and the veins, which carry blood to the various parts of the body. Arteries carry the blood away from the heart, while veins bring blood back to the heart. The arteries are connected to the veins via very small vessels called capillaries. Electrical and chemical signals to the heart cause it to pump the blood into the arteries. Further, a number factors can cause the blood vessels to expand (dilate) or contract. In doing so they can increase or decrease the amount of effort the heart needs to put forth to deliver the blood.