What documents do I need to present to reenter the United States? If seeking to enter the United States after temporary travel abroad, you will need to present a valid, unexpired âgreen cardâ (Form I-551, Permanent Resident Card).
Brain Tour. 2. Supply lines. Your brain is nourished by one of your body's richest networks of blood vessels. With each heartbeat, arteries carry about 20 to 25 percent of your blood to your brain, where billions of cells use about 20 percent of the oxygen and fuel your blood carries. When you are thinking hard, your brain may use up to 50 percent of the fuel and oxygen.
Blood Vessels: Arteries: These are large blood vessels that take oxygenated blood away from the heart to be distributed throughout the body. The aorta is the body's largest artery. Veins: These blood vessels take deoxygenated blood from around the body back to the heart and lungs to be oxygenated.Capillaries: These tiny blood vessels are where the exchange of oxygen and nutrients take place. The nutrients and oxygen are exchanged for wastes that are taken from the cells.eins: These blood vessels take deoxygenated blood from around the body back to the heart and lungs to be oxygenated. Capillaries: These tiny blood vessels are where the exchange of oxygen and nutrients take place.