Cheap Nike Air Max 90
Friends link: nike pas cher
nike pas cher
nike pas cher
nike pas cher
nike pas cher
nike pas cher
nike pas cher
nike pas cher
nike pas cher
nike pas cher
nike pas cher
timberland pas cher
timberland pas cher
nike pas cher
Nike Tn Pas Cher Nike BasketBalltn pas cher
new balance pas cher
air max 90 pas cher
air max pas cher
nike pas cher
air jordan pas cher
air max 90 pas cher
timberland homme pas cher
nike free running pas cher
bottes timberland pas cher
puma pas cher femme
air max 90 pas cher
nike free run pas cher
nike tn requin pas cher
puma pas cher

How Do Veins Work?

Blood flows through a system of blood vessels, which are veins and arteries. Arteries carry blood rich in oxygen from your heart to all regions of the body. The function of veins is to transport the blood back to the heart. In order for veins to work, the valves must close all the way to prevent backflow of blood. When the muscles in your calf contract; blood is squeezed from the veins. When the muscles in your calf relax, the valves in the veins temporarily close to prevent the blood from flowing away from the heart, in the wrong direction!

In your legs, there are 3 types of veins; superficial, perforating, and deep veins. Think of the perforating veins as connecting the superficial veins to the deep veins. If you are standing, superficial veins run vertically, just beneath the surface of the skin and are often times visible to the naked eye. Superficial veins are responsible for transporting as little as 10% of the blood in the legs. The 10% of blood carried in the superficial veins flow directly into the perforating veins. The perforating veins run perpendicular to superficial veins and again, their function is to connect the superficial veins to the deep veins. Deep veins are located deep within the muscle of your leg and run parallel to superficial veins. Deep veins are responsible for transporting as much as 90% of the blood in your legs back to your heart.