Vein Facts

Veins are pipes in the body for carrying blood back to the heart.
Unlike arteries, most veins carry ‘used’ blood back to the heart — the body cells have taken the oxygen they need from the blood, so it is low in oxygen.
When blood is low in oxygen, it is a dark, purplish blue color — unlike the bright red of the oxygenated blood carried by the arteries.
The only veins that carry oxygenated blood are the four pulmonary veins, which carry blood from the lungs the short distance to the heart.
The two largest veins in the body are the vena cavae that flow into the heart from above and below.
Inside most veins are flaps that act as valves to make sure that the blood only flows in Muscle one direction.
The blood in veins is pumped by the heart, but the blood pressure is much lower than in arteries and vein walls do elastic layer.
Unlike arteries, veins collapse not need to be as strong, when empty.
Blood is helped through the veins by pressure that is placed on the vein walls by the surrounding muscles.

This entry is filed under Interesting Facts.