The Heart and Major Vessels
When you gain a pound of fat, your body creates seven miles of blood vessels.
Check Out This Month's Most Popular Topic
Key Facts In This Video
The back of the heart is known as its "base". (1:26)
Veins returning from the lungs into the left side of the heart are the only veins that carry oxygenated blood. (3:37)
There are four valves leading to or from the heart. (5:01)