On average, your body has about 5 liters
of blood continually traveling through it by
way of the circulatory system. The heart,
the lungs, and the blood vessels work
together to form the circle part of the
circulatory system.

The pumping of the heart forces the blood
through to every cell in the body.  It is a
masterful organ that moves oxygen, food,
and hormones and water to the cells and
carries away carbon dioxide, urea and
waste products to the lungs, liver, kidneys
and sweat glands.