First 214 words of the document:
Circulation is for getting glucose and other nutrients, and oxygen to every cell in the
body. It also carries waste products like carbon dioxide and urea so they can be
The heart has 2 pumps, the right side pumps deoxygenated blood to the lungs to
collect oxygen and remove carbon dioxide, and the left side pumps oxygenated
blood around the body.
Arteries carry blood away from the heart at high blood pressure.
Normally arteries carry oxygenated blood and veins carry deoxygenated blood, but
the exceptions are the pulmonary artery which takes deoxygenated blood from the
heart to the lungs, and the pulmonary vein, which takes oxygenated blood from the
lungs to the heart.
Arteries split off into arterioles and capillaries to take blood to every cell.
Veins collect used blood and carry it back to the heart at low pressure.
All Mammals and birds have a double circulation system (as described above). Fish
only have a single circulation system, the blood goes straight from the heart to the
lungs and then to the rest of the body, it's only pumped once. Worms have 5 pairs
of hearts and flat worms have no circulatory system.