The circulatory system includes the heart, arteries, veins, capillaries,
spleen, and the urinary tract. The urinary tract consists of the kidneys,
ureters, bladder, and the urethra. The spleen is not included in the
illustrations on this page, because it is also part of the lymphatic system
and is included in that discussion.
The circulatory system circulates blood throughout our bodies. The heart first
pumps the blood to the arteries. It continues to flow until it reaches the tiny
capillaries where it gives our body nutrients and other important things needed
to maintain our health. From there it returns to the heart through our veins.
The spleen filters the blood and stores red blood cells. The kidneys are
also filters and dispose of the waste and excess water by sending it to the
bladder where it is held until released.