| A | B |
| heart | organ that pumps blood throughout the body |
| artery | blood vessel that carries blood away from the heart |
| vein | blood vessel that carries blood back to the heart |
| aorta | largest artery in the body |
| atria | receiving chambers of the heart |
| ventricles | chamber that pumps blood out of the heart |
| capillary | smallest kind of blood vessel |
| blood | carries oxygen and nutrients to the rest of the body |
| red blood cells | cells that carry oxygen in the blood |
| white blood cells | cells that protect the body against foreign substances like germs |