| A | B |
|---|
| white blood cells | help body fight germs |
| red blood cells | carry oxygen |
| valves | keep blood from flowing backward in heart |
| ventricles | bottom chambers of heart |
| veins | blood vessels carrying blood back to heart |
| capillaries | smallest blood vessels |
| arteries | blood vessels carrying blood away from heart |
| circulatory system | transport system that carries food and oxygen to cells |
| blood | liquid with cells and other solids in it |
| heart | muscle that pumps blood |
| atrium | upper chambers of heart |
| trachea | windpipe |
| respiratory system | transport system that brings oxygen into body |
| bronchial tubes | two tubes that lead to lungs |
| lungs | two spongy, baglike organs in chest |
| diaphragm | sheet of muscle below lungs used in breathing |
