| A | B |
|---|
| Capillary | tiny blood vessels that are one cell layer thick, connect arteries and veins, and only allow one blood cell at a time to pass through |
| valve | a flap that closes to only allow blood flow in one direction |
| heart | an organ made of cardiac tissue designed to pump blood throughout the body |
| Artery | blood vessel that carries blood away from the heart and has a thick layer of elastic connective tissue |
| Vein | blood vessel that carries blood back into the heart and contains valves to ensure blood only travels in one direction |
| Atrium(atria) | the two upper chambers of the heart |
| Ventricles | the two lower chambers of the heart |
| red blood cells | carry oxygen to all of the cells in your body |
| white blood cells | fight infection |
| platelets | clot blood |
| plasma | liquid part of blood made mostly of water and contains nutrients |
