Across
- 3. Blood vessels that carry blood back to the heart
- 5. Hollow, muscular organ that pumps blood throughout the body
- 10. Consists of the heart, blood vessels, and blood
- 12. The largest artery in the body
- 13. The alternating expansion and relaxation of the artery walls
- 15. Iron-containing protein that binds chemically to oxygen molecules
- 16. Either lower chamber of the heart
Down
- 1. a flap of tissue that prevents blood from flowing backward
- 2. smallest level of blood vessel
- 4. location where oxygen enters the blood
- 6. Either upper chamber of the heart
- 7. The process by which particles move from an area of high concentration to an area of lower concentration
- 8. These fight disease and infection
- 9. The liquid part of the blood
- 11. Blood vessels that carry blood away from the heart
- 14. play an important role in forming blood clots