Across
- 4. place where substances are exchanged between the blood and body cells
- 7. a flap of tissue that prevents blood from flowing backward
- 8. take up oxygen in the blood and deliver it to cells elsewhere in the body
- 9. the body's defense fighters
- 10. blood vessels that carry blood away from the heart
- 12. iron-containing protein that binds chemically to oxygen molecules
Down
- 1. largest artery in the body
- 2. (singular) lower chambers of the heart
- 3. the liquid part of blood
- 4. consists of the heart, blood vessels,and blood
- 5. a force exerted by blood against the walls of blood vessels
- 6. blood vessels that carry blood back to the heart
- 11. upper chambers of the heart
- 12. hollow, muscular organ that pumps blood throughout the body