Across
- 3. upper chambers of the heart; receive blood into the heart from the body tissues
- 6. carries oxygen to all the organs in the body
- 8. chemical that humans can not live without; gas that humans breathe in
- 9. a substance in red blood cells that carries oxygen and gives blood its red color
- 11. carry blood away from the heart
- 12. lower chambers of the heart; pump blood to the organs
- 14. the middle layer of the heart
- 16. small veins
Down
- 1. the outer layer of the heart
- 2. needed for blood clotting
- 4. the inner layer of the heart
- 5. pumps blood through the blood vessels
- 7. mostly water; found in blood
- 10. carry blood back to the heart
- 13. fine branching blood vessels, and transport blood, nutrients, and oxygen to the cells
- 15. are between the atria and ventricles