Across
- 4. blood vessel that carries blood away from the heart
- 6. valve between the left atrium and left ventricle
- 8. lower chamber of the heart
- 10. brief period of rest in the heart
- 11. protect our body against infection
- 12. upper chamber of the heart
Down
- 1. fluid portion of blood
- 2. largest artery
- 3. period of ventricular contraction in the heart (working phase of the heart)
- 5. outside layer of the heart
- 7. complex protein on red blood cells
- 9. blood vessel that carries blood back to the heart