Cardiovascular System Crossword

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Across
  1. 3. | Muscular organ that pumps blood throughout the body
  2. 5. | Smallest blood vessel; where exchange of gases occurs
  3. 8. | Lower chamber of the heart (singular)
  4. 9. | The muscular middle layer of the heart wall
Down
  1. 1. | Vessel that returns blood to the heart
  2. 2. | Vessel that carries blood away from the heart
  3. 4. | Prevents backflow of blood in the heart or veins
  4. 6. | Upper chamber of the heart (singular)
  5. 7. | The protective sac surrounding the heart
  6. 10. | The largest artery in the body