Heart and Circulatory system

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Across
  1. 4. Related to the lungs
  2. 8. Blood carrying oxygen
  3. 10. Lower chambers of the heart
  4. 11. Upper chamber of the heart
  5. 12. The biggest artery that pumps blood to the rest of the body
  6. 13. Inside structure of blood vessel
Down
  1. 1. Thin-walled blood vessel
  2. 2. The type of circulatory system humans have
  3. 3. Property of arteries
  4. 5. Blood with not much / no oxygen
  5. 6. Structure that prevents backflow
  6. 7. Carries blood to the heart
  7. 9. Blood vessel that carries blood away from the heart