Cardiology Puzzle

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Across
  1. 3. smallest blood vessel
  2. 5. inner lining of blood vessels
  3. 6. small artery
  4. 9. muscle layer of heart
  5. 13. pacemaker
  6. 14. small vein
  7. 15. largest blood vessel
Down
  1. 1. lower chamber of the heart
  2. 2. beat of the heart
  3. 4. tissue dividing the heart into chambers
  4. 7. graph of heartbeat
  5. 8. contraction of heart
  6. 10. relaxation of the heart
  7. 11. improper closure of valves causes swishing
  8. 12. largest artery in body