Cardiovascular

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Across
  1. 5. small artery
  2. 8. small vein
  3. 11. Muscular middle layer of the heart
  4. 12. blue
  5. 13. upper chambers of the heart
Down
  1. 1. a lipid substance
  2. 2. Double-layered membrane surrounding the heart
  3. 3. Contraction phase of the heartbeat
  4. 4. Relaxation phase of the heartbeat
  5. 6. relating to the arteries which surround and supply the heart
  6. 7. Smallest type of blood vessel
  7. 8. lower chambers of the heart
  8. 9. Inner lining of the heart
  9. 10. Double-layered membrane surrounding the heart
  10. 13. largest artery in the body