Heart and circulation

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Across
  1. 1. ensure that blood travels in one direction only
  2. 4. a gas carried by red blood cells
  3. 6. the bottom chambers of the heart
  4. 8. the largest artery in the body
  5. 10. liquid carried in the circulatory system
  6. 11. the number of chambers in the heart
  7. 12. carry oxygen in the blood
  8. 15. these vessels carry blood away from the heart
  9. 16. another name for cardiac arrest
  10. 17. these blood vessels carry blood into the heart
Down
  1. 2. this bad habit can lead to heart disease
  2. 3. the job of the heart
  3. 5. blood with very little oxygen in it
  4. 7. the smallest blood vessels
  5. 9. carries blood away from the heart to the lungs
  6. 13. the main vein of the body
  7. 14. the side of the heart with a thicker muscle wall