Circulatory system

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Across
  1. 2. Blood that is low in oxygen.
  2. 5. Blood rich in oxygen.
  3. 7. The expansion of an artery as blood is pumped.
  4. 10. Activity that strengthens the heart.
  5. 13. Cell fragments that help the blood to clot.
  6. 15. Main vein returning deoxygenated blood to the heart.
  7. 16. Upper chamber of the heart that receives blood.
  8. 18. Proteins that fight infection.
  9. 20. Chemical in cigarettes that damages arteries.
  10. 21. Relates to the lungs.
Down
  1. 1. Prevents blood from flowing backwards.
  2. 3. The largest artery in the body.
  3. 4. Vessel with valves that carries blood back to the heart.
  4. 6. Vessel with thick walls that carries blood away from heart.
  5. 7. The liquid part of blood that transports nutrients.
  6. 8. The protein in red blood cells that carries oxygen.
  7. 9. The main job of the circulatory system.
  8. 11. Tiny vessel where gas exchange takes place.
  9. 12. The red fluid that circulates in the body.
  10. 14. The sound made by the valves closing.
  11. 17. Lower chamber that pumps blood out of the heart.
  12. 19. The wall separating the left and right sides of heart.