Crossword Key

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Across
  1. 5. ____ Circuit; Carries oxygenated blood
  2. 8. Blood clotting
  3. 9. Tissue barrier that separates the heart in two
  4. 10. Protective layer surrounding the heart
  5. 11. Percentage of red blood cells
  6. 12. Relaxation of the heart muscle
Down
  1. 1. Lower chambers of the heart
  2. 2. ____ Circuit; Carries deoxygenated blood
  3. 3. Thickest layer of the heart
  4. 4. Cells that protect the body from foreign substances
  5. 6. Transports oxygen, waste, and hormones
  6. 7. Upper chambers of the heart
  7. 9. Contraction of the heart muscle
  8. 10. The fluid matrix of blood
  9. 11. Pump of the cardiovascular system