1							2												3					4
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13
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15														16				17
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27

Across 6. Get larger as they approach the heart 9. Route by which oxygenated blood returns to the heart 11. Capillaries drain into these small vessels 13. Empties into the top portion of the right atrium 15. Number of chambers in the heart 18. Room air is 21% this 21. Separates the right ventricle from the pulmonary artery 23. Smallest arteries in the body 25. Separates the left ventricle from the aorta 26. Has two leaves or flaps 27. Separates the right atrium from the right ventricle

Down 1. Get smaller as they get farther away from the heart 2. Pulmonary veins empty into this 3. Nature of blood as it returns to the heart from the lungs 4. Smallest veins in the body 5. Powerhouse of the heart...strongest of all chambers 7. Vessel by which deoxygenated blood leaves the heart 8. Nature of blood as it returns to the heart from the body 10. Empties into the lower portion of the right atrium 12. First chamber of the heart 14. Vessels that empty into the capillary bed 16. Tricuspid valve opens into this 17. Number of valves in the heart 19. Waste product of metabolism 20. Place at which gas exchange occurs 22. Largest artery in the body 24. Organs that take in oxygen and give off carbon dioxide