Heart and Lungs

4. The force exerted by circulating blood on the walls of blood vessels (8 letters)
5. Muscle that aids in breathing by contracting and expanding (9 letters)
10. Condition of abnormally high blood pressure (12 letters)
11. The amount of space that a substance (like air or blood) occupies (6 letters)
13. Blood vessels that carry blood back to the heart (5 letters)
15. Smallest blood vessels where exchange of gases occurs (11 letters)
17. What heart muscles do between beats (5 letters)
19. To shorten or tighten, as muscles do during a heartbeat (8 letters)
20. A condition caused by the interruption of blood supply to the brain (6 letters)
21. Valve located between the left atrium and left ventricle (6 letters)
22. Blood vessels that carry blood away from the heart (8 letters)
23. The process of exchanging oxygen and carbon dioxide in the lungs (11 letters)
24. The largest artery in the body (5 letters)
25. Tiny air sacs in the lungs where gas exchange occurs (7 letters)

1. Organs responsible for the exchange of oxygen and carbon dioxide (5 letters)
2. Blood lacking oxygen, usually returning to the heart from the body (13 letters)
3. Organ that controls bodily functions and thought processes (5 letters)
6. Main organ that pumps blood throughout the body (5 letters)
7. Tissue that contracts to produce movement, such as in the heart (6 letters)
8. Gas that is essential for cellular respiration (6 letters)
9. Upper chamber of the heart that receives blood (6 letters)
11. Lower chamber of the heart that pumps blood out (9 letters)
12. The amount of air taken in during each breath (5 letters)
13. Structure that prevents the backflow of blood in the heart (5 letters)
14. Wall that separates the left and right sides of the heart (6 letters)
16. The process of moving air in and out of the lungs (11 letters)
18. Valve located between the right atrium and right ventricle (9 letters)
23. The number of heartbeats per minute (4 letters)