Circulatory System

3. tiny blood vessel where substances are exchanged between the blood and the body cells
5. group of cells located in the right atrium that sends out signals that make the heart muscle contract and that regulates heartbeat race
6. blood cell that fights disease
10. liquid part of the blood
11. body system that consists of the heart,blood vessels, and blood
15. lower chamber of the heart that pumps blood out to the lungs and body
17. pressure that is exerted by the blood against the walls of blood vessels
19. iron-containing protein that binds chemically to oxygen molecules

1. largest artery in the body
2. flap of tissue in the heart or a vein that prevents blood from flowing backward
4. network of veinlike vessels that returns fluid that leaks out of blood vessels to bloodstream
7. pumps blood throughout the body
8. cell fragment that plays in important part in forming blood clots
9. alternating expansion and relaxation of an artery wall as blood travels through an artery
11. artery that supplies blood to the heart itself
12. blood vessel that carries blood back to the heart
13. blood vessel that carries blood away from the heart
14. each of the two upper chambers of the heart that receives blood tat comes into the heart
16. cell in the blood that takes up oxygen in the lungs and delivers it to cells elsewhere in the body
18. process by which molecules move from an area of higher concentration to an area of lower concentration