cardio

3. Largest vein in the body. The superior and inferior venae cavae return blood to the right atrium of the heart.
4. Thin-walled vessel that carries blood from body tissues and lungs back to the heart. Veins contain valves to prevent backﬂow of blood.
5. Beat of the heart as felt through the walls of the arteries.
8. Small vein
12. Inner lining of the heart.
13. Gas that enters the blood through the lungs and travels to the heart to be pumped via arteries to all body cells
15. Largest artery in the body
16. Record of the electrical activity of the heart. The electricity is represented by waves or deﬂ ections called P, QRS, or T.
19. Muscular middle layer of the heart.

1. Located between the right atrium and the right ventricle; it has three (tri-) leaﬂets, or cusps.
2. Structure in veins or in the heart that temporarily closes an opening so that blood ﬂows in only one direction.
6. Contraction phase of the heartbeat. (From Greek systole, contraction.)
7. One of two lower chambers of the heart
9. Abnormal swishing sound caused by improper closure of the heart valves
10. Double-layered membrane surrounding the heart.
11. Small artery
14. Largest type of blood vessel; carries blood away from the heart to all parts of the body. Notice that artery and away begin with an “a.”
17. Smallest type of blood vessel. Materials pass to and from the bloodstream through the thin capillary walls.
18. Lower tip of the heart