Cardiovascular System

2. Gas that enters the blood through the lungs and travels to the heart to be pumped via arteries to all body cells
4. Largest artery in the body.
6. Thin-walled vessel that carries blood from body tissues and lungs back to the heart. Veins contain valves to prevent backﬂow of blood.
7. Beat of the heart as felt through the walls of the arteries.
8. 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.”
11. Record of the electrical activity of the heart. The electricity is represented by waves or deﬂections called P, QRS, or T.
14. Muscular middle layer of the heart.
15. Inner lining of the heart.

1. Innermost lining of blood vessels.
3. Structure in veins or in the heart that temporarily closes an opening so that blood ﬂows in only one direction.
5. Relaxation phase of the heartbeat. (From Greek diastole, dilation)
9. Double-layered membrane surrounding the heart.
10. Abnormal swishing sound caused by improper closure of the heart valves
12. Smallest type of blood vessel. Materials pass to and from the bloodstream through the thin capillary walls.
13. Small artery.