Cardiovascular system

4. Largest artery in the body.
7. One of two upper chambers of the heart.
11. Record of the electrical activity of the heart. The electricity is represented by waves or deﬂ ections called P, QRS, or T.
12. Small vein.
14. Smallest type of blood vessel. Materials pass to and from the bloodstream through the thin capillary walls.
15. blood Blood that is oxygen-poor.

1. Structure in veins or in the heart that temporarily closes an opening so that blood ﬂows in only one direction.
2. Relaxation phase of the heartbeat. (From Greek diastole, dilation)
3. Contraction phase of the heartbeat. (From Greek systole, contraction.)
5. Gas that enters the blood through the lungs and travels to the heart to be pumped via arteries to all body cells
6. Small artery.
8. Abnormal swishing sound caused by improper closure of the heart valves
9. Beat of the heart as felt through the walls of the arteries.
10. Partition or wall dividing a cavity; such as between the right and left atria (interatrial septum) and right and left ventricles (interventricular septum).
13. Thin-walled vessel that carries blood from body tissues and lungs back to the heart. Veins contain valves to prevent backﬂow of blood.