Cardiac 101

2. Blood vessels that deliver oxygen-poor blood to the lungs for gas exchange.
5. A heartbeat that is consistently faster than 100 bpm.
6. A heartbeat that is consistently slower than 60 bpm.
9. An abnormal pattern of electrical activity in the heart.
11. The heart’s backup pacemaker when the SA node fails.
12. The electrical process when heart muscle resets after contraction.
13. The major vessel that carries blood out of the left ventricle.
16. Lower chamber that sends oxygenated blood into the main artery.
18. The sac that reduces friction as the heart beats inside the chest.
19. Blood vessels that carry oxygenated blood to the heart’s left atrium.
20. Muscle layer thicker on the left side because it pumps to the whole body.
21. Large vein returning blood from below the diaphragm.

1. The inner heart lining where blood flows with minimal resistance.
3. The layer of the heart that contracts with every heartbeat.
4. Upper chamber that collects oxygen‑poor blood returning from the body.
7. The electrical process when heart muscle cells become more positively charged.
8. Valve that prevents backflow from the aorta into the left ventricle.
10. Artery that carries blood from the right ventricle to the lungs.
14. Large vein returning blood from the upper body to the heart.
15. Valve that opens when blood moves from the right atrium to the right ventricle.
17. A conduction degree block where the PR interval is longer than normal.