Across
- 2. gas that enters blood through lungs and travels to the heart
- 3. faster than 60 beats per minute
- 6. one of two upper chambers of the heart
- 8. small vein
- 10. instrument to measure blood pressure
- 13. relaxation phase of the heartbeat
- 15. double-layered membrane surrounding the heart
Down
- 1. muscular middle layer of the heart
- 4. largest artery in the body
- 5. blood blood that is oxygen-poor
- 7. contraction phase of the heartbeat
- 9. innermost lining of the heart
- 11. valve located between the right atrium and the right ventricle
- 12. smallest type of blood vessel
- 14. cava largest vein in the body