Across
- 5. small artery
- 8. small vein
- 11. Muscular middle layer of the heart
- 12. blue
- 13. upper chambers of the heart
Down
- 1. a lipid substance
- 2. Double-layered membrane surrounding the heart
- 3. Contraction phase of the heartbeat
- 4. Relaxation phase of the heartbeat
- 6. relating to the arteries which surround and supply the heart
- 7. Smallest type of blood vessel
- 8. lower chambers of the heart
- 9. Inner lining of the heart
- 10. Double-layered membrane surrounding the heart
- 13. largest artery in the body