Across
- 1. One of two lower chambers of the heart.
- 3. in only one direction.
- 4. Small vein.
- 6. small artery.
- 10. Muscular middle layer of the heart.
- 13. closes an opening so that blood
- 14. Double-layered membrane surrounding the
- 15. of the arteries.
- 17. Largest type of blood vessel.
Down
- 2. Innermost lining of blood vessels.
- 5. Inner lining of the heart.
- 7. Largest artery in the body.
- 8. Beat of the heart as felt through the
- 9. Contraction phase of the heartbeat.
- 11. One of two upper chambers of the heart.
- 12. Smallest type of blood vessel.
- 16. Structure in veins or in the heart that