Across
- 2. where the great vessels enter and leave the heart
- 5. ventricular contraction
- 7. two upper chambers of the heart
- 10. ability to contract without stimulation
- 12. thin layer covering the heart surface
- 13. period of cardiac muscle relaxation
Down
- 1. space where the heart resides
- 3. double-walled sac surrounding the heart
- 4. two lower chambers of the heart
- 6. the heart's inner layer
- 8. the study of the heart
- 9. heart's middle layer
- 11. pointed end of the heart