Across
- 5. A group of cells that signals the heart to pump
- 6. A hollow, muscular organ that pumps blood
- 10. A flap of tissue preventing blood from flowing backward
- 11. Tiny vessels where substances are exchanged between blood and cells
- 12. Molecules move from high concentration to low concentration
Down
- 1. The largest artery in the body
- 2. Made up of the heart, blood vessels, and blood
- 3. Receives blood
- 4. Pumps blood out of the heart
- 7. Carries blood away from heart
- 8. Pressure The force with which ventricles contract
- 9. Carries blood back to heart