Across
- 5. flat discs that don't contain nuclei
- 8. exchange of substances that occurs between the blood in the capillaries
- 10. white blood cells
- 11. the two upper chambers
- 12. carry blood towards the heart.
Down
- 1. Thick walls to pump blood out of the heart
- 2. red blood cells
- 3. thin membrane that lines the inside of the heart
- 4. tool used to heartbeats
- 6. sticky, dark red fluid with a salty flavour
- 7. transporting nutrients to their target organs
- 9. carry blood away from the heart