Across
- 5. The release of energy from food
- 7. The air sacs in the lungs
- 8. The top part of the heart
- 9. The lower part of the heart
Down
- 1. The organ that pumps blood around the body
- 2. The tiny blood vessels
- 3. The main organ in the respiratory system
- 4. The small branches in the lungs
- 6. The gas used to create energy
- 8. The artery going from the heart