science

12345678910111213
Across
  1. 1. middle of the heart
  2. 5. voice box
  3. 6. gates in the heart to allow blood flow
  4. 7. small blood vessels that carry oxygen
  5. 10. air rushes in because pressure in chest is low
  6. 12. bones protecting the lungs
Down
  1. 2. the oesophagus of the lungs
  2. 3. main artery
  3. 4. air rushes out because of increase of pressure
  4. 8. blood vessels that lead away from the heart
  5. 9. the organs for breathing
  6. 11. small sacs covered in capillaries
  7. 13. branches that come off the trachea