Human Body Systems Crossword

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Across
  1. 3. Tiny air sacs in lungs
  2. 4. System that fights illness
  3. 5. Filters blood
  4. 7. Main organ of the nervous system
  5. 9. Tube for food to stomach
  6. 12. System for breathing
  7. 15. Connects bones together
Down
  1. 1. Basic unit of life
  2. 2. Breaks down food
  3. 6. System that controls the body
  4. 8. Organ that pumps blood
  5. 10. Makes hormones
  6. 11. Red liquid in veins
  7. 13. Organ that controls sugar
  8. 14. Gas you breathe in