hans puzzle

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Across
  1. 2. How many muscles are in a hand
  2. 3. what is the main part of the nervous system
  3. 6. what is the hardest bone in the body
  4. 10. small flap of tissue that covers the wind pipe
  5. 13. what is another name for the voice box
  6. 15. what muscles hold the skeleton together
  7. 17. vessels that carry blood away from the heart
  8. 18. how many chambers does the heart have
  9. 19. what you breathe in when you inhale
  10. 20. what carries the blood to the heart
Down
  1. 1. the part of the brain that controls appetite
  2. 4. what type of bone tissue resembles a sponge
  3. 5. the exchange of oxygen and carbon dioxide
  4. 7. the muscles that surround the femur bone
  5. 8. What is the thickest layer of the heart wall
  6. 9. what is the smallest bone in the body
  7. 11. what framework of protein are bones made of
  8. 12. the cells that make of the nervous system
  9. 14. what system is acting when you feel pain
  10. 16. largest blood vessel in the entire body