Human Systems Crossword Puzzle

1234567
Across
  1. 4. main organ of nervous system
  2. 6. main organ of digestive system
  3. 7. main organ of integumentary system
Down
  1. 1. main organ of the cardiovascular system
  2. 2. main organ of the respiratory system
  3. 3. main organs of the muscular system
  4. 5. strongest bone in the skeletal system