Respiratory System

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Across
  1. 2. the trachea branches into two narrower tubes called _______ that lead into the lungs
  2. 5. the movement of air into and out of the lungs
  3. 9. every cell in the body needs oxygen for a chemical reaction called
  4. 10. the main organs of the respiratory system
Down
  1. 1. below the lungs is a large muscle called the ________ that contracts as you breathe
  2. 3. signals from the ________ system trigger breathing
  3. 4. air moves into a windpipe or _______, a tube that is held open by C-shaped rings of cartilage
  4. 6. the nervous, circulatory and respiratory systems work together to maintain ________
  5. 7. a tube-like passage way at the top of the throat that receives air, food, and liquid from the mouth or nose
  6. 8. the tubes in the lungs end in microscopic sacs called ________