Respiratory system

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Across
  1. 4. blood contains an iron-containing red pigment called _____
  2. 7. when cellular respiration uses oxygen it is called ____
  3. 9. Gas exchange in the lungs happens in the____
  4. 10. Pair of spongy organs protected by Ribcage
Down
  1. 1. Trachea divides into 2 tubes called ____
  2. 2. prevents the food from entering the windpipe
  3. 3. muscles that help in the movement of the rib cage on inhalation and exhalation.
  4. 5. another word for the windpipe
  5. 6. muscle that supports the lungs
  6. 8. common passage for food and air