Respiratory system

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Across
  1. 2. When the lung cavity expands, it ___ers the pressure, making oxygen go inside
  2. 4. There is a high concentration of ______ in the alveoli
  3. 8. Where cells use oxygen to make energy for cells to function. CO2 is a by-product
  4. 9. A Dense network of ______ around the alveoli
  5. 12. Both the alveoli and the bronchioles have a high surface area to _______ ratio
Down
  1. 1. Diffusion is the movement of particles along a _______ gradient
  2. 3. There is a low concentration of _____ in the alveoli
  3. 5. C shaped cartilage
  4. 6. Where Oxygen is diffused into the capillaries and CO2 is diffused into the alveoli. Gas __________.
  5. 7. Our __________ contracts and moves downwards when we breathe
  6. 10. Site of gas exchange, grape like sacs with lots of surface area
  7. 11. When the lung cavity gets smaller, the pressure _________, making oxygen leave the lungs.