Gas exchange in the alveoli

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Across
  1. 3. Thin layer of cells lining the alveoli
  2. 6. Basic unit of life; red ones carry oxygen
  3. 9. Type of fibres in alveoli walls that allow them to stretch and recoil
  4. 10. Movement of molecules from high to low concentration
  5. 13. Protein in red blood cells that binds oxygen
  6. 14. Gas needed by cells for respiration, absorbed in alveoli
  7. 16. Tiny air sacs in the lungs where gas exchange takes place
  8. 17. Organs that contain millions of alveoli
Down
  1. 1. Tiny blood vessels surrounding alveoli for gas diffusion
  2. 2. Steep concentration difference that drives diffusion
  3. 4. Thin barrier through which gases diffuse
  4. 5. Fluid that carries gases, nutrients, and waste
  5. 7. Process where oxygen enters blood and carbon dioxide leaves
  6. 8. Breathing movements that refresh air in the lungs
  7. 11. Color of blood cells that transport oxygen
  8. 12. Structures in alveoli walls that help prevent bursting
  9. 15. Oxygen and carbon dioxide are examples of this