At the centre of the respiratory system are the lungs, where breathed-in oxygen is exchanged for carbon dioxide from the blood.
(At the centre of the respiratory system; are; the lungs, where breathed-in oxygen is exchanged for carbon dioxide from the blood) (breathed-in oxygen; is exchanged; for carbon dioxide; L:the lungs)
At the centre of the respiratory system breathed-in oxygen
are is exchanged
the lungs, where breathed-in oxygen is exchanged for carbon dioxide from the blood
for carbon dioxide L:the lungs