AS Biology new specification 7401/7402Watch
About the diseases of the lung you don't need to know the specific names of the disease and the complications it makes. You just need to know the effect of these diseases on respiration.
So in an exam question it will tell you that a certain person has such a disease and the complication it has made to the lung. It may ask you what effect does this have on the tidal volume. If the short diffusion pathway is affected by the disease then you would say that there is no longer a short diffusion pathway therefore making the tidal volume decrease.