Excuse me, can I add one more question? 
In a patient with obstructive disease, let's say asthmatic patient, the airway diameter is smaller, so how is he going to breath in the same amout of air. Is it a matter of time? 
I mean, he would breath the same amount of air as a normal person, but in more time? (with decreased slope factore  in a volume-time diagram for instance ? )

Dear Dr. Mobeen,
I would like to ask 2 questions. 

1) In a patient with emphysema, there  are dilated alvioli and "trapped air". So there is increased residual volume. So far so good, BUT, since the alvioli membranes are destroyed and on top of that there is trapped air, shouldn't that mean that the alvioli of the damadged area are less compliant and thus they can take in less air. ? So why is there a normal inspiration volume? I understand the normal FVC only because of an increased RV. But is the IV normal? Can the patient with emphysema inspire the same amount of air as with a normal person? 

2)  In the restrictive diseases, you mentioned that the scar is pulling airways open, (I understand it as pulling the airways out and they open ). Compliance is less. So IV is less.  But since the scar is pulling outwards, why do they tend to collapse?, why is the recoil force intact ? (since there is a force pulling in the opposite direction of that of collapsing ) and by extention why is the expiration process normal?

Thank you very much doctor. You are really making us better professionals. Can't thank you enough for all of your lectures (And this is a genuine expression of appreciation)