This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System Pa 1, Subject name: Physiology
In the work of breathing, tissue resistance contributes ___% fraction: 
Select and explain. 
A. 7%, B. 14%, C. 28%, D. 65%
A: 7%
Answer: A: 7% 
Explanation: Work done = load x displacement. In the context of lungs, load is analogous to pressure and displacement is volume expansion of lungs. Hence, work of breathing = DP X DV. Thus, work done can be calculated as area covered under the inspiratory curve in compliance diagram. Of the total inspiratory work, 65% work is elastic work or compliance work. Remaining 35% is non-elastic work - (28% is airway resistance work, 7% is tissue resistance work.)