Respiratory (Biology)
Physiology, Acid Buffering: Acid Base Tutorial, University of Connecticut Health Center 
A good explanation on Acid-Base physiological issues. This is more oriented towards physiologists than biochemists but well written either way.
Static Elastic Properties of the Lung and Chest Wall 
This is a pretty nice step by step tutorial on the static elastic properties of the lung and chest wall. They are basically explaining the theory of recoil pressure and how it is measured. There are some quiz questions to help you understand.
