Handling of Bioactive Materials by the Lung

Abstract

THE primitive lung was little more than an air sac containing minute vessels in its walls for gas exchange. It served as an accessory organ of breathing that allowed fishes seeking refuge from oxygen-poor waters to survive on land as air breathers.^{1 , 2} In the course of time, as the original fishes out of water were succeeded by generations of vertebrates that were at home on land, the lung grew more complicated. Not only did anatomic arrangements for gas exchange grow more intricate, but additional specializations — some of which were only indirectly related to gas exchange — became evident. Among . . .