Fibrous Network of the Lung and its Change with Age

Abstract

The remarkable elastic behaviour of the lung entails both continuous tissue stress and a cyclic stress produced by the fluctuating difference between intrathoracic and intra-alveolar pressures throughout the entire span of life. In spite of these potentially disruptive forces, lung structure is pre- served by the fibrous connective-tissue proteinscollagen, elastin, and reticulin. These extracellular proteins are characterized by their insolubility, resistance to destruction, and high tensile strength. Collagen and elastin both exhibit elastic behaviour, but great extensibility is a property only of elastin. The most reasonable assumption is that the elastic fibres, therefore, are principally responsible for the elastic behaviour of the lung tissue, but sure proof is lacking.