The first is intrinsic lung diseases or diseases of the lung parenchyma. The diseases cause inflammation or scarring of the lung tissue (interstitial lung disease) or result in filling of the air spaces with exudate and debris (pneumonitis). These diseases can be characterized according to etiological factors.estrictive lung diseases are characterized by a reduction in FRC and other lung volumes because of pathology in lungs, pleura, or the structures of the thoracic cage. The distensibility of the respiratory system is called compliance, the volume change produced by a change in the distending pressure.