Ek. Verbeken et al., MEMBRANOUS BRONCHIOLES AND CONNECTIVE-TISSUE NETWORK OF NORMAL AND EMPHYSEMATOUS LUNGS, Journal of applied physiology, 81(6), 1996, pp. 2468-2480
Three-dimensional reconstructions of the septal system of normal human
lungs revealed that airways course within the interlobular septa, i.e
., between the two blades formed by the peripheral boundaries of adjac
ent lobuli of whatever order, and enter the supplied pulmonary unit at
its side. This is not in keeping with the classic view of a periphera
l airway in the center of a lung unit and submitted to radial traction
by attached alveolar septa. The basic design of the lung fibrous scaf
fold appears to be in conformity with the laws of fractal geometry. Si
milar reconstructions in centrilobular emphysema disclosed tortuositie
s of both intra-acinar and interlobular septa, with consequent distort
ions of the corresponding intraseptal bronchioles and collapse of lung
units of different sizes. It is suggested that in centrilobular emphy
sema competition for space, besides intrinsic airways narrowing becaus
e of inflammation and loss of elastic recoil, is a cause of flow limit
ation.