The architecture of the lung is discussed with special focus on lung
parenchyma. The lung parenchyma is mainly comprised of numerous
air-containing passages and intervening fine structures, corresponding
to alveolar ductal lumens and alveoli, as well as alveolar septa and
small pulmonary vessels occupying 10\% of total parenchymal volume. The
shapes and relative arrangements of alveolar ducts and alveoli are
discussed in detail, which is followed by a brief description of
bronchial circulation and pulmonary lymphatics.