| FIG. 975– Schematic longitudinal section of a primary lobule of the lung (anatomical unit); r. b., respiratory bronchiole; al. d., alveolar duct; at., atria; a. s., alveolar sac; a, alveolus or air cell; p. a.: pulmonary artery: p. v., pulmonary vein; l., lymphatic; l. n., lymph node. (Miller.) |
