Gross scheme of a lung lobule and its vascularization (human)

Scheme of branching of intrapulmonary bronchus. A small intrapulmonal bronchus with cartilage rings (1) divides into bronchioli (2), at (3) the terminal bronchioli that continues into respiratory bronchioli (4) followed by alveolar ducts (5) and at (6) the alveoli. A respiratory bronchiolus with alveolar ducts/alveoli forms a small lobular unit, the so-called lung acinus (4+5+6). A lung lobulus comprises of about 200-300 acini. The black pulmonary artery (7) branches into the capillary system of the alveoli. The bronchial arterial system (9) is mainly restricted to the bronchial and bronchiolar branches. The solitary pulmonary veins (8) draining the capillary system of the alveoli are located within the intersegmental septa (10). At (11) superficial lymphatic plexus within the visceral pleura and (12) indicates the deep pulmonary lymphatic plexus.