THE LUNGS. 



173 



f Bronchus, etc. ~} 



From above, downwards, on > / 



4 Pulmonary artery. J- B. A. V. 



right side of body. J . 3 ( 



\_ Pulmonary veins, j 



( Pulmonary artery. 

 From above, downwards, on \ 



, rt . , f , , < Bronchus, etc. 



left sid of body. 



^ Pulmonary veins. 



A. B. V. 



Describe the Structure of the Lung. The lung has a serous coat (the 

 pleura) ; a sub-serous, elastic areolar tissue, investing the entire organ, and ex- 

 tending inwards between the lobules ; and the parenchyma, or true lung-tissue, 



FIG. 85. 



composed of 



Lobules, each consisting of several air- 

 cells or compartments, arranged around 

 the termination of a bronchiole, and 

 surrounded by 6 plexuses of pulmon- 

 ary and bronchial arteries and veins, 

 lymphatics and nerves. Each lobule 

 is a miniature lung, pyramidal in form, 

 with base outwards, and about j 1 ^ inch 

 in diameter. 



Alveoli, or Air-cells, are separated from 

 each other by thin septa, are lined 

 with pavement epithelium on a base- 

 ment membrane, and vary in diam- 

 eter from 2^ to -fa inch. [See Fig. 

 85-] 



Name the Vessels and Nerves of the Lungs. The lungs are nour- 

 ished by the bronchial arteries, and supplied with blood for oxygenation by 

 the pulmonary arteries. 



Bronchial Arteries, are derived from the thoracic aorta. 



Pulmonary Arteries, are derived from the right heart. 



Bronchial Veins, open on the right side into the vena azygos, on the left 

 side into the superior intercostal vein. 



Pulmonary Veins, open by 4 large orifices into the left auricle of the 

 heart, carrying oxygenated blood from the lungs to the heart. 



Lymphatics, terminate in the bronchial glands. 



Nerves, are branches from the pneumogastric and the sympathetic, form- 

 ing the Anterior and Posterior Pulmonary Plexuses, from which filaments 

 are distributed to each lobule. 



