1 64 



OUR BODIES AND HOW WE LIVE 



growing upside down in the chest, of which the windpipe 



is the trunk, the bronchial tubes are the branches, and the 



air cavities of the lungs are the leaves. 



224. The Lungs. The lungs are two large, pinkish, 



spongy organs, which surround the heart and the large 



vessels, and fill up 

 all the rest of the 

 chest cavity. So 

 light and spongy is 

 their structure that 

 a piece of a lung, 

 unlike any other 

 tissue, will float in 

 water. 



The right lung 

 is the larger of the 

 two, and has three 

 parts, or lobes. The 



FIG. 102. The Lungs, with the Trachea, Bronchi, left lun & haS 



and Larger Bronchial Tubes exposed. (Pos- two lobes. Each 



*' looe is also made 



A, division of left bronchus to upper lobe ; B, left branch 



of the pulmonary artery; C, left bronchus; D, left U P f man Y g rou PS 



superior pulmonary vein ; E, left inferior pulmonary of Smaller part S, 



vein; P, left auricle ; K, inferior vena cava ; L, divis- 11 1 i K 1 V> 



ion of right bronchus to lower lobe ; M, right inferior Cal1 1 loDules > eac 



pulmonary vein ; N, right superior pulmonary vein; with its little bron- 



O, right branch of the pulmonary artery ; P, division , -, -, 



of right bronchus to upper lobe; R, left ventricle; cniai tUDC, air SaCS, 



S, right ventricle. and blood VCSSels. 



The chest is lined and each lung covered with a smooth, 

 delicate lining, called the pleura. These two surfaces rub 

 against each other when we breathe. This lining secretes 

 a fluid which keeps the parts always moist and prevents 

 their rubbing on one another. 



