126 



RESPIRATION 



ear or by means of magnifying instruments, such as the stethoscope or 

 phonendoscope. Accompanying normal breathing through average 

 respiratory organs is a set of sounds called by the diagnostician "nor- 

 mal." When either the function or the organs are materially altered the 

 sounds also are changed and thus become valuable means of diagnos- 

 ticating and locating disease. This is the important art of auscultation. 



Two sounds made in normal breathing bronchial breathing and 

 vesicular murmur are especially important. 



Bronchial breathing is the sound natural to the passage of a current 

 of air over imperfectly vibrating strings within a tube. It is caused by the 

 rapid movement of the air passing through the glottis. It is heard during 

 both inspiration and expiration, and best over the larynx and the trachea. 



FIG. 69 



Bronchial. 

 (Tubular element 

 less intense. ) 



Normal 



Cavernous or 

 amphoric. 



Pure bronchial- 



Broncho-Vesicular. I I 



(Conduction of bronchial / | 



element by increased I k 



interstitial tissue.) I L 



Exaggerated. 

 (Compensatory 

 emphysema.) 



Feeble or absent. 

 (Actelectasis due 

 to plugging of 

 \ bronchi.) 



\Broncho -Vesicular. 



Diagram of the modification of breath-sounds as heard on auscultation. (Le Fevre.) 



It can also be distinguished below the trachea, but not unmixed with 

 sound produced in the lung-tissue proper. Between the scapulae, behind, 

 it is somewhat less distinct than over the trachea. The pitch of bronchial 

 respiration is high, that of expiration being somewhat higher than that 

 of inspiration. The intensity is about equal in the two phases, as is also 

 the duration. 



The vesicular murmur is so called because it is largely caused by the 

 expansion and recoil of the air- vesicles or alveoli, complicated, however, 

 with the tubular sounds produced in the bronchioles. The murmur of 

 the inspiratory phase is about four times as long in duration as that of 

 expiration, gradually increasing to a maximum and decreasing again 

 by degrees. A slight pause intervenes between the sounds of the two 

 phases. In quiet breathing the expiratory murmur may be difficult to 



