On the Changes of the Lumen of the Bronchi During Respiration and Cough

Abstract

It is not generally known that the changing of the lumen of the bronchi in respiration and coughing depends on two factors: (1) the changes of the volume of the lung and (2) the pressure differences of the air inside and outside the bronchi. They can also be distinguished in (1) the static and (2) the dynamic factor. Both factors produce a widening of the bronchi in inspiration and a narrowing in expiration. But there is also a difference. The static factor acts more on the smaller bronchi and the dynamic factor acts more on the larger bronchi. This is very pronounced in a cough. There is still much difference of opinion about what is happening in a cough. The conceptions of Stutz are confirmed, the narrowing of the large bronchi in a cough is of physiological importance.