RESPIRATION 



the small hairs in the nose, but mainly through the moist 



membrane that lines the passages, the nostrils serve as 



niters for removing the minute solid particles (Fig. 45). 



While it is important that 



nose breathing be observed 



at all times, it is especially 



important when one is sur- 



rounded by a dusty or smoky 



atmosphere. Otherwise the 



small particles that are 



breathed in through the 



mouth may find a lodging 



place in the lungs. 



In addition to removing 

 dust particles and germs, 

 other purposes are served 



FK, 45. - Human air filter. Di- 



agram of a section through the nos- 



trils . shows projecting bones covered 



nostrils. The warmth and with moist membrane against which 

 moisture which the air re- the air is made to strike by the narrow 



uu ' Air P assa e es - ^. Cavities 



in the bones. 3. Front lower portion 



, . 



by breathing through the 



ceives in this way, prepare assages - 



, 



it for entering the lungs. of the cranial cavity. 



Mouth breathing, on the 



other hand, looks bad and during sleep causes snoring. 



The habit of nose breathing should be established early 



in life. 1 



Cultivate Full Breathing. Many people, while appar- 

 ently taking in sufficient air to supply their need for 

 oxygen, do not breathe deeply enough to " freely venti- 

 late the lungs." " Shallow breathing," as this is called, 



1 Some children find it difficult to breathe through the nostrils on account of 

 growths (called adenoids) in the upper pharynx. Such children should have 

 medical attention. The removal of these growths not only improves the method of 

 breathing, but in many instances causes a marked improvement in the general 

 health and personal appearance. 



