THE NOSE. ' 353 



tissues. This condition exists in man, many of whose tissues are 

 so deeply situated that without such provision the maintenance 

 of life would be impossible. In man this medium is the blood. 

 But additional provision must be made for the renewal of the 

 oxygen abstracted by the tissues. That part of the process by 

 which the tissues take oxygen from the blood is internal respiration, 

 and that part by which the renewal is accomplished is external 

 respiration. Ordinarily, when respiration is spoken of without 

 qualification it is external respiration that is referred to. 



Respiratory Apparatus. The group of organs concerned 

 in external respiration is collectively spoken of as the respiratory 

 apparatus, which consists of the nose, larynx, trachea, bronchi, 

 lungs, and thorax. 



THE NOSE. 



The nose is the beginning of the air-passages, for although it 

 is regarded by many as the organ of smell only, it has another 

 function as well. The mouth belongs to the alimentary canal, and 

 should be opened only to take in food or to speak, never to take 

 in air. The proper channel for the admission of air is the nose, 

 and the use of the mouth for this purpose is not physiologic. 

 Indeed, man is said to be the only animal that breathes through 

 the mouth. If the nursing child should attempt to use its mouth 

 for the admission of air to the lungs, sucking could not be performed 

 without great difficulty, and after a few moments the child would 

 be compelled to let go the breast in order not to suffocate. 



Mouth-breathing". There is no more pernicious habit, so 

 far as health is concerned, than breathing through the mouth. If 

 this is due to habit and to nothing else, it may be overcome ; but 

 if, as is often the case, it is due to some diseased condition of the 

 nose, or to the presence in the nasal cavities of tumors, or to the 

 existence of enlarged tonsils, its relief can be accomplished only 

 by surgical means. The function of the nose in respiration is to 

 warm the air and to filter out from it dust and other extraneous 

 matter which would otherwise enter the air-passages and cause 

 irritation. When air is taken in by the mouth these beneficial 

 results do not occur. 



Mouth-breathing causes dryness of the mouth and the pharynx, 

 which condition is very noticeable on awaking from sleep. The 

 mucous membrane becomes congested and inflammation is likely 

 to follow. A chronic inflammatory condition of the larynx may 

 also result from this cause, and the evidence is very conclusive 

 that the hearing becomes affected in these cases. The deformity 

 known as pigeon-breast is not an uncommon sequel. Indeed, the 

 consequences of mouth -breathing are numerous, widespread, and 

 serious, and the subject has never received the attention which its 

 importance demands. 



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