RESPIRATION. 95 



Abdominal and Thoracic Respiration. The main part 

 of respiration is performed by the diaphragm, and the more 

 common mode of respiration is therefore called abdominal 

 or diaphragmatic respiration. In women of the civilized 

 races respiration is more largely accomplished by the action 

 of the thoracic muscles, and is called thoracic or costal res- 

 piration. In children the respiration is of the abdominal 

 type. 



The Rate of Respiration. The rate of respiration in 

 the adult varies from sixteen to twenty-four per minute, 

 the average being about seventeen times a minute ; about 

 one respiration for every four heart beats. Light is favor- 

 able to respiratory activity. The rate is affected by the 

 position of the body, state of activity, temperature, diges- 

 tion, emotions, age, disease, etc. Ordinary inspiration 

 takes slightly less time than expiration. 



Modifications of Respiration. Coughing is a forcible expiration, 

 usually directed through the mouth, and for the purpose of getting rid 

 of some foreign substance, or caused by irritation. In sneezing there is 

 first a deep inspiration, and then the current of air is forced out, chiefly 

 through the nose. Sneezing may be prevented by pressing firmly on 

 the upper lip. Crying, laughing, sobbing, are modifications of respira- 

 tion connected with certain emotions. Yawning and sighing are deeper 

 breathings, caused by etijiui, depressing emotions, or a deficient ventila- 

 tion. Hiccuping is sudden inspiration, produced by spasmodic action 

 of the diaphragm, accompanied by sudden closure of the glottis, and is 

 often caused by some disorder of stomach digestion. Snoring is caused 

 by breathing through the mouth and setting the soft palate into vibra- 

 tion. Sniffing is sudden inspiration : the diaphragm is suddenly pulled 

 down, the air in the nasal cavity is thus drawn downward, and the air 

 we wish to test, or the odor we wish to inhale, is thus drawn into the 

 upper nasal cavities ; whereas in ordinary inspiration most of the air 

 passes along the lower part of the nasal passage. In hawking, the air 

 is forced out through the narrowed passage between the root of the 

 tongue and the soft palate to remove mucus. Gargling is forcing air up 



