1 74 Life and Health 



262. Modified Respiratory Movements. Certain modi- 

 fied respiratory movements need explanation. 



Coughing is usually produced by irritation in the upper part 

 of the windpipe and larynx. A deep breath is drawn, the 

 opening of the windpipe is closed and immediately is burst 

 open with a violent effort, which sends a blast of air through 

 the upper air passages. The object is to expel any mucus 

 or foreign matter that is irritating the air passages. 



Sneezing is like coughing ; the tongue is raised against the 

 soft palate, so that the air is forced through the nasal pas- 

 sages. It is caused by an irritation of the nostrils or eyes. 



Sighing is a rapid and generally audible expiration, due 

 to the elastic recoil of the lungs and chest walls. It is 

 often caused by depressing emotions. Yawning is a deep 

 inspiration with a stretching of the muscles of the face. 

 It is usually excited by fatigue or drowsiness. 



Laughing consists of a series of short, rapid, spasmodic 

 expirations, which cause the peculiar sounds, with char- 

 acteristic movements of the facial muscles. Crying, caused 

 by emotional states, consists of sudden jerky expirations, 

 with long inspirations, and facial movements indicative 

 of distress. In sobbing, which often follows long-continued 

 crying, there is a rapid series of convulsive inspirations, 

 with sudden involuntary contractions of the diaphragm. 



Hiccough is a sudden jerking inspiration due to the spas- 

 modic contraction of the diaphragm and of the vocal cords, 

 causing the air to rush suddenly through the larynx and 

 produce this peculiar sound. 



X 263. How the Atmosphere is made Impure. The air 

 around us is constantly being made impure in a great 

 variety of ways. The combustion of fuel, the respiration 

 of men and animals, the exhalations from their bodies, the 

 noxious gases and effluvia of the various industries, together 



