A STUDY OF RESPIRATION 223 



keep the chest walls flexible and capable of full enlarge- 

 ment, regular exercise should be persisted in throughout 

 life. 



Effect of Tight Clothing upon Respiration. In an earlier 

 part of this chapter we learned that air is pumped into the 

 lungs when the ventral ends of the ribs are elevated and the 

 diaphragm is pulled downward toward the horizontal posi- 

 tion. By no other means are ths respiratory organs filled 

 with air, and any interference with the action of either ribs 

 or diaphragm tends to decrease the supply of oxygen and 

 the excretion of carbon dioxid. Tight clothing about the 

 chest and abdomen not only results in permanent distortion 

 of the skeleton (see Fig. 79), but also it retards the move- 

 ments by which the chest cavity is enlarged. Shortness of 

 breath and inability to perform any great amount of muscular 

 exercise are some of the ill effects that are experienced from 

 tight lacing. Diseased conditions of the organs, too, may be 

 brought about when they are thus compressed and forced 

 out of position. It is especially important that loose cloth- 

 ing be worn in the gymnasium, or during any vigorous 

 exercise, in order that the muscles used in motion and respir- 

 ation may be free to work unhampered. 



Diseases of the Respiratory Organs. Colds, we have found, 

 are inflammations of the air passages or of other regions of 

 the body. If the malady is confined to the nose cavity, we 

 call it a head cold ; if it is seated in the pharynx, a sore 

 throat results. A cold on the chest is an inflammation of 

 the windpipe or bronchi. If the bronchial tubes are affected, 

 their lining membrane becomes swollen, a considerable 

 amount of mucus is often secreted, and the air passages are 

 more or less closed ; this is bron-chi'tis. And finally, if the 

 inflammation affects the air sacs, pneu-mo'ni-a is caused. 



Diph-the'ri-a and membranous croup are germ diseases pro- 

 duced by colonies of bacteria that grow in the throat. In 

 the progress of these diseases certain poisons called tox'ins 

 are formed by the growing bacteria, poisons which are ab- 



