332 EESFIKATION 



short expirations followed by a long inspiration. Hiccoughs are 

 caused by a sudden contraction of the diaphragm. Yawning is a 

 long inspiration and expiration through the open mouth while the 

 throat muscles are held rigid. Sighing is similar, except that the 

 inspiration is through the nose, and the muscles are suddenly 

 relaxed after the inspiration, thus making a sound. Snoring is 

 produced by the inspired air passing over the soft palate and 

 setting up a vibration. Spitting is a use of expired air to force 

 matter from the mouth. It may be done by the action of the 

 mouth muscles alone. 



In general, then, all these modifications of respiratory move- 

 ments are essentially reflex, that is, they take place without any 

 act or will on our part, and often in spite of our desire to the con- 

 trary. Spitting is an exception to this rule, though that may 

 become a habit. Most of them, with the exception of hiccoughs, 

 are under our control to a certain extent. 



Asphyxiation and artificial respiration. — Asphjrxiation is death 

 from suffocation or the lack of oxygen supply. It may be brought 

 about in various ways. Blocking the tracheal entrance by pres- 

 sure applied to the outside of the throat, as in strangulation, is 

 one method. Exposure in a medium containing no oxygen is 

 another. Exposure to gases which have a greater affinity for the 

 haemoglobin of the blood than oxygen, and hence turn it out of 

 the corpuscles, produces the same result. Carbon monoxide or 

 the gas produced in burning charcoal is an example of such a 

 cause. In general, any cause that deprives the lungs of their 

 normal supply of oxygen will eventually produce asphyxiation. 



When the tissues find their oxygen supply reduced in any of 

 the above ways, the first visible symptom of this lack is seen in 

 the deeper and more rapid breathing. Then the breathing loses 

 its regularity, and soon convulsions follow. Gradually these con- 

 vulsions spread until other muscles beside those concerned in 

 breathing are affected, and the whole body is thrown into violent 

 spasms. Finally the muscles become exhausted, the movements 

 decrease and finally cease altogether, consciousness goes and the 

 animal is soon still in death unless remedies of a powerful char- 

 acter are soon applied. What these remedies shall be is largely 

 determined by the cause of the asphyxiation, and resource should 



