THE LUNGS 2O3 



produces an inspiration. Then carry the arms directly 

 forward and down and press them forcibly against the 

 side of the chest. This produces an expiration. These 

 movements should be repeated about fifteen or twenty 

 times a minute, or at the rate of natural breathing. 



If an assistant grasps the tongue and pulls it forward 

 during each inspiration, it will open the larynx and also 

 stimulate the nerves going to the respiratory center. 



Every person should know how to perform artificial 

 respiration, for it may be the means of saving a life from 

 drowning or from an electric shock. No one should 

 hesitate to attempt artificial respiration in these cases, for 

 even crude and ignorant attempts will result in the entrance 

 of some air and may save a life. 



SUMMARY 



1. The lungs are two organs from which the red blood 



cells obtain oxygen for the use of the cells of the 

 body. 



2. Each lung is made of tiny air sacs which communicate 



freely with the air through the windpipe and nose. 



3. Each lung rests upon a curved muscle called the dia- 



phragm, and is covered by curved ribs. 



4. When the ribs are lifted or the diaphragm depressed, 



air enters the lungs. This is inspiration. 



5. When the muscles relax, the weight of the parts and 



the elasticity of the lungs drive out some of the air. 

 This is expiration. 



6. Inspiration and expiration occur alternately about 



eighteen times a minute. 



7. The movements of the ribs and diaphragm in breath- 



ing are controlled by a small part of the brain just 

 above the spinal cord. 



7. x: 



