42 PHYSIOLOGY FOR NURSES 



If part of the lung is occupied by a foreign substance, 

 as in pneumonia, the respiratory efforts are made more 

 frequently because there is more C0 2 in the blood and 

 the center is stimulated to greater activity. If there is 

 too little C0 2 , the center is less excited and the number 

 of inspirations per minute will decrease, to rise again 

 as soon as the proper amount of C0 2 is restored. 



