2IO APPLIED PHYSIOLOGY 



359. Amount of oxygen used daily. The amount of 

 oxygen used in the body is constantly varying. During 

 muscular exertion greater power is required than when the 

 body is at rest. To keep up the increased power, more 

 oxygen must leave the blood and unite with the muscle 

 cells. During sleep less oxygen is needed, but the average 

 amount used each day is fairly constant. 



It is a simple example in arithmetic to calculate how much oxygen 

 the red blood cells usually carry. 

 1 8 = no. of respirations per minute. 



30 = no. of cubic inches of air in each inspiration. 

 540 = no. of cubic inches of air inspired each minute. 



60 

 32400 = no. of cubic inches of air inspired each hour. 



.04 = per cent of air which enters the red blood cells as oxygen. 

 1296 = no. of cubic inches of oxygen entering the blood each hour. 

 1296-:- 1 728 = 0.75= cubic feet of oxygen entering the blood each hour. 



0.75 



1.2 = ounces weight of a cubic foot of oxygen. 



0.9 = ounces of oxygen entering the blood each hour. 



24 

 21.6 = ounces of oxygen entering the blood each day. 



Allowing two or three ounces more for extra exertions, about 25 

 ounces of oxygen enter the body each day. This is about the amount 

 needed to oxidize the food which a man usually eats. 



The amount of carbonic acid given out is about the same as the 

 amount of oxygen taken in, if it is measured in cubic inches. But since 

 the carbonic acid is heavier, it amounts to about 30 ounces a day. About 

 20 ounces of water are also breathed out each day. 



360. Effect of exercise upon the amount of oxygen 

 absorbed. In quiet breathing each red blood cell is 

 loaded with oxygen to its full capacity. During muscular 

 exertion the heart beats more forcibly and faster, driving 

 the red blood cells more rapidly, and thus, in a given time, 

 more oxygen will be carried. But when the cells are shot 



