PROBLEM 4. How the Cells Are Provided with Oxygen 



the individual cells. This continues for 

 some time even though the amount de- 

 livered is very much smaller. As long as 

 the heart muscle has enough oxygen to 

 keep contracting the person has a chance 

 to survive. When breathing has been 

 stopped, the small supply of oxygen in 

 the body must be added to as rapidly as 

 possible. We must try to get fresh air 

 into the air sacs by means of "artificial 

 respiration." As more oxygen diffuses 

 from air sacs into blood the body cells 

 gradually begin to work more actively. 

 In time the breathing mechanism again 

 starts up. But all this may take a long 

 time. For this reason artificial respiration 

 must be continued, sometimes for several 

 hours, until the person again begins nat- 

 ural breathing, or until a physician de- 

 clares the case hopeless. 



Artificial respiration may be given 

 without apparatus in one of two ways. 

 The Shaefer prone pressure method is 

 perhaps the better known of these meth- 

 ods. The patient is placed on his stomach 

 with his face turned to one side. The 

 first aider straddles him (see Fig. 231). 

 Pressure is applied to the lower ribs 

 gently but firmly and rhythmically at 

 the rate of 16 times a minute. In another 

 method the patient is placed on his back 

 on a board or stretcher and rocked in a 

 seesaw fashion up and down 16 times a 

 minute. The rocking must be sudden 

 but gentle. The abdominal organs press 

 against the diaphragm regularly and thus 

 reestablish the breathing movements. 

 Everyone should learn to use the Shaefer 

 method of artificial respiration. The Red 

 Cross, the Y.M.C.A., the Y.W.C.A., Boy 

 and Girl Scouts, and various other agen- 

 cies provide such instruction. 



233 



Altitude troubles. Air pressure gets 

 lower the higher you rise above sea level. 

 This affects fliers in two important ways. 

 There is much nitrogen carried in the 

 blood and in the body fluids. This is 

 neither helpful nor harmful under normal 

 circumstances. It is present merely be- 

 cause nitrogen forms 79 per cent of the 

 atmosphere at sea level, and by diffusion 

 it enters the blood. When a flier ascends 

 rapidly to a region where the air pressure 

 and therefore the nitrogen pressure is 

 lower the nitrogen forms bubbles in the 

 blood and in other body fluids. These 

 bubbles cause pain, may cause paralysis 

 and even death. This condition is called 

 the "bends." The formation of bubbles 

 in the blood is similar to the formation 

 of bubbles in a bottle of soda water when 

 the pressure is lowered by removing the 

 cap. "Bends" was known before the days 

 of high flying; deep sea divers and other 

 men who worked under high pressures 

 and later changed too quickly to normal 

 air pressure met the same difficulty. The 

 flier can overcome the bends by inhaling 

 pure oxygen before his flight. In one 

 hour he can rid himself of half the nitro- 

 gen in his body, thus preparing himself 

 for his ascent. But often fliers must take 

 off at a moment's notice without such 

 preparation. Some large planes have pres- 

 sure-sealed cabins that maintain a suit- 

 able air pressure no matter how high the 

 plane goes. 



Another result of high altitude flying 

 is known as mioxia (an'-ox'-ia), which 

 means a lack of sufficient oxygen. Above 

 10,000 feet the air is so rarefied that the 

 amount of oxygen is too small to pro- 

 vide for sufficient diffusion into the 

 blood. Corpuscles passing through the 



