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V 



Circulation 



IT seems but yesterday when men spoke with bated breath of the "great 

 killers" such as the black death, typhoid fever, diphtheria, and tuberculo- 

 sis. At the present time we are hearing more and more about heart disease 

 and its leadership in the decimation of mankind. Many believe that a large 

 part of the increase in disorders of the circulatory system is due to the in- 

 creased nervous strain of modern living and the inability of the system to 

 repair itself fast enough. Whatever the reason, medical men are alarmed at 

 the trend. 



As the late Dr. Alexis Carrel pointed out — man is delicate. Every year, 

 in the United States, there are about 100,000,000 illnesses, serious or slight. 

 In the hospitals, 700,000 beds are occupied every day of the year. The 

 care of these patients requires the efforts of 145,000 doctors, 280,000 

 nurses, 60,000 dentists, and 150,000 pharmacists. It also necessitates 7,000 

 hospitals, 8,000 clinics, and 60,000 pharmacies. The public spends annually 

 $715,000,000 on medicines. Medical care, under all its forms, costs about 

 $3,500,000,000 yearly. 



As the viruses, bacteria and other infectious agents are gradually but 

 inexorably brought under control, the degenerative diseases are allowed 

 to show their full potentiality and this is one of the reasons why the afflic- 

 tions of the heart have inched their way upward into a position of leader- 

 ship. Medical science now has another very real and difficult problem to 

 solve. 



THE HEART AND CIRCULATION * 



A. J. CARLSON AND V. JOHNSON 



Grossly, blood appears to be a homogeneous, red, viscous fluid. But 

 microscopically, one can see that it is composed of discrete particles sus- 

 pended in a watery fluid. The particles, called the formed elements, con- 

 sist of the red blood cells, the white blood cells, and the platelets. These 

 may be separated from the fluid portion, or plasma, simply by allowing 

 blood, treated to prevent clotting, to stand in a tube. The formed ele- 



• Reprinted from Machinery of the Body, revised edition, by A. J. Carlson and 

 V. Johnson by permission of the University of Chicago Press. Copyright 1941. 



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