BIOLOGY IN HUMAN AFFAIRS 



the hydrogen-ion concentration of the body fluids beyond 

 normal limits, the person has acidosis. The human body 

 is equipped with a remarkably efficient mechanism for 

 regulating the relationship between acids and alkalis. 

 The mechanism includes, first of all, the lungs, which 

 rid the body of large amounts of acid in the form of carbon 

 dioxide. The second part of the mechanism is the kidneys, 

 which dispose of acid by excreting it in the fluids which 

 pass out of the body. The third part is the salt content 

 of the blood and of the tissues, which can take up limited 

 amounts of acid or alkali with a view to maintaining the 

 reaction of the blood at a constant point. This salt content 

 is called a buffer mixture, because it acts as a buffer between 

 the upper and lower limitations of danger in relationship 

 to the reaction of the blood. 



Anyone with even a simple knowledge of machinery 

 or mechanics will realize, therefore, that the human 

 system is constructed with factors of safety against most 

 ordinary disturbances. Conditions may arise, however, 

 in which the buffers are used up; and reactions then occur 

 which are unfavorable. In the presence of an insufficient 

 amount of fluid or water, acidosis can develop, although 

 such acidosis is very mild and is corrected by normal 

 physiological reactions. 



When acidosis becomes severe, nervousness, headache, 

 irritability, nausea, weakness, and sleeplessness develop. 

 The person seems short of breath and breathes with diffi- 

 culty. At first he may be flushed and excited, but later, 

 pale and exhausted. Sometimes there is a fruity odor to 

 the breath, although this usually represents an advanced 

 condition. 



In some diseases, such as diabetes or Bright's disease, 

 in very high fever, with profuse diarrhea, and with diffi- 

 culty in the elimination of carbon dioxide in the lungs — 

 such as occurs in pneumonia and heart disease — acidosis 



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