ACIDOSIS 557 



that we may have degrees of acidity and alkalinity in the cells which 

 are quite different from those in the blood. 



As pointed out especially by Henilerson," the normal reaction of 

 the body is kept practically constant chiefly by: 1. The salts of (.'O2 

 and H3PO4, existing in such proportions of carbonate, bicarbonate and 

 carbonic acid, or disodium- and monosodium-hydrogen-phosphate, 

 as to produce an almost neutral solution. These being salts of weak 

 acids with strong bases it follows that when a stronger acid, such as 

 lactic or butyric, combines with the bases there is only the weak acid 

 liberated and hence the influence of the strong acid on the blood reac- 

 tion is greatly reduced. (2) The acid most abundantly formed in 

 metabolism, COo, is volatile and hence is rapidly excreted by the lungs 

 without withdrawing bases from the blood. (3) The kidneys can 

 eliminate the other buffer acid, PO4, with l)ut a minimum of base at- 

 tached in the form of NaH2P04; and they also remove the' basic 

 product of metabolism, ammonia. By the combined influence of these 

 factors the acids formed in metabolism are passed out with a maxi- 

 mum rapidity and with a minimum alteration in the reaction of the 

 fluids by which they are carried through the body. In addition to 

 these we have, as mentioned before, the capacitj^ of the proteins to 

 combine with both acids and alkalies, the reserve neutrahzing capacity 

 of ammonia formed in metabolism, and also the enormous reserve supply 

 of bases in the bone salts. So effective is this mechanism that accu- 

 rate determination of the H-ion concentration of the blood shows that 

 very rarely is there more than the slightest deviation from the normal 

 proportion of free H and OH ions, which is slightly on the alkaline side 

 of exact neutrality. This neutrality is one of the most fixed of all the 

 constants of the body. 



Acidosis, therefore, is a condition in which the essential feature is 

 not an actual acidity of the blood, but the impoverishment of the body 

 in available bases, whereby there results a decreased capacity of the 

 tissues to get rid of CO2 and other acids formed in their metabolism. 

 This reduction in bases may be, and most usually is, the result of 

 excessive production of acids, in excreting which the bases are elimi- 

 nated in excess, but it may also result from deficient capacity of the 

 kidneys to excrete acids, since the kidneys plaj' an important role in 

 regulating acidity. Macleod^^ summarizes the conditions that might 

 give rise to changes in the hj'drogen ion concentration in the blood 

 (Ch) as follows : 



Increase of Ch. 

 Addition or accumulation Accumulation of CO2 (asphyxial conditions). In- 

 0/ acid complete oxidation of carbohydrate (lactic acid in 



muscular exercise). 

 Defective oxidation of fat (ketosis). 

 Renal insufficiency (nephritis). 

 Decomposition of protein (as in acidosis of fever). 

 Intestinal fermentation. 

 Administration of acid (experimental). 



*^ See Harvey Society Lectures, 1914-5. 



" See reviews by Frothingham, Arch. Int. Med. 1916 (18) 717; ^klacleod, Jour. 

 Lab. Clin. Med., 1919 (4), 315. 



