62 
PHYSIOLOGY: Y. HENDERSON 
Proc. N. a. S. 
THE ADJUSTMENT TO THE BAROMETER OF THE HEMATO- 
RESPIRATORY FUNCTIONS IN MAN 
By Yandell He^ndkRSOn 
Yai^e: University MbdicaIv SchooIv 
Communicated by L. B. Mendel. Read before the Academy, November 10, 1919 
It is well knov^^n that persons living at considerable elevations — such as 
Colorado, the cities in the Andes, et cetera — exhibit distinct functional 
adjustments. The amount of hemoglobin per unit volume of blood is 
increased, and a larger volume of air is breathed per unit mass of oxygen 
absorbed and CO2 eliminated. 
These are functional adjustments and not merely immediate compen- 
sations ; for they are developed slov^rly through days or weeks, and the func- 
tions return to sea level values only very gradually. Thus, to illustrate 
by a single simple test, a man on Pike's Peak, who is acclimated to the 
altitude, can hold his breath for a much shorter time than when living at 
sea level. But on descending from the Peak, and during the first few 
hours thereafter, he can hold it scarcely longer than at the summit. 
There is clear evidence that this condition and the increase of breathing 
are due to a decreased amount of alkali, chiefly NaHCOs, in the blood. 
By the now well-known equation of L. J. Henderson, 
H CO3 ^ ^ _ 
it is evident that, if respiration is to maintain the same Ch in the blood 
at an altitude that it does at sea level, the amount of CO2 in solution 
in the blood must be reduced in proportion to the alkali. This is ac- 
complished by an inversely proportional alteration, that is, an increase, 
of breathing. 
It is generally supposed that under oxygen deficiency acids are produced 
in the tissues and retained in the blood, and that the alkali is thus neu- 
tralized and then eliminated through the urine. 
Experiments on dogs by Dr. H. W. Haggard and myself, however, show 
that the processes involved are in many respects exactly the opposite of 
this supposition. Our experiments demonstrate that, before any con- 
siderable amount of alkali is lost, an abnormally large amount of CO2 
is eliminated by the excessive breathing induced by a lowered oxygen 
pressure in the air breathed. Then alkali passes out of the blood to com- 
pensate this alkalosis. 
Thus the process is exactly the opposite of that occurring in other ex- 
periments which we have performed, in which acid was administered in- 
travenously, and in which, therefore, the alkali was lowered first and the 
CO2 in solution was lowered only secondarily.^ Under low oxygen the 
lowering of the dissolved C02(H2C03) is primary, and that of the alkali 
secondary. 
