188
C. ALBERS
K‘ of the buffer substances decreases more than the K‘ of carbonic acid.
Therefore, hydrogen ions recombine with the buffer to increase the
undissociated moiety and more cations are available to form the dissociated salts of the carbonic acid: The chemically bound CO, increases.
In addition, the physically dissolved CO, is increased, too, because the
solubility of gases varies inversely with the temperature (Table 11).
Since the effect of temperature on the physically dissolved CO, is more
pronounced than that on the chemically bound CO,, the denominator in
Eq. (12c) decreases more than does the numerator. Therefore, the pH
must increase.
The effect of temperature on the dissociation constants of carbonic
acid can be seen in Table 11. From the data in Table I1 it is obvious that
pK,’ is affected more than pK,’ especially for salt solutions. Although these
effects are important for the physical chemistry of freshwater and seawater, they are of minor importance for the temperature effect on the
acid-base balance of the blood when compared with the effects of temperature on the solubility of CO, and on the dissociation constants of the
buffer substances.
111. THE TRANSPORT OF CO, IN THE BLOOD
A. The CO, Combining Curve of the Blood
The curve relating the total CO, content of the blood to the CO,
tension is commonly called the CO, dissociation curve of the blood. Since
total CO, comprises physically dissolved CO, as well as chemically bound
C 0 2 , the term “ C 0 2 combining curve” seems to be more appropriate.
Figure 7 shows the CO? combining curves of oxygenated and deoxygenated blood of the salmon and the dogfish. In the region of low CO,
tensions, the curves increase steeply but then gradually flatten out. In
the trout the curves of deoxygenated blood show a higher CO, content
than those of oxygenated blood, whereas no such effect could be demonstrated in the dogfish. As shown by Henderson (1932) for mammalian
blood and by Ferguson et al. (1938) and Albers and Pleschka (1967)
for fish blood, such curves yield straight lines in a limited range of
CO, tensions when plotted in a double logarithmic system. This is
very convenient for practical purposes. Figure 8 shows examples of CO,
combining curves of the blood from various fishes plotted this way.
Obviously, the CO, combining power of the blood, as indicated by these
parameters, varies considerably, There is some correlation between the
C. ALBERS
K‘ of the buffer substances decreases more than the K‘ of carbonic acid.
Therefore, hydrogen ions recombine with the buffer to increase the
undissociated moiety and more cations are available to form the dissociated salts of the carbonic acid: The chemically bound CO, increases.
In addition, the physically dissolved CO, is increased, too, because the
solubility of gases varies inversely with the temperature (Table 11).
Since the effect of temperature on the physically dissolved CO, is more
pronounced than that on the chemically bound CO,, the denominator in
Eq. (12c) decreases more than does the numerator. Therefore, the pH
must increase.
The effect of temperature on the dissociation constants of carbonic
acid can be seen in Table 11. From the data in Table I1 it is obvious that
pK,’ is affected more than pK,’ especially for salt solutions. Although these
effects are important for the physical chemistry of freshwater and seawater, they are of minor importance for the temperature effect on the
acid-base balance of the blood when compared with the effects of temperature on the solubility of CO, and on the dissociation constants of the
buffer substances.
111. THE TRANSPORT OF CO, IN THE BLOOD
A. The CO, Combining Curve of the Blood
The curve relating the total CO, content of the blood to the CO,
tension is commonly called the CO, dissociation curve of the blood. Since
total CO, comprises physically dissolved CO, as well as chemically bound
C 0 2 , the term “ C 0 2 combining curve” seems to be more appropriate.
Figure 7 shows the CO? combining curves of oxygenated and deoxygenated blood of the salmon and the dogfish. In the region of low CO,
tensions, the curves increase steeply but then gradually flatten out. In
the trout the curves of deoxygenated blood show a higher CO, content
than those of oxygenated blood, whereas no such effect could be demonstrated in the dogfish. As shown by Henderson (1932) for mammalian
blood and by Ferguson et al. (1938) and Albers and Pleschka (1967)
for fish blood, such curves yield straight lines in a limited range of
CO, tensions when plotted in a double logarithmic system. This is
very convenient for practical purposes. Figure 8 shows examples of CO,
combining curves of the blood from various fishes plotted this way.
Obviously, the CO, combining power of the blood, as indicated by these
parameters, varies considerably, There is some correlation between the