. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. 314 Comparative Animal Physiology more resistant to low oxygen than older birds because of the greater affinity for oxygen.'-" , . i i The blood of the bullfrog tadpole becomes saturated with oxygen at lower tensions than does the blood of the adult frog; the tadpole dissociation curve also is more hvperbolic. Changes in pH alter the shape as well as the position of the dissociation curves of the blood of the frog and tadpole.^'- In the tad- pole the curve moves slightly to the left when pH is decreased, wh
. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. 314 Comparative Animal Physiology more resistant to low oxygen than older birds because of the greater affinity for oxygen.'-" , . i i The blood of the bullfrog tadpole becomes saturated with oxygen at lower tensions than does the blood of the adult frog; the tadpole dissociation curve also is more hvperbolic. Changes in pH alter the shape as well as the position of the dissociation curves of the blood of the frog and tadpole.^'- In the tad- pole the curve moves slightly to the left when pH is decreased, whereas in the adult the tensions of loading and unloading are raised as in other animals. Hemoglobin of terrapin embryos also has a higher Oo affinity, that is, a lower t,. o „, than the hemoglobin of ;'^ Hemoglobins of embryos m general. lO 20 30 40 PARTIAL PRESSURE CO, IN mm H3 Fig. 71. Effects of CO^. on the O, tension for half saturation of blood. © alligator, Dill and Edwards"; O t^ana temporaria, Rana esctilenta, Wolvekamp^*''; A toadfish, + mackerel, Root'"; * carp, Black and Irving'"; IX bowfin, © sucker, p^ brook trout, ^ cathsh. Black'"'; {J paku, Willmer.'" arc, therefore, functional at lower oxygen tensions than are adult hemoglobins. Relation of Blood Pigments to Distribution of Amphibians and Fishes. C3xygen dissociation curves for a number of amphibia arc shown in Figure 76. Those genera which spend much of their time on land show oxygen dissociation curves to the right of the curves for aquatic forms; , the loading tensions are higher with greater availability of oxygen. The curve of Crypto- branchiis may represent a reversion hom land to ;^ Similarly, in a series of seven species of turtles, the terrestrial box turtle has the lowest oxygen affinity (tj/^ hui= mm. Hg), whereas aquatic turtles have higher O2. Please note that these images are extracted from scanned page images that may have been digitally
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