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Oxygen Binding Plasma
Llama guanaco

48.13 Oxygen-Binding Adaptations The different hemoglobins and myoglobin have different oxygen-binding properties adapted to different circumstances.The hemoglobin of llamas, for example, is adapted for binding O2 at high altitudes, where Pq2 is low.

their hemoglobin can become saturated with O2 at lower Po2 values than those of other mammals.

pH. The oxygen-binding properties of hemoglobin are also influenced by physiological conditions. The influence of pH on the function of hemoglobin is known as the Bohr effect. As blood passes through metabolically active tissue such as exercising muscle, it picks up acidic metabolites such as lactic acid, fatty acids, and CO2, and blood pH falls. The excess H+ ions bind preferentially to deoxygenated hemoglobin and decrease the affinity of that hemoglobin for O2. As a result, the oxygen-binding curve of hemoglobin shifts to the right. This shift means that the hemoglobin will release more O2 in tissues where pH is low—another way that O2 is supplied where and when it is most needed.

2,3 bisphosphoglyceric acid. BPG is a metabolite of glycolysis (see Figure 7.6). Mammalian red blood cells have a high concentration of BPG, which serves as an important regulator of hemoglobin function. BPG, like excess H+ ions, revers-ibly combines with deoxygenated hemoglobin and lowers its affinity for O2. The result is that at any Po2, hemoglobin releases more of its bound O2 than it otherwise would. In other words, BPG shifts the oxygen-binding curve of mammalian hemoglobin to the right. When humans go to high altitudes, or when they cease being sedentary and begin to exercise, the level of BPG in their red blood cells goes up and makes it easier for the hemoglobin to deliver more O2 to the tissues. The reason that fetal hemoglobin has a left-shifted hemoglobin-O2 binding curve is that the y-globin chains of fetal hemoglobin have a lower affinity for BPG than do the P-globin chains of adult hemoglobin.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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