Homework SourseWhat is the effect of vigorous physical activity on the satu
Solution
Answer: (Venous oxygen concentration falls in proportion to the intensity of exercise. The venous O2 concentration and pO2 drop rapidly at the onset of exercise due to increased extraction of O2 by the working muscle)
Increasing the temperature of Hb lowers its affinity for O2 and shifts the oxygen dissociation curve to the right. This has physiological importance during exercise since the temperature of muscle tissue is higher than 37°C, and oxygen can be unloaded from Hb more easily at the higher temperature (lowered oxygen affinity).
Increased H+ activity (decreased pH) also lowers the affinity of Hb for O2. This was originally noticed by Bohr (Bohr effect) and his colleagues as an effect of increased PCO2, but it has been shown to be primarily an effect of pH inside the red blood cell. CO2 by itself, at constant pH, also affects the oxygen dissociation curve such that increased PCO2 shifts the curve to the right (i.e., lowers the affinity of Hb for oxygen).
The Bohr effect is important in exercise. The oxygen dissociation curve is shifted to the right to allow easier unloading of oxygen from Hb in the tissues. The rightward shift in the oxygen dissociation curve is more important at lower PO2. Although the rightward shift interferes with oxygen loading in the lungs, this never causes a problem in oxygen transport.
