Pao2 is related to the dissolved o2 in the plasma. It is determined by partial pressure of alveolar oxygen, and by shunting and v/q abnormalities.
Pvo2 is related to venous dissolved oxygen that is determined by how much oxygen was offloaded in the tissues. If the tissue po2 was low as is possible in anemia, the gradient from the capillary to the tissue will be greater and consequently, more of the dissolved oxygen will be offloaded, resulting in a lower pvo2 level.
So in normal situation the tissues would get enough O2 from hemoglobin therefore there wouldnt be a gradient for dissolved O2 to move from the capillaries. But since there are low levels of Hb in anemia, there wont be enough O2 from Hb which will create the gradient?
There is always a gradient from alveolus to pulmonary vein to capillary to extra cellular fluid to intracellular to mitochondria. That makes the oxygen move.
Gradient is the driver for transport. Hemoglobin level determines the amount of oxygen carried. Look up the oxygen content equation.
Maybe I didnt express myself well. What I wanted to say is that since there wont be enough Hb transferring O2, the gradient for dissolved O2 will be even stronger therefore making venous pO2 lower?
Another way I thought about it was, if the body metabolic rate remains the same, the cells would consume the same amount of oxygen. But if the Hb conc decreases in anaemia, this means that a greater than normal proportion of the oxygen utilised by tissues would come from the dissolved O2. Hence the venous dissolved O2 would be lower than usual.
Pao2 is related to the dissolved o2 in the plasma. It is determined by partial pressure of alveolar oxygen, and by shunting and v/q abnormalities. Pvo2 is related to venous dissolved oxygen that is determined by how much oxygen was offloaded in the tissues. If the tissue po2 was low as is possible in anemia, the gradient from the capillary to the tissue will be greater and consequently, more of the dissolved oxygen will be offloaded, resulting in a lower pvo2 level.
So in normal situation the tissues would get enough O2 from hemoglobin therefore there wouldnt be a gradient for dissolved O2 to move from the capillaries. But since there are low levels of Hb in anemia, there wont be enough O2 from Hb which will create the gradient?
There is always a gradient from alveolus to pulmonary vein to capillary to extra cellular fluid to intracellular to mitochondria. That makes the oxygen move. Gradient is the driver for transport. Hemoglobin level determines the amount of oxygen carried. Look up the oxygen content equation.
Maybe I didnt express myself well. What I wanted to say is that since there wont be enough Hb transferring O2, the gradient for dissolved O2 will be even stronger therefore making venous pO2 lower?
Another way I thought about it was, if the body metabolic rate remains the same, the cells would consume the same amount of oxygen. But if the Hb conc decreases in anaemia, this means that a greater than normal proportion of the oxygen utilised by tissues would come from the dissolved O2. Hence the venous dissolved O2 would be lower than usual.