Describe the carriage of oxygen in the blood, including total oxygen delivery per minute.
Better answers divided oxygen carriage into that bound to haemoglobin and that carried in the
dissolved form. A reasonable amount of detail on the haemoglobin structure and its binding of
oxygen was expected, including an explanation of co-operative binding and the oxygen carrying
capacity of haemoglobin. Better answers mentioned Henry’s law in the description of dissolved
oxygen, along with an estimation of the amount of oxygen that is normally in the dissolved form.
It was expected that answers include the equation for oxygen delivery, a brief description of the
components of that equation and the normal value, which a large number of candidates omitted.
Total DO2 = Cardiac output (L/min) × Oxygen content (ml/L)
Oxygen content = (sO2 × ceHb × BO2 ) + (PaO2 × 0.003), where:
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Lifson, Nathan, et al. "The fate of utilized molecular oxygen and the source of the oxygen of respiratory carbon dioxide, studied with the aid of heavy oxygen."Journal of Biological Chemistry 180.2 (1949): 803-811.
Pittman, Roland N. Chapter 4 - Oxygen Transport; in "The Circulatory System and Oxygen Transport." (2011).
Willem G. Zijlstra. "Misconceptions in reporting oxygen saturation." Anesthesia & Analgesia 105.6 (2007): S5-S9.
Gregory, I. C. "The oxygen and carbon monoxide capacities of foetal and adult blood." The Journal of physiology 236.3 (1974): 625-634.