BIOC34H3 Lecture Notes - Lecture 13: Polycythemia, Hemoglobin, Nfkb1
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We can quantify the binding of oxygen to haemoglobin using an oxygen equilibrium (or disassociation) curve, which plots the partial pressure of oxygen in mmhg on the x-axis. It is relatively flat at the lowest po2 levels and then becomes quite steep before reaching a plateau at higher po2 levels. The sigmoidal nature of this curve results from positive cooperativity, in which the binding of one o2 molecule to a hb subunit facilitates the binding of a second, and so on. The p50 value: quantifying oxygen haemoglobin binding affinity. The variable that is used to quantify the affinity of haemoglobin for oxygen is called the p50. It is defined as the partial pressure of oxygen at which 50% of haemoglobin is bound with oxygen. If we plot concentration on the y-axis, then the p50 value is defined as the point when the oxygen content of the blood if 50% of its maximum value.