The Hb-O2 dissociation curve is shifted to left by

2,3-BPG is very plentiful in red cells. It is formed from 3phosphoglyceraldehyde, which is a product of glycolysis the Embden-Meyerhof pathway (Figure 36-4). It is a highly charged anion that binds to the bchains of deoxyhemoglobin. One mole of deoxyhemoglobin binds 1 mol of 2,3-BPG. In effectHbO2 + 2,3-BPG =Hb - 2,3-BPG + O2In this equilibrium, an increase in the concentration of 2,3BPG shifts the reaction to the right, causing more O2 to be liberated. So decrease in 2,3 BPG shift the reaction to leftMetabolic acidosis (or nonrespiratory acidosis) occurs when strong acids are added to blood. If, for example, a large amount of acid is ingested (eg, aspirin overdose) this decrease in pH cause shift to the rightA rise in temperature shifts the curve to the rightThe pH of blood falls as its CO2 content increases so that when the PCO2 rises, the curve shifts to the rightRef: 23rd Edition of Ganong's Review of Medical Physiology 611,615