Physiology Philes: HB-O2 dissociation curve

aka BSCC Physiology 002

The haemoglobin-oxygen (Hb-O₂) dissociation curve is a sigmoid curve which relates the partial pressure of oxygen dissolved in the blood to the percentage saturation of haemoglobin.  It allow us to understand how haemoglobin hungrily binds to oxygen in the high partial pressures within the alveoli, but happily gives it up where it’s needed most, at the tissue level.

The key is understanding how haemoglobin works,  and that there is cooperative binding – meaning the more oxygen that attaches to Hb, the more  molecules it binds, and the opposite happens when O2 starts to move away from the Hb molecule. It explains why there is a ‘slippery slope’ once the Hb saturation falls lower than 92%. The video also explains the numbers you need to know to draw the curve, and then looks at some of the physiological and pathological situations that shift the curve.

References

• Varjavand N. The Interactive Oxyhemoglobin Dissociation Curve. Vent World