Draw the Hb disocciation curve. Why is it that shape? How is it different in the foetus?

1) Draw and label the axes! x= O₂ partial pressure; y= % saturation/occupancy 2) Sigmoid curve (plateau at 100%) 3) Describe the curve, i.e. rate increases, stays level, then decreases. Shows binding cooperativity (A-level) as saturation increases - 4 binding sites, conformational changes. Think wider - purpose etc. Enables loading and unloading. Can mention the Haldane and Bohr effects. 4) The foetal Hb curve is left-shifted. This shows a greater affinity - reference the placental circulation and why this is necessary