Question

Describe oxygen-haemoglobin dissociation curve.

Answer 1

The oxygen dissociation curve is a graph that plots the proportion of haemoglobin in its oxygen-laden saturated form on the vertical axis against the partial pressure of oxygen on the horizontal axis. This curve is an important tool for understanding how our blood carries and releases oxygen. The curve is usually best described by a sigmoid plot. A hemoglobin molecule can bind up to four oxygen molecules in a reversible way. The shape of the curve results from the interaction of bound oxygen molecules with incoming molecules. Hemoglobin's affinity for oxygen increases as successive molecules of oxygen bind. More molecules bind as the oxygen partial pressure increases until the maximum amount that can be bound is reached. As this limit is approached, very little additional binding occurs and the curve levels out as the hemoglobin becomes saturated with oxygen. Hence the curve has a sigmoidal or S-shape.