Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Oxygen dissociation curve describes the relationship between the partial pressure of oxygen (pO2) and hemoglobin saturation. It is essential for understanding how oxygen is transported and released by red blood cells.
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The shape of the curve is sigmoidal (S-shaped) due to cooperative binding of oxygen to hemoglobin.
A rightward shift in the curve indicates decreased affinity of hemoglobin for oxygen, often caused by increased CO2, H+, temperature, or 2,3-BPG levels.
A leftward shift indicates increased affinity for oxygen, which can be caused by decreased CO2, H+, temperature, or 2,3-BPG levels.
At high pO2 levels (such as in the lungs), hemoglobin binds to oxygen more readily; at low pO2 levels (such as in tissues), it releases oxygen more easily.
The P50 value on the curve represents the partial pressure at which hemoglobin is 50% saturated with oxygen and serves as an indicator of hemoglobin's affinity for oxygen.