What is the oxyhemoglobin dissociation curve?

The oxyhemoglobin dissociation curve is a graph that shows the relationship between the partial pressure of oxygen (pO₂) and the percentage saturation of hemoglobin with oxygen.

The curve is sigmoid (S-shaped) because hemoglobin binds oxygen cooperatively. It helps explain how oxygen is loaded in the lungs and released in body tissues.

Key Point:

• High pO₂ → More oxygen binds to hemoglobin.

• Low pO₂ → Oxygen is released to tissues.

Quick Fact: A right shift of the curve increases oxygen release to tissues, while a left shift increases oxygen binding by hemoglobin.