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Oxygen–hemoglobin Dissociation Curve | How CO Affects Oxy-Hemoglobin Saturation

Each of hemoglobin’s four heme groups can also bind to carbon monoxide (CO). If this occurs, O2 cannot bind and carbon monoxide poisoning results.

As  image descriptionshown  in the animation, carbon monoxide association with hemoglobin is directly related to the plasma partial pressure of CO (= pCO).
In this simulation, pCO is allowed to increase to from 0.0 – 0.4 mmHg while the pCO2 is maintained at 40 mmHg, which is normal.
At pCO = 0.4 mmHg, the hemglobin is almost image descriptionfully saturated with CO. This pressure is approximately 250 X less than the pO2 needed to fully saturate hemoglobin with O2.

An animation demonstrating carbon monoxide association with hemoglobin is directly related to the plasma partial pressure of CO
An animation demonstrating carbon monoxide association with hemoglobin is directly related to the plasma partial pressure of CO
An animation demonstrating carbon monoxide association with hemoglobin is directly related to the plasma partial pressure of CO
An animation demonstrating carbon monoxide association with hemoglobin is directly related to the plasma partial pressure of CO
An animation demonstrating carbon monoxide association with hemoglobin is directly related to the plasma partial pressure of CO
An animation demonstrating carbon monoxide association with hemoglobin is directly related to the plasma partial pressure of CO
An animation demonstrating carbon monoxide association with hemoglobin is directly related to the plasma partial pressure of CO
An animation demonstrating carbon monoxide association with hemoglobin is directly related to the plasma partial pressure of CO
An animation demonstrating carbon monoxide association with hemoglobin is directly related to the plasma partial pressure of CO
Carbon monoxide association with hemoglobin is directly related to the plasma partial pressure of CO (= pCO).

These data indicate that heme has a much greater affinity for CO than for O2. Therefore, if an individual breathes in a relatively small amount of CO, it will saturate the hemoglobin and prevent O2 from binding. As a result, O2 cannot be distributed as needed to the body’s tissues.

Fully saturated hemoglobin