Oxyhemoglobin dissociation curve

The oxygen-hemoglobin dissociation curve correlates the oxygen saturation of hemoglobin across a range of oxygen pressures. The solid black line shows the curve for normal adult hemoglobin (Hb A). Notable points on the curve include:

p50 — The p50 is the pressure at which hemoglobin is 50% saturated (27 mmHg on the X-axis).
Arterial blood — Hemoglobin is approximately 100% saturated at an oxygen pressure of 100 mmHg.
Venous blood — Hemoglobin is approximately 75% saturated.

Conditions that shift the curve may affect oxygen delivery to the tissues; these effects are most pronounced at low partial pressures of oxygen:

Left shift — Conditions that shift the curve to the left (dashed red line) increase the oxygen affinity; hemoglobin holds more tightly onto oxygen and delivers less oxygen to the tissues at a given arterial oxygen pressure. The left-shifted curve for Hb F is what allows transfer of oxygen from the maternal to the fetal circulation.
Right shift — Conditions that shift the curve to the right (dashed blue line) decrease oxygen affinity; hemoglobin holds less tightly onto oxygen and delivers more oxygen to the tissues at a given arterial oxygen pressure.

Hb: hemoglobin; O₂: oxygen gas; Hb F: fetal hemoglobin; R state: relaxed state of hemoglobin; T state: tense state of hemoglobin.

* The ferric hemes of methemoglobin do not bind oxygen, but they increase the oxygen affinity of the normal ferrous heme in the hemoglobin tetramer, shifting the curve left. With high methemoglobin levels, oxygen saturation will be low for a physiologic PaO₂ due to inability of ferric heme to bind oxygen, shifting the curve right.

Graphic 81216 Version 16.0

خرید پکیج

Oxyhemoglobin dissociation curve