Shift to right in Oxygen dissociation curve is seen in all except: March 2007
**Core Concept**
The oxygen dissociation curve illustrates the relationship between the partial pressure of oxygen (pO2) and the percentage of hemoglobin saturated with oxygen. A shift to the right indicates a decrease in the affinity of hemoglobin for oxygen, facilitating the release of oxygen to tissues. This shift is crucial in adapting to changes in oxygen demand and availability.
**Why the Correct Answer is Right**
A shift to the right in the oxygen dissociation curve occurs due to several factors, including increased temperature, decreased pH (acidosis), increased carbon dioxide (CO2) levels, and increased 2,3-bisphosphoglycerate (2,3-BPG) levels. These factors decrease the affinity of hemoglobin for oxygen, allowing it to release oxygen more easily to tissues. The Bohr effect describes the relationship between pH and hemoglobin's affinity for oxygen, demonstrating that a decrease in pH (increase in hydrogen ions) leads to a decrease in hemoglobin's affinity for oxygen.
**Why Each Wrong Option is Incorrect**
**Option A:** Not relevant to the question. Temperature, pH, CO2 levels, and 2,3-BPG levels are factors that cause a shift to the right.
**Option B:** Not relevant to the question. Hemoglobin's affinity for oxygen does not directly relate to the question.
**Option C:** Not relevant to the question. The Fick principle is related to the measurement of blood flow, not the oxygen dissociation curve.
**Option D:** Not relevant to the question. The oxygen-hemoglobin dissociation curve is a graphical representation of the relationship between pO2 and the percentage of hemoglobin saturated with oxygen, not a direct measurement of oxygen consumption.
**Clinical Pearl / High-Yield Fact**
A notable clinical correlation is the effect of high-altitude exposure on the oxygen dissociation curve. At high altitudes, the partial pressure of oxygen is lower, and the body adapts by increasing 2,3-BPG levels, which causes a right shift in the oxygen dissociation curve, facilitating the release of oxygen to the tissues.
**Correct Answer: D.**