Question

Unloading of oxygen from hemoglobin is enhanced under the following conditions.

• A. Increase in pH, increase in $C{O}_2$, decrease in temperature
• B. Decrease in pH, increase in $C{O}_2$, increase in temperature
• C. Decrease in pH, decrease in $C{O}_2$, increase in temperature
• D. Increase in pH, decrease in $C{O}_2$, decrease in temperature

Answer 1

The correct option is B Decrease in pH, increase in $C{O}_2$, increase in temperature

Unloading refers to the removal of oxygen from the oxyhemoglobin. As blood flows through the capillaries in our metabolizing tissues, oxygen diffuses out of the red blood cells. Increased temperature decreases the affinity of hemoglobin for oxygen. As oxyhemoglobin is exposed to higher temperatures in the metabolizing tissues, affinity decreases and hemoglobin unloads oxygen. Declining pH (increase acid) results in the increase of O${}_2$ unloading. Increased peripheral tissue metabolism, such as reduced pH, increased CO${}_2$, increased temperature, shift the Oxygen-Hemoglobin dissociation curve to the right, reducing hemoglobin’s affinity for oxygen and thus improving oxygen unloading.