Which change in pCO2 causes a right shift in the oxygen dissociation curve?

An increase in pCO2 causes a right shift in the oxygen dissociation curve due to the physiological effects associated with elevated levels of carbon dioxide in the blood. When pCO2 rises, it leads to an increase in hydrogen ion concentration (lowering the pH), a condition known as acidosis.

This shift in the curve indicates that hemoglobin's affinity for oxygen decreases, facilitating oxygen release to the tissues that are in greater need during states of increased metabolism or hypoxia. This is an important adaptive response because tissues like muscles generate more CO2 during excessive activity, which could lead to oxygen depletion.

Additionally, this rightward shift can be understood through the Bohr effect, where carbon dioxide and hydrogen ions stabilize the deoxygenated form of hemoglobin, promoting oxygen release. Thus, in scenarios such as high-intensity exercise or respiratory diseases where CO2 levels are elevated, the body effectively utilizes this mechanism to ensure oxygen is delivered adequately where required.