If respiratory rate decreases, what happens to pH?

If respiratory rate decreases, what happens to pH?

• A. Decrease (more acidosis)
• B. Increase (more alkalosis)
• C. No change
• D. Variable

Answer: (A)

Breathing directly regulates the amount of carbon dioxide in the blood, which is a major driver of acid-base balance. When respiratory rate decreases, ventilation drops, so CO2 isn’t expelled as effectively. CO2 accumulates and combines with water to form carbonic acid, which dissociates to release hydrogen ions. The extra hydrogen ions raise the acidity of the blood, causing pH to fall—this is respiratory acidosis. In the short term, pH decreases; over longer periods, the kidneys can partially compensate by adjusting bicarbonate, but the immediate effect of reduced breathing is lower pH.

Breathing directly regulates the amount of carbon dioxide in the blood, which is a major driver of acid-base balance. When respiratory rate decreases, ventilation drops, so CO2 isn’t expelled as effectively. CO2 accumulates and combines with water to form carbonic acid, which dissociates to release hydrogen ions. The extra hydrogen ions raise the acidity of the blood, causing pH to fall—this is respiratory acidosis. In the short term, pH decreases; over longer periods, the kidneys can partially compensate by adjusting bicarbonate, but the immediate effect of reduced breathing is lower pH.