How do kidneys help compensate for respiratory acidosis?

• A. By excreting more bicarbonate
• B. By increasing hydrogen ion excretion
• C. By retaining potassium
• D. By exchanging sodium for hydrogen ions

Answer: (B)

The kidneys play a critical role in maintaining acid-base balance in the body, particularly in compensating for conditions like respiratory acidosis. In respiratory acidosis, there is an accumulation of carbon dioxide in the blood due to inadequate ventilation, leading to a decrease in blood pH (making it more acidic).

To counter this, the kidneys respond by increasing the excretion of hydrogen ions. This process helps reduce acidity in the blood and thereby raises the blood pH back towards normal levels. Essentially, by excreting more hydrogen ions into the urine, the kidneys promote a more alkaline environment in the bloodstream, which compensates for the acidosis caused by respiratory issues.

This renal compensation occurs over a longer time frame compared to respiratory compensation, which adjusts rapidly through changes in breathing rate. The kidney's ability to manage hydrogen ion concentration is a vital part of maintaining overall acid-base homeostasis in the body. The other options do not directly address the mechanism by which the kidneys compensate for respiratory acidosis.