How does the body respond to respiratory alkalosis?

• A. The body compensates by increasing respiratory rate.
• B. The body compensates by increasing urinary loss of bicarbonate.
• C. The body compensates by decreasing heart rate.
• D. The body compensates by retaining carbon dioxide.

Answer: (B)

In respiratory alkalosis, the pH of the blood becomes elevated due to a decrease in carbon dioxide levels, often resulting from hyperventilation. The body attempts to compensate for this condition through various mechanisms aimed at restoring acid-base balance.

One primary way the body compensates is by increasing urinary loss of bicarbonate. When blood pH rises, the kidneys can respond by excreting more bicarbonate into the urine. This action helps to decrease bicarbonate levels in the blood, which ultimately lowers the pH back toward normal. By facilitating the loss of bicarbonate, the kidneys contribute to correcting the alkalotic state.

The other options do not accurately depict the compensatory response to respiratory alkalosis. For instance, increasing respiratory rate would exacerbate the condition rather than relieve it, while decreasing heart rate typically doesn't play a direct role in respiratory alkalosis compensation. Additionally, retaining carbon dioxide would counteract the alkalosis but is not a direct renal response; the primary renal mechanism is the urinary excretion of bicarbonate.

In summary, the correct compensatory response to respiratory alkalosis involves the kidneys increasing urinary bicarbonate excretion, making option B the appropriate choice.