How does the kidney respond to an increase in blood acidity?

The kidney plays a crucial role in maintaining acid-base balance in the body, and it responds to an increase in blood acidity by excreting hydrogen ions. When blood becomes more acidic, the kidneys enhance the secretion of hydrogen ions into the urine. This process helps to reduce the acidity of the blood by removing excess hydrogen ions, allowing for a more neutral pH level.

In addition to excreting hydrogen ions, the kidneys can also reabsorb bicarbonate ions to help buffer the acidity, but the primary direct response to increasing acidity is the excretion of hydrogen ions. This adjustment in kidney function is part of a larger homeostatic mechanism to maintain the pH of body fluids within a narrow, optimal range, which is critical for many physiological processes.