Which organ is responsible for controlling blood pH levels?

The kidneys play a crucial role in regulating blood pH levels by managing the balance of acids and bases in the body. They accomplish this through the process of reabsorption and secretion of certain ions, primarily hydrogen ions (H+) and bicarbonate ions (HCO3-). When the blood becomes too acidic, the kidneys can excrete more hydrogen ions and reabsorb bicarbonate, which helps to raise the pH back to a more neutral level. Conversely, if the blood is too alkaline, the kidneys can retain hydrogen ions and excrete bicarbonate to lower the pH.

This renal regulation is vital for maintaining homeostasis, as the body's enzymatic and metabolic processes typically function optimally within a narrow pH range (around 7.35 to 7.45). Other organs like the liver and pancreas also play important roles in metabolic processes but do not directly influence blood pH regulation in the same way the kidneys do. The heart is primarily involved in the circulatory system, ensuring blood is pumped throughout the body but does not directly regulate pH levels.