Which is a function of the respiratory system related to acid-base balance?

• A. Maintaining homeostasis (acid-base balance) of arterial blood
• B. Digestive enzyme production
• C. Bone remodeling
• D. Oxygen transport to tissues

Answer: (A)

The respiratory system helps keep arterial pH within a narrow range by regulating the level of carbon dioxide in the blood. CO2 reacts with water to form carbonic acid, which dissociates into hydrogen ions and bicarbonate; higher CO2 pushes the reaction to produce more H+, lowering pH, while removing CO2 lowers H+ and raises pH. By adjusting ventilation in response to blood pH and CO2, the lungs actively maintain acid-base balance. The other options are functions of different systems: digestive enzyme production comes from the digestive tract, bone remodeling involves skeletal and mineral processes, and oxygen transport to tissues is primarily a function of the circulatory system aided by the lungs’ oxygen intake, not the acid-base balancing role.