AEMCA Practice Exam

What system controls the level of carbonic acid in the body?

1. Pulmonary system

2. Renal system

3. Circulatory system

4. Nervous system

The correct answer is: Pulmonary system

The pulmonary system plays a crucial role in regulating the level of carbonic acid in the body through the control of carbon dioxide (CO2) levels in the blood. When CO2 is produced as a byproduct of metabolism, it can react with water in the body to form carbonic acid. The pulmonary system, primarily through the process of respiration, manages the amount of CO2 that is exhaled. When CO2 levels in the blood rise, the body senses an increase in carbonic acid concentration, leading to a decrease in blood pH (making it more acidic). In response, the respiratory rate can increase, allowing for more CO2 to be expelled. Conversely, if CO2 levels drop, the respiratory rate may decrease, retaining CO2 and thus increasing carbonic acid levels. This feedback loop helps to maintain a balanced pH level in the blood, demonstrating the pulmonary system's essential function in the acid-base equilibrium within the body. While the renal system also contributes to acid-base balance by excreting hydrogen ions and reabsorbing bicarbonate, its effects are not as immediate as those of the pulmonary system. The circulatory system transports CO2 and other gases but does not directly control carbonic acid levels, and the nervous