AEMCA Practice Exam

Which component is primarily involved in the physiological buffering system in the blood?

1. Oxygen

2. Carbonic acid

3. Glucose

4. Cholesterol

The correct answer is: Carbonic acid

The physiological buffering system in the blood primarily relies on carbonic acid, which plays a crucial role in maintaining acid-base balance. Carbonic acid forms when carbon dioxide, a byproduct of metabolism, dissolves in the blood. This compound can dissociate into bicarbonate ions and hydrogen ions, which helps to regulate pH levels in the body. When the pH decreases (becoming more acidic), carbonic acid can donate hydrogen ions, effectively acting as a buffer to prevent drastic changes in acidity. Conversely, when the pH increases (becoming more alkaline), bicarbonate can combine with excess hydrogen ions, helping to stabilize the pH. Oxygen, glucose, and cholesterol do not have direct roles in the buffering system. Oxygen is primarily involved in respiration and energy production, glucose serves as a primary energy source for cells, and cholesterol is vital for cell membrane structure and function, as well as for the synthesis of certain hormones. Therefore, carbonic acid is fundamentally essential for physiological buffering in the blood.