What happens to the pH of the body as CO\(_2\) levels increase?

• A. The pH decreases, making the blood more acidic.
• B. The pH increases, making the blood more basic.
• C. The pH remains unchanged.
• D. The pH fluctuates randomly.

Answer: (A)

Verified step by step guidance

1. Understand the relationship between CO\(_2\) levels and pH: CO\(_2\) reacts with water in the body to form carbonic acid (H\(_2\)CO\(_3\)), which dissociates into hydrogen ions (H\(^+\)) and bicarbonate ions (HCO\(_3^-\)). This process is described by the equation: CO\(_2\) + H\(_2\)O ⇌ H\(_2\)CO\(_3\) ⇌ H\(^+\) + HCO\(_3^-\).
2. Recognize that an increase in CO\(_2\) levels shifts the equilibrium of the reaction to produce more H\(^+\) ions, as per Le Chatelier's principle. This increase in H\(^+\) ions lowers the pH, making the blood more acidic.
3. Recall that pH is a measure of hydrogen ion concentration, where lower pH values correspond to higher concentrations of H\(^+\) ions and greater acidity.
4. Eliminate incorrect options: The pH does not increase (making the blood more basic), remain unchanged, or fluctuate randomly. These options contradict the biochemical mechanism of CO\(_2\) affecting pH.
5. Conclude that as CO\(_2\) levels increase, the pH decreases, making the blood more acidic. This is a key concept in understanding respiratory acidosis, a condition caused by elevated CO\(_2\) levels.