In the context of acid-base balance, how does hyperventilation affect blood pH?

• A. It decreases blood pH (respiratory acidosis) by increasing arterial $P_{C{O}_2}$.
• B. It increases blood pH (respiratory alkalosis) by decreasing arterial $P_{C{O}_2}$.
• C. It decreases blood pH by decreasing plasma $H_{{+}^1}$ concentration.
• D. It has no significant effect on blood pH because ventilation does not influence carbonic acid levels.

Answer: (B)

Verified step by step guidance

1. Understand that blood pH is influenced by the concentration of hydrogen ions (H\+), which is closely related to the levels of carbon dioxide (CO\_2) in the blood due to the bicarbonate buffer system.
2. Recall the chemical equilibrium: CO\_2 + H\_2O \leftrightarrow H\_2CO\_3 \leftrightarrow H\+ + HCO\_3\-, where CO\_2 reacts with water to form carbonic acid, which dissociates into hydrogen ions and bicarbonate.
3. Recognize that hyperventilation causes an increased rate of breathing, which leads to excessive exhalation of CO\_2, thereby decreasing the partial pressure of CO\_2 (P\_CO\_2) in arterial blood.
4. Since P\_CO\_2 decreases, the equilibrium shifts to reduce hydrogen ion concentration, resulting in a rise in blood pH (making it more alkaline), a condition known as respiratory alkalosis.
5. Therefore, hyperventilation increases blood pH by decreasing arterial P\_CO\_2, which reduces hydrogen ion concentration and shifts the acid-base balance toward alkalinity.