Acid-base homeostasis · USMLE Step 1

What is the normal physiological arterial blood pH range maintained by acid–base homeostasis in humans?

  1. 7.25–7.35
  2. 7.30–7.40
  3. 7.35–7.45
  4. 7.40–7.50
Show answer and explanation

Correct answer: 7.35–7.45

Normal arterial pH is tightly regulated and typically falls between 7.35 and 7.45; values below 7.35 are considered acidemia, above 7.45 alkalemia.

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