NAPLEX (North American Pharmacist Licensure Examination) Practice Exam

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Ace your North American Pharmacist Licensure Examination (NAPLEX) with our comprehensive practice test. Features include interactive flashcards, multiple-choice questions, with detailed hints and explanations. Fast-track your pharmacy career today!

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Which phase of the cardiac action potential represents rapid ventricular depolarization?

  1. Phase 0

  2. Phase 1

  3. Phase 2

  4. Phase 3

The correct answer is: Phase 0

Phase 0 is the correct answer because it represents rapid ventricular depolarization. During this phase, the membrane potential increases as sodium ions enter the cell rapidly. The other options are incorrect because - Phase 1 represents early repolarization, where the membrane potential decreases slightly as potassium ions leave the cell. - Phase 2 represents the plateau phase, where the membrane potential remains relatively constant due to a balance of potassium and calcium ions entering and leaving the cell. - Phase 3 represents rapid repolarization, where the membrane potential decreases quickly as potassium ions continue to leave the cell.