CardAP — KinFAST

Adaptive test — questions are selected based on your ability estimate. — Tag: SANodeVsMuscleAP

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A physiology student compares the action potentials recorded from a sinoatrial (SA) node pacemaker cell and a ventricular contractile cardiac muscle cell. Which combination of differences best distinguishes these two action potentials?

SA node action potentials have a long plateau phase, while ventricular action potentials lack a plateau entirely SA node action potentials show a slow spontaneous depolarization (pacemaker potential) from Na+ leakage and lack a sustained plateau; ventricular action potentials show rapid Na+ depolarization followed by a prolonged Ca2+-driven plateau before repolarization Both action potentials are nearly identical because all cardiac cells use the same channels and timing SA node cells depolarize via Cl- influx, while ventricular muscle depolarizes via H+ influx

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