Which of the following statements concerning the differences between action potentials in skeletal muscle cells and in ventricular cardiac muscle cells is TRUE?

Question

Quizplus · Accepted Answer

Unlike in skeletal muscle cells, after sodium influx through voltage-gated channels occurs in ventricular cells, prolonged influx of calcium from the extracellular fluid occurs. This accounts for the prolonged plateau phase in the cardiac muscle action potential. In skeletal muscle cells, repolarization occurs due to K⁺ efflux, while in cardiac muscle cells, it is due to Ca²⁺ efflux. Option A is incorrect as the resting membrane potential of ventricular cells is closer to the potassium equilibrium potential, not the sodium equilibrium potential. Option B is incorrect as the initial depolarization of ventricular cells is due to sodium influx, followed by a more prolonged calcium influx. Option D is incorrect as cardiac muscle cells have longer action potentials than skeletal muscle cells.

Which of the Following Statements Concerning the Differences Between Action