Which cells exhibit an action potential characterized by both a spike and a plateau phase?

The action potential characterized by both a spike and a plateau phase is a distinctive feature of cardiac muscle cells. This plateau phase is crucial for the function of the heart, as it helps to ensure that the contraction lasts long enough to effectively pump blood. During the action potential in cardiac muscle cells, the rapid influx of sodium ions leads to a sharp rise in voltage (the spike) followed by a prolonged phase where calcium ions enter the cells, which prolongs depolarization. This plateau prevents the heart from entering tetany, allowing it to relax between beats and maintain a rhythmic contraction.

In contrast, peripheral sensory and motor nerve cells, as well as striated skeletal muscle cells, typically exhibit action potentials that do not include a significant plateau phase. Their action potentials are usually faster and more transient, designed for rapid signaling and movement rather than the sustained contraction seen in cardiac tissues. Thus, cardiac muscle cells are the only option that correctly describes this unique characteristic of action potential.