CVS Practice Test 2026 – The All-In-One Guide to Exam Success!

During phase 2 of the non-pacemaker action potential, a phenomenon known as the plateau phase occurs. This phase is characterized by a balance between inward calcium ion (Ca++) currents and outward potassium ion (K+) currents. Specifically, calcium influx through voltage-gated calcium channels plays a crucial role in maintaining a prolonged depolarization, which is essential for the contraction of cardiac muscle cells. Meanwhile, the outward movement of potassium helps to moderate this depolarization, ensuring that the cell does not immediately return to its resting state.

This balanced activity creates a stable plateau that allows sufficient time for the heart muscle to contract and pump blood effectively before repolarization begins. Such a process is vital for maintaining the efficient rhythmic function of the heart and preventing rapid firing of action potentials that can lead to arrhythmias.