Final answer:
The long length of the cardiac action potential allows for the heart to properly fill with blood by ensuring a complete contraction before another action potential can occur; this is due to the long plateau phase and the prolongation of the refractory period with increased calcium ion influx.the right answer is B
Step-by-step explanation:
The long length of the cardiac action potential, which lasts 200-300 milliseconds, provides a significant benefit to heart function. The correct answer to the question is that this duration allows for B-an opportunity for the heart to fill with blood. During the plateau phase of the cardiac action potential, there is an influx of calcium ions. This results in a prolonged refractory period, ensuring that the heart's contraction is complete before another action potential can occur, which prevents premature contractions and allows sufficient time for the ventricles to fill with blood between beats.
The other options presented are incorrect because a prolonged action potential does not lead to a reduction in strength of contraction, it allows for increased calcium ion entry into cells (not less), and it does not directly cause a faster heart rate. Instead, the extended refractory period is critical for ensuring effective pumping of blood by allowing complete contractions and avoiding premature contractions that would disrupt the cardiac cycle.