Final answer:
The atria fill with blood and the ventricles are empty immediately after the second heart sound; murmurs hint at potential valve issues.
Step-by-step explanation:
Immediately after the second heart sound, the atria are filling with blood, and the ventricles are empty. Abnormal heart sounds, or murmurs, usually indicate valve problems. During this phase of the cardiac cycle, the atria are in diastole, a phase of relaxation and filling with blood, while the ventricles are in systole, having just completed contraction and ejected blood through the semilunar valves. A murmur is often the result of turbulent blood flow, which can be caused by a variety of valvular issues, ranging from stenosis (narrowing of the valve) to regurgitation (backflow of blood due to improper valve closure).