When does blood move into the coronary arteries?

Blood moves into the coronary arteries primarily during early diastole. This phase occurs immediately after the heart's ventricles have contracted and are beginning to relax. During early diastole, the aortic valve closes, creating a decrease in pressure within the aorta, which allows for a pressure gradient that enables blood to flow back toward the coronary arteries.

The coronary arteries originate from the aorta just above the aortic valve, and when the heart is in diastole, especially during the early phase, the blood can effectively perfuse these arteries as the myocardial walls relax. This is essential for providing oxygenated blood to the heart muscle, allowing for adequate coronary perfusion.

In contrast, options related to late diastole and mid diastole do not capture the most efficient moment for coronary filling. While there is some flow in late diastole, significant inflow occurs primarily early in this phase. End of systole refers to the time when the heart is still contracting, and the aortic valve is open, preventing blood from entering the coronary arteries effectively at that moment. Thus, early diastole is the most accurate answer for when blood moves into the coronary arteries.