During which phase of the cardiac cycle do the coronary arteries fill?

During which phase of the cardiac cycle do the coronary arteries fill?

• A. Early Diastole
• B. Late Diastole
• C. During Systole
• D. During Atrial Contraction

Answer: (A)

The correct answer is early diastole because this is the phase of the cardiac cycle when the heart muscle relaxes, allowing the chambers of the heart to fill with blood. During this relaxation phase, the pressure in the aorta decreases, leading to a pressure gradient that facilitates blood flow into the coronary arteries, which supply the heart muscle with oxygen-rich blood. As the ventricles relax, the aortic valve closes, preventing backflow from the aorta into the ventricles. This closure maintains a pressure in the aorta that allows blood to flow into the coronary arteries. The filling of the coronary arteries primarily occurs during the early diastolic phase since this is when the heart is least contracted and more blood flow is directed towards the coronary arteries to provide adequate oxygenation to muscle tissues. In contrast, during late diastole, while the heart is still filling with blood, much of the coronary perfusion has already occurred. Systole, which is the contraction phase, primarily focuses on ejecting blood from the heart rather than filling the coronary arteries. Atrial contraction occurs towards the end of diastole and aids in filling the ventricles, but it does not play a significant role in the primary filling of the coronary arteries.

The correct answer is early diastole because this is the phase of the cardiac cycle when the heart muscle relaxes, allowing the chambers of the heart to fill with blood. During this relaxation phase, the pressure in the aorta decreases, leading to a pressure gradient that facilitates blood flow into the coronary arteries, which supply the heart muscle with oxygen-rich blood.

As the ventricles relax, the aortic valve closes, preventing backflow from the aorta into the ventricles. This closure maintains a pressure in the aorta that allows blood to flow into the coronary arteries. The filling of the coronary arteries primarily occurs during the early diastolic phase since this is when the heart is least contracted and more blood flow is directed towards the coronary arteries to provide adequate oxygenation to muscle tissues.

In contrast, during late diastole, while the heart is still filling with blood, much of the coronary perfusion has already occurred. Systole, which is the contraction phase, primarily focuses on ejecting blood from the heart rather than filling the coronary arteries. Atrial contraction occurs towards the end of diastole and aids in filling the ventricles, but it does not play a significant role in the primary filling of the coronary arteries.