AEMCA Practice Exam

When do the coronary arteries receive blood?

1. Systole

2. Diastole

3. During contraction

4. During relaxation

The correct answer is: Diastole

The coronary arteries receive blood during diastole, which is the phase of the cardiac cycle when the heart muscle relaxes. During this relaxation phase, the pressure in the heart chambers decreases, allowing blood to flow from the aorta into the coronary arteries, supplying oxygen and nutrients to the heart itself. In contrast, during systole, when the heart muscle contracts to pump blood out of the ventricles, the pressure within the chamber is high. This contraction can partially occlude the coronary arteries due to the squeezing of the heart muscle, which limits blood flow. Therefore, the timing of coronary circulation is intricately linked to the heart's relaxation phase, making diastole the critical period for coronary artery perfusion. Understanding this helps underscore the importance of the heart's rhythm and function in maintaining its own blood supply for optimal health and performance.