Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

During which phase of heart function does the right atrium fill with blood?

1. Systole

2. Diastole

3. Isovolumetric contraction

4. Cardiac output

The correct answer is: Diastole

The right atrium fills with blood during diastole, which is the phase of the cardiac cycle when the heart muscle relaxes after contraction. During this relaxation phase, the pressure in the heart decreases, allowing the atria to fill with blood returning from the body through the superior and inferior vena cavae. This influx of blood into the right atrium continues throughout diastole until the heart prepares for contraction again. In contrast, systole refers to the phase when the heart contracts, pumping blood out of the atria and into the ventricles and subsequently out of the heart. Isovolumetric contraction is a specific phase within systole where the ventricles contract but all heart valves are closed, resulting in no blood movement. Cardiac output encompasses the amount of blood the heart pumps in a given time and is influenced by the phases of the cardiac cycle but does not specifically refer to the filling phase of the atria.