Oregon Certified Nursing Assistant State Practice Exam

During the resting phase/diastole of the heart, what occurs?

1. Ventricles pump blood through the blood vessels

2. The heart begins beating rapidly until the next contraction

3. The chambers fill with blood

4. Circulation stops

The correct answer is: The chambers fill with blood

During the diastole phase of the heart cycle, the chambers of the heart, specifically the atria and ventricles, are in a relaxed state, allowing them to fill with blood. This is the period when the heart is not actively contracting, which is crucial for ensuring that there is enough blood volume in the chambers before the next contraction occurs. When the heart muscle relaxes, the pressure within the chambers decreases, enabling blood from the veins (specifically the superior and inferior vena cavae into the right atrium and the pulmonary veins into the left atrium) to flow into the atria first and then into the ventricles before the next systole, or contraction phase. This filling phase is vital for maintaining effective circulation and ensuring that adequate blood is pumped out to the body with each heartbeat. The other options describe processes that do not accurately represent what happens during diastole. For example, pumping of blood occurs during systole, chambers getting filled with blood is a key characteristic of diastole, and circulation does not stop during this resting phase. Instead, it continues as blood flows back to the heart.