Which chambers of the heart fill with blood during the Q - T Interval?

During the Q-T interval of the cardiac cycle, the heart is primarily in a state of electrical activity, specifically reflecting the time taken for ventricular depolarization and repolarization. This interval starts at the beginning of the Q wave and ends at the end of the T wave on an electrocardiogram (ECG).

While the ventricles are completing their contraction during the Q-T interval, the atria are filling with blood from the systemic and pulmonary circulation. This filling occurs as the ventricular muscles contract and push blood out into the aorta and pulmonary arteries, leading to a decrease in pressure in the ventricles, allowing blood to flow from the atria into the ventricles. The right and left atria receive blood concurrently – the right atrium receives deoxygenated blood from the body through the superior and inferior vena cavae, while the left atrium receives oxygenated blood from the lungs via the pulmonary veins.

This makes it clear why the correct answer focuses on the right and left atrium; they fill with blood during this interval, preparing for the next cardiac cycle when they will contract to push blood into the ventricles. The involvement of both atria in this process is crucial for maintaining efficient circulation and heart function during the various