During which phase are the AV valves open and the heart is relaxed?

During which phase are the AV valves open and the heart is relaxed?

• A. Diastole
• B. Atrial Systole
• C. Isovolumetric Contraction
• D. Ejection

Answer: (A)

Diastole is the phase when the heart muscle is relaxed. In this state, ventricular pressure drops below atrial pressure, causing the mitral and tricuspid (AV) valves to open. Open AV valves let blood flow passively from the atria into the ventricles, which is how the ventricles fill. The heart remains relaxed during this filling period, with atrial contraction (near the end of diastole) helping top off the ventricles. In the other phases, the ventricles contract or valve status changes (AV valves close to prevent backflow), so the AV valves aren’t open while the heart is actively contracting.

Diastole is the phase when the heart muscle is relaxed. In this state, ventricular pressure drops below atrial pressure, causing the mitral and tricuspid (AV) valves to open. Open AV valves let blood flow passively from the atria into the ventricles, which is how the ventricles fill. The heart remains relaxed during this filling period, with atrial contraction (near the end of diastole) helping top off the ventricles. In the other phases, the ventricles contract or valve status changes (AV valves close to prevent backflow), so the AV valves aren’t open while the heart is actively contracting.