During atrial diastole, which valves open to permit ventricular filling?

During atrial diastole, which valves open to permit ventricular filling?

• A. Aortic and Pulmonic
• B. Tricuspid and Mitral
• C. Pulmonic and Tricuspid
• D. Aortic and Mitral

Answer: (B)

During atrial diastole, the ventricles are filling, so the valves that open to let blood flow from the atria into the ventricles are the atrioventricular valves: the mitral valve on the left and the tricuspid valve on the right. As the ventricles relax, their pressure falls below the atrial pressure, causing these valves to open and blood to passively fill the ventricles. The semilunar valves (aortic and pulmonic) stay closed during this phase to prevent backflow into the ventricles.