Valve States During Ventricular Systole

Steps:

• Identify valve X as tricuspid (atrioventricular) and Y as pulmonary (semilunar) based on right heart diagram.
• Recall that ventricular relaxation fills ventricle via open AV valve and closed semilunar valve.
• During contraction (systole), pressure rises in ventricle, closing AV valve to block atrial backflow.
• Simultaneously, high pressure opens semilunar valve for blood ejection to lungs.

Why B is correct:

• In cardiac systole, the atrioventricular valve closes while the semilunar valve opens, per the heart's one-way flow mechanism to prevent regurgitation and ensure pulmonary circulation.

Why the others are wrong:

• A: Both closed blocks outflow, halting circulation.
• C: Both open allows backflow to atrium, disrupting pressure gradients.
• D: AV open permits regurgitation; semilunar closed prevents ejection.

Final answer: B