During the ventricular ejection phase, which valves are open?

During the ventricular ejection phase, which valves are open?

• A. Semilunar valves open; AV valves closed
• B. AV valves open; semilunar valves closed
• C. Both sets open
• D. Both sets closed

Answer: (A)

During ventricular ejection, the ventricles are in systole and their pressure rises above the pressures in the pulmonary artery and aorta. This pressure difference opens the semilunar valves, allowing blood to be ejected into the pulmonary trunk and aorta. Simultaneously, the higher ventricular pressure pushes the AV valve cusps closed (aided by the chordae tendineae), preventing backflow into the atria. If the AV valves stayed open, blood would regurgitate into the atria; if the semilunar valves stayed closed, ejection would not occur. So, semilunar valves are open and AV valves are closed during ventricular ejection.

During ventricular ejection, the ventricles are in systole and their pressure rises above the pressures in the pulmonary artery and aorta. This pressure difference opens the semilunar valves, allowing blood to be ejected into the pulmonary trunk and aorta. Simultaneously, the higher ventricular pressure pushes the AV valve cusps closed (aided by the chordae tendineae), preventing backflow into the atria. If the AV valves stayed open, blood would regurgitate into the atria; if the semilunar valves stayed closed, ejection would not occur. So, semilunar valves are open and AV valves are closed during ventricular ejection.