What prevents backflow into the atria?

What prevents backflow into the atria?

• A. Semilunar valves
• B. Atrioventricular valves
• C. Both AV and semilunar valves
• D. None of the above

Answer: (B)

One-way flow in the heart is driven by valves that close to block reverse movement. To stop blood from leaking back into the atria when the ventricles contract, the atrioventricular valves—the mitral and tricuspid valves—shut. Their cusps come together, aided by chordae tendineae anchored to papillary muscles, preventing them from bulging back into the atria during ventricular systole. Semilunar valves, on the other hand, prevent blood from flowing back from the aorta and pulmonary artery into the ventricles, not into the atria. So the structure that prevents backflow into the atria is the atrioventricular valves.

One-way flow in the heart is driven by valves that close to block reverse movement. To stop blood from leaking back into the atria when the ventricles contract, the atrioventricular valves—the mitral and tricuspid valves—shut. Their cusps come together, aided by chordae tendineae anchored to papillary muscles, preventing them from bulging back into the atria during ventricular systole. Semilunar valves, on the other hand, prevent blood from flowing back from the aorta and pulmonary artery into the ventricles, not into the atria. So the structure that prevents backflow into the atria is the atrioventricular valves.