Which valves prevent backflow from the ventricles into the atria during ventricular contraction?

Which valves prevent backflow from the ventricles into the atria during ventricular contraction?

• A. Atrioventricular valves.
• B. Semilunar valves.
• C. Pulmonary valves.
• D. Mitral valves.

Answer: (A)

During ventricular contraction, pressure in the ventricles rises and the valves between the atria and ventricles close to keep blood from flowing backward into the atria. These are the atrioventricular valves, which include the mitral valve on the left and the tricuspid valve on the right. Their closure ensures that blood is pushed forward into the aorta and pulmonary artery through the semilunar valves. The semilunar valves themselves govern flow from the ventricles to the great arteries and prevent backflow into the ventricles, but they do not prevent backflow into the atria.

During ventricular contraction, pressure in the ventricles rises and the valves between the atria and ventricles close to keep blood from flowing backward into the atria. These are the atrioventricular valves, which include the mitral valve on the left and the tricuspid valve on the right. Their closure ensures that blood is pushed forward into the aorta and pulmonary artery through the semilunar valves. The semilunar valves themselves govern flow from the ventricles to the great arteries and prevent backflow into the ventricles, but they do not prevent backflow into the atria.