Which valve closes to prevent backflow into the left atrium when the left ventricle contracts?

Which valve closes to prevent backflow into the left atrium when the left ventricle contracts?

• A. Tricuspid Valve
• B. Aortic Valve
• C. Mitral (Bicuspid) Valve
• D. Pulmonary Valve

Answer: (C)

During left ventricular contraction, the pressure in the ventricle rises above that in the left atrium. The valve between the left atrium and left ventricle—the mitral valve—closes to prevent blood from flowing backward into the atrium. This closure is supported by the chordae tendineae and papillary muscles to keep the valve leaflets from flipping back into the atrium. Blood is then ejected into the aorta through the aortic valve, which opens during systole. The other valves—tricuspid between the right atrium and ventricle, and pulmonary between the right ventricle and pulmonary artery, along with the aortic valve's role in preventing backflow into the ventricle—serve their respective sides of the heart. If the mitral valve doesn’t close properly, backflow into the left atrium can occur during systole.

During left ventricular contraction, the pressure in the ventricle rises above that in the left atrium. The valve between the left atrium and left ventricle—the mitral valve—closes to prevent blood from flowing backward into the atrium. This closure is supported by the chordae tendineae and papillary muscles to keep the valve leaflets from flipping back into the atrium. Blood is then ejected into the aorta through the aortic valve, which opens during systole. The other valves—tricuspid between the right atrium and ventricle, and pulmonary between the right ventricle and pulmonary artery, along with the aortic valve's role in preventing backflow into the ventricle—serve their respective sides of the heart. If the mitral valve doesn’t close properly, backflow into the left atrium can occur during systole.