Through which valve does blood exit the left atrium?

Through which valve does blood exit the left atrium?

• A. Left AV (Bicuspid/Mitral) valve
• B. Right AV valve
• C. Aortic valve
• D. Pulmonary valve

Answer: (A)

Blood returning from the lungs enters the left atrium and then exits into the left ventricle through the left atrioventricular valve, also known as the mitral valve. This valve sits between the left atrium and left ventricle and opens to allow flow during ventricular filling, then closes to prevent blood from flowing back into the atrium when the ventricle contracts. The other valves are located elsewhere: the right AV valve sits between the right atrium and right ventricle, the aortic valve sits at the exit of the left ventricle to the aorta, and the pulmonary valve sits at the exit of the right ventricle to the pulmonary artery.

Blood returning from the lungs enters the left atrium and then exits into the left ventricle through the left atrioventricular valve, also known as the mitral valve. This valve sits between the left atrium and left ventricle and opens to allow flow during ventricular filling, then closes to prevent blood from flowing back into the atrium when the ventricle contracts. The other valves are located elsewhere: the right AV valve sits between the right atrium and right ventricle, the aortic valve sits at the exit of the left ventricle to the aorta, and the pulmonary valve sits at the exit of the right ventricle to the pulmonary artery.