When the left atrium contracts, blood is pushed through which valve into the left ventricle?

When the left atrium contracts, it facilitates the flow of oxygen-rich blood into the left ventricle through the mitral valve, also known as the bicuspid valve. This valve is specifically designed to allow blood to flow in one direction—from the left atrium to the left ventricle—while preventing any backflow into the atrium when the ventricle contracts. The structure of the mitral valve, with its two leaflets, ensures that it opens sufficiently during atrial contraction and closes tightly during ventricular contraction, thereby maintaining proper circulation within the heart.

In contrast, the other options refer to different valves within the heart's circulation. The pulmonary valve is located between the right ventricle and the pulmonary artery, while the aortic valve is situated between the left ventricle and the aorta. Finally, the tricuspid valve is found between the right atrium and right ventricle. Each of these valves serves a distinct role in governing the flow of blood through their respective pathways, making them unrelated to the movement of blood from the left atrium to the left ventricle.