A. The tricuspid valve ensures blood flows from the left atrium to the left ventricle, preventing backflow into the pulmonary veins

B. The mitral valve regulates blood flow from the right atrium to the right ventricle, ensuring blood does not reflux into the vena cava during ventricular contraction

C. The pulmonary valve prevents blood from flowing back into the right ventricle when it has been pumped into the pulmonary arteries

D. The aortic valve allows oxygenated blood to flow from the left ventricle directly into the lungs for oxygenation