What is the pathway of blood through the pulmonary circuit starting from the right atrium?

The pathway of blood through the pulmonary circuit begins in the right atrium, where oxygen-poor blood enters. It then flows through the right atrioventricular (tricuspid) valve into the right ventricle. From the right ventricle, blood is pumped through the pulmonary semilunar valve into the pulmonary trunk, which divides into the left and right pulmonary arteries leading to the lungs. After gas exchange in the lungs, oxygen-rich blood returns to the left atrium via the pulmonary veins.