from the smaller veins in the head, upper chest, and arms is collected by the anterior vena cava
. The posterior vena cava
collects the blood from the posterior
parts of the body. Then both the anterior vena cava and the posterior vena cava empty into the right atrium
The oxygen-poor blood that the right atrium receives passes through the tricuspid valve into the right ventricle. The right ventricle pumps the blood through the pulmonary semilunar valve and into the pulmonary artery, which is the large vessel that loops from the bottom of the right ventricle over the top of the heart.
Then the pulmonary artery carries the blood to the lungs where it is oxygenated and sent through the pulmonary veins into the left atrium of the heart. The left atrium delivers the oxygen-rich blood through the bicuspid valve and into the left ventricle. From the left ventricle, the oxygenated blood goes through the aortic semilunar valve into the aorta. The aorta distributes the blood to other arteries, which in turn distribute it to the other parts of your body.
Without all the added explanation...
Anterior and posterior vena cava -> right atrium -> tricuspid valve -> right ventricle -> pulmonary semilunar valve -> pulmonary artery -> lungs -> pulmonary veins -> left atrium -> bicuspid valve -> left ventricle -> aortic semilunar valve -> aorta -> arteries -> body.