Blood Flow through the Heart/Lungs

Second Step

Blood passes from the right atrium to the right ventricle.

Third Step

Blood passes through the pulmonary artery to the lungs, where it is reoxygenated.

First Step

Blood returning from all parts of the body (except the lungs) enters the right atrium via the vena cava.

Fourth Step

Blood returns to the left atrium via the pulmonary vein, and passes through the ventricle to the aorta.

Fifth Step

The aorta pumps out blood to the rest of the body.