cells after traveling back to the heart, then, through the pulmonary circulation, and, finally, back through the arteries and capillaries of the systemic circulation. From the capillaries, blood in the systemic circulation begins its return to the heart through the small venules, then, through the larger veins, and, finally, through the two largest veins, the superior vena cava, which drains the head, neck, and arms, and the inferior vena cava, which drains the rest of the body. These two veins empty into the right atrium of the heart.
