Anatomy of the blood circulation
The oxygen-poor blood is conducted from all parts of the body through the veins to the heart. All venous blood finally flows through the upper and lower vena cava into the right atrium and from there into the right ventricle, also called the right ventricle. The right atrium and right ventricle together form the so-called right heart.
From the right heart, the blood, which is still low in oxygen, is pumped to the lungs to enrich it with oxygen (so-called pulmonary circulation). The oxygen-enriched blood now flows into the left heart (first into the left atrium, then into the left ventricle), and is then pumped from the left ventricle through the arteries back to the various parts of the body. In doing so, the heart always pumps the amount of blood volume required by the body per unit of time into the body (so-called cardiac output or cardiac output per minute).