The pulmonary circulation starts with the right ventricle of the heart, from where the desoxgenized blood is pumped to the lung capillaries via the pulmonary artery, from where it then returns to the left atrium via the pulmonary vein, so that the systemic circulation can start again. The atria are separated from the ventricles by atrioventricular valves, the ventricles and their efferent vessel are separated by the aortic or pulmonary valve.
