- LORD: left-oxygenated, right-deoxygenated - left: pulmonary vein -> left atrium -> left atrioventricular valve -> left ventricle -> aortic semi lunar valve -> aorta -> body - right: pulmonary artery -> right atrium -> right atrioventricular valve -> right ventricle -> pulmonary semi lunar valve -> pulmonary trunk/arteries -> lungs