500
the flow of blood through the heart and body starting and ending with the vena cava
What is veins to vena cava, into Rt atrium, through tricuspid valve into Rt ventricle; through pulmonary valve into pulmonary artery to the lungs; then from lungs via pulmonary vein into Lt atrium, through bicuspid/mitral valve into Lt ventricle, through aortic valve into aorta through arteries, to arterioles, then capillaries to venules, veins and back to heart by vena cava