CO2 in from tissue,
through capillary bed to venues through valve,
CO2 in to SVC,
through heart out artery to lung,
Co2 out from pulmonary artery,
CO2 out from lung,
O2 in to lung,
O2 in pulmonary veins,
O2 out from aorta,
through arteries-arterioles,
O2 out from tissue