deoxygenated blood enters the heart through the ____ and into the ___ of the heart. then it passes through the ___ valve to the __ and flows out of the heart through the ___ valve and then the __ to the __.

oxygenated blood returns to the heart through the ___ and enters the __ of the heart. from there, the blood passes through the ___ valve into the ___. then it passes through the ___ valve to the ___ where the blood can be distributed to tissues of the ___.