That is, the pressure in the left atrium is greater, becomes greater than the pressure in the right atrium. And this causes the septum premium to push against the septum sequandum which closes the forayman O'Valley. And this usually takes place within minutes following birth. Now, this ultimately causes all that blood to be redirected from the right atrium into the right ventricle and eventually into the pulmonary section and then into the lungs. And so we have the closure of that wall, the closure of that one way door that exists within that developing fetus. And this is what we call the Foraymon O Valley, or the closure of the Foraymon ovaly.