And so the resistance as a result of that decreases. Now, because we decrease the resistance and the pressure in the lungs, what happens is now the blood from the right atrium is more likely to move into the right ventricle and into the pulmonary trunk and then into the lungs, where the pressure is now is now low. So air fills the alveoli of the lungs, expanding them. This decrease in the resistance and the pressure in the lungs. And as a result, the blood rushes from the right side of the heart and into the lungs. Now, as the blood moves along this side of the heart more easily the pressure inside the right atrium and the right ventricle decreases.