Why is elastic recoil compliance) important to lung function? The kidneys aid in maintaining blood pressure by O preserving salt and water balance. maintaining a normal blood volume. a O producing renin. O All of the choices are correct. When the left ventricle contracts, the valve closes and the open. valve is pushed O bicuspid; pulmonary O tricuspid: pulmonary O tricuspid; aortic O mitral; aortic aortic; pulmonary