Opteonâ¢ YF (HFO-1234yf) is a low global warming potential (GWP) refrigerant for use in automotive air-conditioning systems. Opteonâ¢ YF (HFO-1234yf) has a chemical structure of CF3CF= CH2 2,3,3,3-tetrafluoropropene.
During isovolumetric relaxation, which is the second last phase of the cardiac cycle, all the heart valves are closed. This means that there is no blood passing between the cardiac chambers or out of the heart. The pressure drop below 120 mmHg as the ventricles relax causes the semilunar valves to close. As the pressure drops further, the atrial pressure exceeds that of the ventricles and the atrioventricular valves open. Meanwhile, blood is being pumped around the body.
The semilunar valves (SV) are two valve structures that sit between the right ventricle and the pulmonary artery and between the left ventricle and the aorta. The flaps of the valves open and close to allow the unidirectional flow of blood out of the heart, while preventing backflow of blood.The valve between the left ventricle and aorta is called the aortic valve and the valve between the pulmonary artery and right ventricle is called the pulmonary valve.The heart has two types of valves: the atrioventricular (AV) and semilunar.he semilunar valves open to let blood pass out of the ventricles. The right ventricle pumps into the pulmonary artery, which leads to the lungs, and the left ventricle empties into the aorta, a main artery that distributes oxygen rich blood to the rest of the body.