<Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> A heart valve normally allows blood to flow in only one direction through the heart . The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart . A heart valve opens or closes incumbent on differential blood pressure on each side . </P> <P> The four main valves in the heart are: </P> <Ul> <Li> The two atrioventricular (AV) valves, the mitral valve (bicuspid valve), and the tricuspid valve, which are between the upper chambers (atria) and the lower chambers (ventricles). </Li> <Li> The two semilunar (SL) valves, the aortic valve and the pulmonary valve, which are in the arteries leaving the heart . </Li> </Ul>

How does the action of the pulmonary semilunar valve differ from the atrioventricular valve