The purpose of heart valves is to ensure blood flow continues in one direction. The heart has two types of valves. Atrioventricular valves are located between the atria and ventricles. Semilunar valves, so-called because they are shaped like a half-moon, are found between the left ventricle and aorta and the right ventricle and the pulmonary artery, according to About.com.
HowStuffWorks.com says there are four valves in the human heart. The tricuspid valve closes the right atrium. The pulmonary valve stops blood flow back into the right ventricle. The location of the mitral valve is at the exit of the left atrium. The aortic valve closes the left ventricle.
WebMD describes these valves as flaps, which open to allow blood flow as it progresses through the chambers of the heart. All the valves have three flaps, with the exception of the mitral valve, which has only two. Any of these four valves has the potential of leaks. When valves leak, some blood flows in the wrong direction through a process doctors call valve regurgitation. Sometimes such leaks cause few problems and go unnoticed. At other times they lead to minor or serious health problems, depending on the interference with blood flow through the individual's heart. Doctors treat leaky heart valves using medication, surgical repair and surgical replacement of the valve.