Mitral valve prolapse is a condition which primarily affects the .

The sino-atrial node is the heart's electrical pacemaker tissue, not a valve, and is unrelated to mitral valve prolapse.

The mitral valve and the bicuspid valve are the same structure - a two-leaflet valve located between the left atrium and left ventricle. In mitral valve prolapse, one or both leaflets bulge (prolapse) back into the left atrium during ventricular systole, which can cause regurgitation and a characteristic clicking murmur.

The tricuspid valve is a three-leaflet valve on the right side of the heart separating the right atrium and right ventricle, a distinct structure from the mitral valve.

The descending aorta is a major systemic artery, not a cardiac valve, and is not involved in mitral valve prolapse.