Mitral Valve Function
The heart is a muscular structure with four chambers including two atria, which are the filling chambers and two ventricles, which are the pumping chambers. The venous blood is drained from the body to the right chambers of the heart, then oxygenated in the lungs and ejected to the entire body by the left chambers of the heart.
The human heart has four valves (flaps made of tissue) that control the direction of blood flow in the circulation. Normal valves act like a system of one-way doors, which assures unidirectional blood flow through the various chambers of the heart. The aortic and mitral valves are part of the "left" heart and control the flow of oxygen-rich blood from the lungs to the body, while the pulmonic and tricuspid valves are part of the "right" heart and control the flow of oxygen-depleted blood from the body to the lungs.
The aortic valve lies between the left ventricular changer and aorta, preventing blood from leaking back into the left ventricle after it has been ejected into the circulation. The mitral valve lies between the left atrium and left ventricle preventing blood from leaking back into the left atrium during ejection (systole). Similarly on the right side, the pulmonic valve separates the right ventricle from the pulmonary artery, whereas the tricuspid valve separates the right ventricle from the right atrium.
The normal mitral valve opens when the left ventricle relaxes (diastole) allowing blood from the left atrium to fill the decompressed left ventricle. When the left ventricle contracts (systole), the increase in pressure within the ventricle causes the valve to close, preventing blood from leaking into the left atrium and assuring that all of the blood leaving the left ventricle (the stroke volume) is ejected through the aortic valve into the aorta and to the body. Proper function of the valve is dependent on a complex interplay between the annulus, leaflets and subvalvular apparatus.