What is the mitral valve?
The mitral valve is one of the four heart valves. It is located between the left atrium and the left ventricle. The tricuspid valve is designed to ensure that blood does not flow backwards on its way towards the heart as well as ensure the proper exchange of oxygen and carbon dioxide levels within the lungs to the entire body’s advantage.
The heart is an organ that is divided into several parts, which help perform its main function: to carry oxygen-rich blood to the rest of the body (cells, tissues and organs) in order to feed them, and receive carbon dioxide enriched blood to be sent to the lungs, where the oxygen exchange takes place.
The heart valves are small structures that are responsible for preventing blood from flowing backwards by ensuring they steer in one direction towards the heart. The mitral valve is an atrioventricular valve that consists of two membranes (cusps), which are very resistant and formed from connective tissue that open and close with each beat in a coordinated manner. The flaps are connected to a valvular ring, through which they are connected to the wall of the heart. The edges of the membranes are joined to the papillary muscles by tendinous cords, strands of connective tissue that are triggered by blood flow and cardiac phases that help prevent blood from returning backwards.
What function does the mitral valve serve?
The heart is a pump that is known to carry oxygen-rich blood from the lungs to the cells of tissues and organs, in exchange for carbon dioxide enriched blood that needs to be transformed. The oxygenated blood travels towards organs and tissues in the body through the aorta, the artery that carries nourishment to the whole body and further splits into smaller and smaller branches and capillaries. Carbon dioxide enriched blood returns to the heart through the veins, which transform it to oxygen.
The mitral valve oversees the passage of oxygenated blood through the orifice located between the left atrium and left ventricle.
The cardiac cycle consists of two phases: a relaxation phase (the diastole) and a contraction phase (the systole). During the first stage (the diastole phase), the valves between the atria and ventricles are open, and the whole heart is relaxed. At this stage, the semilunar valves are closed, preventing blood from entering the vascular beds. During the second stage (the systole phase), the atria and ventricles contract in a coordinated manner: first the atria (atrial systole) and then the ventricles (systole). During ventricular contraction, blood that is present in the atria reaches the ventricles and then the atrioventricular valves are closed. The contraction of the left ventricle pumps blood into the aorta for the blood to be distributed to all areas of the body.
The mechanism of the atrio-ventricular valves and the mitral valve is adjusted by blood flow and by pressure exerted in the phases of the cardiac cycle. During the ventricular systole, blood pressure is exerted upwards against the membrane, preventing blood from flowing backwards. The chordae tendineae (heart strings) which connect the papillary muscles to the tricuspid valve and the mitral valve in the heart, prevent the valve from being pushed upwards inside the atrium. In cases regarding functional or anatomical defects, this can lead to problems such as valve prolapse.
