Flow becomes more turbulent as velocity increases and the diameter of the column becomes smaller. It states this likelihood is related to fluid viscosity, density, velocity, and the diameter of the column through which the fluid is traveling. Reynold’s number can quantify the likelihood of a fluid demonstrating turbulent flow. In contrast, turbulent flow is rough with high resistance and has a chaotic, unorganized structural pattern. It is conceptualized as layers neatly stacked in parallel as they flow through a column. Laminar flow is smooth with low resistance. The atria fill with blood then contract, causing the atrioventricular valves to open so the ventricles can fill with blood. Tension on the chordae tendineae also decreases. The sinus-like leaflets will begin to fill with blood, which will distend the valve cusp toward one another for closure.

As the ventricle stops contracting and pressures fall in diastole, elastic recoil of the great arteries will cause blood to fall back toward the heart. The rise in pressure pushes the aortic and pulmonic valves open, allowing blood to flow forward. During systole, the tension provided by the chordae tendineae keep the atrioventricular valve leaflets together. The heart valves permit forward flow of blood while preventing backward regurgitant flow.

Endothelial cells accomplish this via communication with myofibroblast and smooth muscle cells in the subendocardial layer. They modulate the elastic modulus of the valve, which is the valve’s strain for a given amount of stress. Research has shown these cells are very functionally active and can alter the mechanical properties of the aortic valve, which in turn alters its function. The endothelial cells of the valves are genotypically and phenotypically unique from other endothelial cells found in the body. The connective tissue of the subendocardium is continuous with the connective tissue of the myocardial layer. It contains fibroblasts, myofibroblasts, smooth muscle cells, nerves, elastic and collagenous fibers. The subendocardium contains a vast population of cells types. Ī single layer of endothelial cells called the endocardium lines the surface of the heart valves. The aortic valve on average opens and closes 100000 times a day. The superior aspects of the right and left aortic valve leaflets contain the origins of the coronary arteries. The pulmonic valve separates the right ventricle from the pulmonary artery, and the aortic valve separates the left ventricle from the aorta. These valves are composed of three sinus-like leaflets also attached to a valve annulus. The semilunar valves separate the ventricles from the great arteries. The tricuspid valve consists of three leaflets, while the mitral valve consists of two leaflets. The tricuspid valve separates the right atrium from the right ventricle, and the mitral valve separates the left atrium from the left ventricle. The leaflets also attach to a fibrous ring, known as the valve annulus, that supports the valve between the atria and ventricles. These valves are composed of leaflets attached to papillary muscles in the ventricle via thin cord-like structures called chordae tendineae. The atrioventricular valves are located on the floor of the atria and empty into the ventricles. There are four chambers of the heart: the right atrium, the right ventricle, the left atrium, and the left ventricle.

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