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The semilunar valves (the pulmonary and aortic valves) are formed from four thickenings at the cardiac end of the truncus arteriosus. [9] These thickenings are called endocardial cushions . [ citation needed ] The truncus arteriosus is originally a single outflow tract from the embryonic heart that will later split to become the ascending aorta ...
A Wiggers diagram modified from [1]. A Wiggers diagram, named after its developer, Carl Wiggers, is a unique diagram that has been used in teaching cardiac physiology for more than a century.
The heart is a muscular organ situated in the mediastinum.It consists of four chambers, four valves, two main arteries (the coronary arteries), and the conduction system. The left and right sides of the heart have different functions: the right side receives de-oxygenated blood through the superior and inferior venae cavae and pumps blood to the lungs through the pulmonary artery, and the left ...
The anchored and electrically inert collagen framework of the four valves allows normal anatomy to house the atrioventricular node (AV node) in its center. The AV node is the only electrical conduit from the atria to the ventricles through the cardiac skeleton, which is why atrial fibrillation can never degrade into ventricular fibrillation.
The aortic and pulmonary valves known as the semilunar valves open, and a defined fraction of blood within the heart is ejected into the aorta and pulmonary trunk. Ejection of blood from the heart is known as systole. Ejection causes pressure within the ventricles to fall, and, simultaneously, the atria begin to refill (atrial diastole).
The valve of the coronary sinus is a thin, semilunar (half-moon-shaped) valve located on the anteroinferior part of the opening into the right atrium. [5] It is formed by a semicircular fold of the lining membrane of the right atrium. It is situated at the base of the inferior vena cava. [citation needed]
Regurgitation in or near the heart is often caused by valvular insufficiency (insufficient function, with incomplete closure, of the heart valves); for example, aortic valve insufficiency causes regurgitation through that valve, called aortic regurgitation, and the terms aortic insufficiency and aortic regurgitation are so closely linked as ...
There is another system of semilunar valves that prevents back-flow of lymph along the lumen of the vessel. [4] Lymph capillaries have many interconnections (anastomoses) between them and form a very fine network. [6] Rhythmic contraction of the vessel walls through movements may also help draw fluid into the smallest lymphatic vessels ...