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blood is pumped from the right atrium to the right ventricle throught the tricuspid valve. similarly, on the other side of the heart, blood is pumped from the left atrium to the left ventricle thought the mitral valve. the purpose of these valves is to prevent blood flowing the wrong way. they ensure that blood always flows in the correct direction from the atriumto the ventricle.

similar valves called semilunar valves are present in the aorta and pulmonary artery at the point where they leave their respective ventricles. again their function is to prevent blood flowing backwards from the arteries into the heart. sometimes the heart valves are damaged by disease such as rheumatic fever of they may be defective at birth. any of these forms of valvular heart disease present a risk of a very serious complicationcalled infective endocarditis.

many systemic veins also have valves to ensure that blood will only flow towards the heart. sometimes they become defective and blood leaks back in the opposite direction, causing distension of the veins. these are called varicose veins.

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екатерина24131    2   12.11.2019 17:24    3