阀【名词】1.【机械工程】阀，活门，舌门；汽门; 2.【解剖学；动物学】瓣，瓣膜；(贝)壳瓣；【植物；植物学】荚片；(藻的)瓣；(果实的)裂片; 3.【建筑】门的一扇; 4.【无线电】电子管，真空管
a membranous fold in a canal or passage that prevents backward flow of material passing through it. aortic valve a semilunar valve that separates the left ventricle and the aorta; it opens with end diastole, causing the second heart sound. atrioventricular v's the cardiac valves between the right atrium and right ventricle (tricuspid valve) and the left atrium and left ventricle (mitral valve). bicuspid valve mitral valve. bicuspid aortic valve a congenital anomaly of the aortic valve, caused by incomplete separation of two of the three cusps; it is generally asymptomatic early in life but is predisposed to calcification and stenosis later on.