来自《耶鲁大学开放课程：生物医学工程探索 第25集 第25集》
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The normal valve opens like a doorway,正常瓣膜的开合就像门板 -
so the part that's shut totally opens.关闭的部分会完全打开 -
There's a very clear path for flow.形成非常通畅的血流通路 -
In this kind of a ball valve, the ball is still in the way.这种球形瓣膜 球还是位于血流通路上 -
The fluid has to go around血流必须绕过这个球 -
the ball in order to eject into the aorta,从而射入主动脉 -
for example, if this was an aortic valve.如果这是个主动脉瓣的话 -
Because it has to go around it,因为血流必须绕过它 -
there's an obstacle to这种阻碍血流的障碍物 -
blood flow creates an additional resistance.就产生了额外的血流阻力 -
Your heart has to work harder而绕过这个位于中心的巨大球体 -
in order to overcome the resistance of the flow所产生的额外血流阻力