来自《耶鲁大学开放课程：生物医学工程探索 第13集 第13集》

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  Blood pressure ranges between 120/80 mmHg.
  血压的范围是 120/80 毫米汞柱
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  We're going to see this in a few minutes
  马上我们就能看到
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  but those numbers represent the maximum pressure
  这个数字代表了心脏跳动产生的
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  and the minimum pressure during a heartbeat.
  最大压力和最小压力
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  The maximum pressure occurs
  当心脏有活性地收缩或跳动时
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  when the heart is actively contracting or beating.
  血压达到最大值
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  We'll talk about that more in a few minutes
  待会我们会再讲
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  and we'll talk about that in great detail on Thursday.
  下周四我们会详细讨论这个问题
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  Then it drops when the heart is relaxing.
  心脏舒张时血压降低
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  Blood pressure is generated in a cyclic fashion
  血压的产生是循环式的
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  because of beating of the heart,
  因为心脏的跳动是在不断重复
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  contract, relax, contract, relax,
  收缩 舒张 收缩 舒张