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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that are inside our circulatory system so they must be--压强的大小 这个压强必须 -
but they're only a fraction of 1 atm, how can that be?这不到一大气压 怎么会这样 -
An atm is 760 mmHg,一个大气压是七百六十毫米汞柱 -
that's the pressure in this room.屋里的压力就这么大 -
If your blood pressure is 120/80 what does that mean?如果你的血压是120/80的话会怎样 -
Well, pressure is--we only care about differences in pressure.压强是 我们只关注压差 -
It's relative pressure that matters not the absolute pressure.相对压力更有意义 而不是绝对压力 -
When you say your blood pressure is 120/80 that means说血压为 120/80 的意思是 -
120 mmHg above Atmospheric;比大气压高一百二十毫米汞柱 -
80 mmHg above Atmospheric.比大气压高八十毫米汞柱 -
Otherwise our blood vessels would collapse否则我们的血管会塌陷的 -
because we're surrounded by air that's 760 mmHg,因为周围的空气压力是七百六十毫米汞柱