or a garden hose that was hooked up to a reservoir and a balloon on one end,

一端连接在蓄水池或者气球上的水管
and you inflated it, and deflated it,

你使其膨胀再收缩
inflated it, and deflated it,

再膨胀再收缩
you'd be pushing water out and pulling

你就会把水推出去再吸回来
it in and it would go back and forth in this way.

就会像这样来回运动
If you're increasing and decreasing the volume by the same amount

如果体积增加和减少的量相等
you'd be pushing out a volume of water and pulling it back in.

你得推出一定量的水也吸回同样的水
Now that's a kind of a flow but it's not the continuous

这就形成了体流动
one directional kind of flow that we have in our circulatory systems.

但并不像循环系统内单向的连续流动
That would be a--you could

那将会是你们可以
imagine a circulatory system that's based on that,

想象以此为基础的一个循环系统
where you have a heart that

其中心脏把血液