as being sort of a sheet of these cells

也就是一片这样的细胞
that are all connected to each other.

都是紧紧地相互连接在一起
If I start an action potential in one space,

如果在某处发动一个动作电位
it's going to flow over the surface.

就会传遍整个心肌表面
As it flows over the surface cells will be contracting right behind it;

传遍心肌也就是意味着随即发生收缩
so electrical flow followed immediately by contraction locally.

因此电流所过之处随即就是局部收缩
Does that make sense?

明白了吗
You could imagine that this now--

你可以想象一下
because they're directly electrically coupled,

这是因为它们是直接耦合电联的
signals can pass very quickly over the surface of the heart.

信号可以迅速的传遍整个心脏表面
They can pass very quickly from one to another,

非常迅速的从一个细胞传至另一个细胞
so I just need to start an action potential in one place,

因此我只需要在某一处启动一个动作电位