I'm going to end with the final reading response.

我将以最后的阅读回复结束。

BUT! When you trace a single sympathetic signal, from the initial stimulus to the final response, those chemicals can be kind of hard to keep track of.

但是！当你追踪一个单一的交感信号，从最初的刺激到最终的反应，这些化学物质很难跟踪。