Sometimes second messengers collect signals from a variety of different receptor systems, translate them into one kind of internal change, and the cell then just has to know about that one thing changing.

第二信使分子能够收集,来自不同受体系统的信号,将它们转化为同一种细胞内在的变化,这样细胞就只需对一种变化作出反应

耶鲁公开课 - 生物医学工程探索课程节选

What happened in that case is he has learned that the raising of a hand is a signal that he is about to be hit and so he responds to that signal.

在这个例子中，他知道,举起的手臂是他即将挨打的信号,因此他对这个信号作出了反应。

耶鲁公开课 - 心理学导论课程节选