Remember that at rest, cells are negatively charged relative to the slightly positive outside environment and when they depolarize, the cells become positively charged, leaving a slightly negative charge in the outside environment.

要记住在静息状态下，细胞带负电，其外部环境则相对稍带正电；当它们去极化时，细胞带有正电，它的外部环境带有负电。