ocr: 90 +20 mv. mv. In the resting state, the outside of a cardiac muscle cell has a positive - - electrical charge as compared to the t++ inside (as measured using an intracel- ular lectrode). With depolarization, +t this situation is rversed. "Resting" Depolarized cell cell E When external electrodes are used, only the surface voltages are neasured. @ - - - - - - and Such resting voltages, areas, between may be depolarized visualized as electrical dipoles and their Depolarized "Resting" tudes and directions treated as magni vectors.