ABSTRACT
At the microscopic level, all tissues are composed of cells and extracellular fluids. The cell has two distinct parts: the outer, insulating membrane and the inner cytoplasm and nucleus which, such as the extracellular fluid, has high conductivity. Because of the membrane, the cell appears to be an insulator. Accordingly, almost all the current induced in tissues by low-frequency electric field flows around the cells. The insulating membrane, which completely surrounds the conducting core, makes the cell itself a series combination of the membrane capacitance and the cytoplasmic resistance.
