Definition: A portion of a line which starts at a point and goes off in a particular direction to infinity. Try this Adjust the ray below by dragging an orange dot and see how the ray AB behaves. Point A is the ray's endpoint.
Plant cell cross-section, showing the membrane. Animal cell cross-section, showing the membrane. Resting membrane potential is the difference in voltage of the fluids inside a cell and outside a cell, which is usually between -70 to -80 millivolts (mV). View slideshow of images above.
1 the resting membrane potential of a cell is determined by the net flow of ions through the leak channels that are open in the resting state.2  the exact proportions and nature of the ion channels varies from cell to cell, and therefore, so does the RMP. the resting membrane potential of a cell is determined by the net flow of ions through the leak channels that are open in the resting state.