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.
Resting membrane potential is: 1  the unequal distribution of ions on the both sides of the cell membrane; 2  the voltage difference of quiescent cells; 3  the membrane potential that would be maintained if there werenât any stimuli or conducting impulses across it;  determined by the concentrations of ions on both sides of the membrane;