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.
It is -70 millivolts. The resting potential of a neuron refers to the voltage difference across the plasma membrane of the cell, and is expressed as the voltage inside the memâ¦brane relative to the voltage outside the membrane.