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.
Receptor potential is the same as resting membrane potential. For an impulse to take place there must be a state of readiness in the neuron, so the resting membrane potential is an electrical charge brought about by the difference between positive and negative ions outside and inside the cell, if the ions were distributed equally inside and outside there would be no charge and no potential.