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.
Most often the threshold potential is a membrane potential value between â40 and â55 mV, but it can vary based upon several factors. A neuron's resting membrane potential (â70 mV) can be altered to either increase or decrease likelihood of reaching threshold via sodium and potassium ions.hreshold tracking allows for the strength of a test stimulus to be adjusted by a computer in order to activate a defined fraction of the maximal nerve or muscle potential.