NEUR3101 Study Guide - Final Guide: Voltage Clamp, Nernst Equation, Reversal Potential
Document Summary
Understand the importance of conductance" and know how to calculate it using ohm"s law for neurophysiologists" Neurons - like about them in terms of electrical circuits. I = 1/r x v or i = g v. G is conductance a/v measured in siemens s, also called mho. Conductance = ease of passage of current ("permeability") Ohm"s law says: for a fixed v" (potential), bigger g" means bigger i". I =ina or ik = membrane current carried by a type of ion. G = gna or gk = membrane conductance of that ion. V = electrical potential experienced by that ion. An ion experiences 0 electrical potential at nernst potential, so: Modified ohm"s law (for neurophysiologists): im = g (vm - eion) Im = membrane current carried by the permeant ion. Eion = nernst potential for the permeant ion. When vm = eion, the equation tells us im = 0 for the permeant ion.
