PHGY 311 Lecture Notes - Lecture 3: Reversal Potential, Nernst Equation, Potential Gradient
7 Oct 2018
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Document Summary
Nerve cells are polarized more negative inside than the surrounding environment. Major ions: ca++, na+, k+ and cl- contribute the most to the signal. Concentration gradients that makes the ions want to move across the cell, as they move, an electrical potential gradient across the membrane. The potential at which the concentration gradient is balanced out is given by the nernst equation and is called the equilibrium. For each ion, there is a different equilibrium constant. At resting potential, none of the ions are at equilibrium so there is force that drives the movement of these ions across the membrane. This driving force depends on the difference between the membrane potential and he equilibrium constant. Flow of ion is governed by the pathway (conductance) and the driving force. Driving force pushing na+ in, k+ out, ca++ in and cl- out. Each of these forces has a magnitude (given by g*(vm e)) and a direction.
