PHGY 313 Lecture Notes - Resting Potential, Generalised Epilepsy, Alpha Helix
8 Feb 2013
School
Department
Course
Professor
Document Summary
Depolarization of the cell during the action potential is caused by the influx of sodium ions across the membrane, and repolarization is caused by the efflux of potassium ions. Membrane currents and conductances: see fig. Opening the potassium channels only causes the potassium ions to flow out of the cell, down their concentration gradient, until the inside becomes negatively charged and vm = ek. The driving force on k+ is defined as the difference between the real membrane potential and the equilibrium potential, and it can be written as vm - ek. The membrane potential is so negative with respect to the sodium equilibrium potential and there is a driving force on na+ However there can be no net movement of sodium ions as long as the membrane is impermeable to na: when the channels are open, however,: The ionic permeability of the membrane, gna is high and there is a large driving force pushing on na+.
