Cell Membrane Dynamics: Ion Transport and Electric Fields

This lecture discusses the dynamics of ion transport across cell membranes, focusing on the behavior of potassium and sodium ions. It begins with the initial conditions of an oocyte, where all ion channels are closed, leading to constant concentrations and no net charge. The instructor explains how opening potassium channels allows for diffusion, creating a net positive charge outside the cell and establishing an electric field. The lecture then addresses the resulting currents and the mathematical modeling of these processes, including Poisson and continuity equations. The discussion progresses to the sudden opening of sodium channels, highlighting the changes in ion concentrations and the resulting positive voltage inside the cell. The instructor compares the biological concepts with semiconductor physics, emphasizing the similarities in the mathematical models used to describe both systems. The lecture concludes with a comprehensive overview of the electrochemical potential and its implications for cellular function.