Control of Cell Volume and Membrane Potential

Slide 2

Basic problem

Basic solution

The cell at steady state

Typical ionic concentrations

Active pumping

Na+-K+ ATPase

Na+-K+ ATPase

Osmosis

The Nernst equation

Only very little ion transfer

Electrical circuit model of cell membrane

How to model Iionic

Two common current models

Electrodiffusion: deriving current models

The short-channel limit

The long-channel limit

Volume control: The Pump-Leak Model

Charge and osmotic balance

Steady-state solution

RVD and RVI

RVD and RVI

Lots of interesting unsolved problems

Ion transport

Steady state equations

Transport control

IMCD cells

Active modulation of the membrane potential: electrically excitable cells

Hodgkin, Huxley, and
the Giant Squid Axon

The
reality

Resting potential

Simplifications

Steady-state vs instantaneous I-V curves

Example: Na+ and K+ channels

K+ channel gating

Na+ channel gating

Experimental data: K+ conductance

Experimental data: Na+ conductance

Hodgkin-Huxley equations

An action potential

The fast phase plane: I

The fast phase plane: II

The fast-slow phase plane

Oscillations

Where does it go from here?