Membrane and Action Potential

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Membrane and Action Potential
2010-05-16 09:11:14
Membrane potential action potential

membrane action potential Rosemay Martin
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  1. What is a potential difference?
    • A charge separation across a cell membrane - a difference (delta) in volts (V). Measured in mV
    • Outside is more positive
    • Inside is more negative
    • Calculated for one ion species by the Nernst equation.
  2. How does charge separation arise?
    Transmembrane concentration differences and the presence of leak ion channels
  3. What is conductance?
    • Leakiness
    • Conductance (Gion) = measure of the ease with which an ion can cross a unit area of 1cm2 of membrane
    • =Po n gamma

    • Po is the probability the channel is open
    • n is the number of channels
    • gamma is the number of ions per second that a chanel can conduct

    If Po = 1, then channels are open all the time and are therefore "leak" channels
  4. How do we calculate the resting membrane potential?
    • The Goldman Equation
    • This takes into account the conductance of the K, Na and Cl and their equilibrium potential, sums it and this = Vm (AKA RMP)