Membrane Potential: Ion Concentration

by Thad Wilson, PhD

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    Membrane excitability. To understand how excited a membrane can be and I know you’re excited too to learn about membrane excitability. What we really need to do to look at the current changes across any particular membrane is you need to use a recording electrode. Simply, you put a recording electrode one side of the membrane and then on the other, or you put it inside the cell and then ground it. The potential across the membrane allows for some signals to potentially be sent. And interestingly, the signal between or the difference between the membrane and the outside the cell oftentimes has a voltage potential. This voltage potential is determined by the ion concentrations inside and out of the cell. So by knowing the ion concentrations, you can get inside into this voltage change. How does this work? Well, you need to know a few things. So I’m going to use a couple of theoretical examples first and then we’re going to go into some practicals. Theoretically, if we had this bath and we had a divider in the middle of the bath that didn’t allow any ions to travel through. Let’s just label one of them ECF, which is representative of the extracellular fluid, and the ICF as representative of the intracellular fluid. You put an electrode on one side, electrode on the other side of the bath. In this case, we’re using potassium and chloride. In our example here, the number of positive and negative charges is equal. Now, I know if you’re looking at these too bad, you’re telling me, how is that equal? What I’m saying here is the number positives equal the number of negatives on both sides of the bath not that the one side of the bath has a lot more molecules...

    About the Lecture

    The lecture Membrane Potential: Ion Concentration by Thad Wilson, PhD is from the course Membrane Physiology.

    Included Quiz Questions

    1. Hyperpolarization
    2. Depolarization
    3. Less negative membrane voltage
    4. Nothing
    5. An influx of positive ions
    1. The difference in ion concentration between the inside and the outside of the cell
    2. The presence of recording electrodes
    3. The presence of a membrane between two solutes
    4. The presence of Intracellular fluid and extracellular fluid
    5. The presence of selective pores in the cell membrane
    1. A membrane that allows only selected types of ions to migrate across
    2. A membrane that allows passage of water
    3. A membrane that does not allow passage of water
    4. A membrane that allows passage of anions
    5. A membrane that allows passage of cations
    1. The balance of the number of charges across the membrane
    2. The number of ions on each side of the membrane
    3. The number of anions on each side of the membrane
    4. The number of cations on each side of the membrane
    5. The presence of a membrane separating two solutes
    1. ...becomes more positive
    2. ...becomes more negative
    3. ...becomes hyperpolarized
    4. ...moves the recording needle down
    5. ...does nothing

    Author of lecture Membrane Potential: Ion Concentration

     Thad Wilson, PhD

    Thad Wilson, PhD

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