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Pacemaker Potential and Pacemaker Cells – Heart Rate and Electricity

by Thad Wilson, PhD
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    Let's start looking at action potentials by looking at pacemaker cells. Why? Because they generate the initiation of the heart rate. So, let's start off with what that particular action potential looks like. We start off in a resting potential. We call that Phase 4. Yes, yes, I didn't make a mistake. They call it Phase 4. Seems odd. We start at phase four. Yes, we don't start at zero. We don't start at one, two or three. We start at four. Who knows? That's the way it is. If we go from Phase 4, which is the beginning of the process, we have a number of currents that are present. We denote currents as Is. Just like we use g for conductance, we use I for current. We have a few currents that are active during rest. The first one is called If and this is a denotation of current through the funny channel. Boy, I didn't name these. I didn't start off with – I started off with four and I didn't name this. It's the funny channel. The funny channel is actually a channel that they now call HCN. This HCN channel allows for traveling of cations through that particular channel. This is why you have an upward slope in Phase 4. Once you have starting to travel upwards of phase 4, which is primarily cations, primarily sodium, you will then also open up a couple of calcium channels. And this further depolarizes the membrane. Remember, depolarize means you're moving upwards in your membrane potential. You notice that in this particular time, we have a dotted line called the threshold. Once we reach threshold, we’re going to have a fast change in membrane potential. So what are we going to learn from this? Remember that we have...

    About the Lecture

    The lecture Pacemaker Potential and Pacemaker Cells – Heart Rate and Electricity by Thad Wilson, PhD is from the course Cardiac Physiology.


    Included Quiz Questions

    1. I Ca (L)
    2. I Ca (T)
    3. I K
    4. I f

    Author of lecture Pacemaker Potential and Pacemaker Cells – Heart Rate and Electricity

     Thad Wilson, PhD

    Thad Wilson, PhD


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    By Isabel P. on 22. May 2017 for Pacemaker Potential and Pacemaker Cells – Heart Rate and Electricity

    Thank you!! Finally understood this after years of studying it over and over again... I can't believe it was so simple!! Thank you so much!