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Myocyte Conduction Pathway and Atriventricular Block (AV) – Heart Rate and Electricity

by Thad Wilson, PhD
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    Let's talk through how you get a signal from the SA node, all the way down to these cardiac myocytes. There are some specific pathways, by which you’re going to go through. So, you start at the SA node, you go to the AV node, you go down the Purkinje fibers and that is how this process works. But I'll tell you something. Some of the places along this conduction pathway are faster than others. So, let's start with the fastest stuff, right? The fastest thing we have are Purkinje fibers. Purkinje fibers are really quick conductors. So, as so soon as they get electricity, boom, they move it right on. Right behind that is the right and left bundle branches. So, those are the areas right along the septum. They also conduct electricity very rapidly. The ones that conduct it a little bit are in the atrial muscle and ventricular muscle. This is kind of a moderate level of electrical conduction in terms of speed. What’s the slowest – what is the slowest process in this whole thing? The weakest link. It is the slow portion and that is the AV node. So, the AV node slows things down. It is a slow conductor, while the other things like Purkinje fibers move really quick. So, it just depends upon which area you are in the heart, of which of these particular conduction velocities will allow for the process to happen. If you think about it, it makes sense that these will have different rates. Why? Well, first, you need to signal the top portion of the heart to contract, but you need to wait until the ventricles fill up before you contract them. And that's one of the primary purposes of the slow AV node that allows it to...

    About the Lecture

    The lecture Myocyte Conduction Pathway and Atriventricular Block (AV) – Heart Rate and Electricity by Thad Wilson, PhD is from the course Cardiac Physiology. It contains the following chapters:

    • Myocyte Conduction Pathways
    • Possible Sites of Conduction Blocks

    Included Quiz Questions

    1. Purkinje fibers at 4 m/s
    2. Atrial muscle at 0.5 m/s
    3. Bundle branches at 2 m/s
    4. AV node at 0.05 m/s
    5. Ventricular muscle fibers at 0.5 m/s
    1. AV node
    2. Ventricular muscle
    3. Purkinje fibers
    4. Atrial muscle
    5. Bundle branches
    1. Dromotropy
    2. Lusitropy
    3. Inotropic
    4. Chronotropy
    5. Hypertrophy
    1. Third-degree AV block
    2. First-degree AV block
    3. Type I second-degree AV block
    4. Atrial defibrillation
    5. Type 2 second-degree AV block

    Author of lecture Myocyte Conduction Pathway and Atriventricular Block (AV) – Heart Rate and Electricity

     Thad Wilson, PhD

    Thad Wilson, PhD


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    A little unclear
    By Linn F. on 29. May 2017 for Myocyte Conduction Pathway and Atriventricular Block (AV) – Heart Rate and Electricity

    I've been watching through and writing notes your videos til this one (thank you so much for making this easy and understandable while staying on a detailed level that I need for my exams) BUT there's something that wasn't that clear to me. What did you mean on the slide about type 2, where you mentioned Mobitz? Sentence nr2 of the 3 didn't make much sense to me.