Cardiac Conduction

[BlakeFabian]

Hello All-

I'm currently attending a Paramedic course, and we're going over ECG's & Cardiac Conduction.

Throughout the first couple chapters of my Arrhythmia book, it spoke of the AV Node & AV Junction as one in the same. I then get to my current chapter, and it identifies them as two different things.

My question is, what's different? Correct me if I'm wrong, but aren't they both the same structure; in the exact same spot along the conduction pathway?

Thanks in advance for your help.

 

[Shishkabob]

In all technicality, they are one and the same, yet not. It really just depends on who you ask to define it.

Some would say they are separate, where the AV node itself is the superior portion, while the AV junction (bundle of His) is the inferior portion. The "junction" (His) is where the split of the bundle branches starts.

Some say the AV node is it's own node, while when combined with the bundle of His, it makes up the "junction".

Some just use it as an overlapping term, where they combine the node itself with the bundle of His into one thing, where node and junction are interchangeable.



Both the node and the His have identical intrinsic rates of 40-60, so both can take over pacing.

 

[Voodoo1]

Hello All-

I'm currently attending a Paramedic course, and we're going over ECG's & Cardiac Conduction.

Throughout the first couple chapters of my Arrhythmia book, it spoke of the AV Node & AV Junction as one in the same. I then get to my current chapter, and it identifies them as two different things.

My question is, what's different? Correct me if I'm wrong, but aren't they both the same structure; in the exact same spot along the conduction pathway?

Thanks in advance for your help.

I'm just learning this too, so bear with me and if I'm wrong I would most certainly like to be corrected. The depolarization goes through the AV node down into the AV junction, which splits off into the left and right bundle branches. I don't think that they're two different structures, but it seems to me that the rate of ionization is very different to carry the depolarization.

 

[BlakeFabian]

I'm just learning this too, so bear with me and if I'm wrong I would most certainly like to be corrected. The depolarization goes through the AV node down into the AV junction, which splits off into the left and right bundle branches. I don't think that they're two different structures, but it seems to me that the rate of ionization is very different to carry the depolarization.

I'm confused about your last sentence; "Rate of Ionization?" Please elaborate...
EDIT: Never mind, Linuss clarified for me. Thanks.

Thanks for your prompt answers guys; I now know what to put into my notes.

 

[Voodoo1]

Perhaps I worded that poorly. What I meant to say was that Ca ions are moving slowly through the AV Node and then depolarization continues rapidly through the His Bundle and L/R bundle branches.

 

[BlakeFabian]

Ok, so you're saying the ion itself carries the depolarization through the pathway?

It was my understanding that the NA+ & K+ simply switched interior/exterior positions on/in the cell which creates the depolarization which was then, itself (the electricity,) shot down the conduction pathway?

I know you mentioned Calcium instead of Sodium because it sometimes replaces it as the mineral depolarizing the cell, but when and how often does that happen?

 

[usalsfyre]

Ca is the ion that actually uncovers the actin and myosin binding sites that cause muscle contraction.

In addition, Ca is important in releasing the neurotransmitters that cause the action potential to propagate by activating the sodium/potassium channels that cause depolarization. At the end of the conduction channel there are voltage activated Ca channels that allow calcium in when activated, which then causes vesicles to release the neurotransmitters that carry the depolarization across the synapse. There's a whole host of folks on here who can explain that process better.

 

[MSDeltaFlt]

Hello All-

I'm currently attending a Paramedic course, and we're going over ECG's & Cardiac Conduction.

Throughout the first couple chapters of my Arrhythmia book, it spoke of the AV Node & AV Junction as one in the same. I then get to my current chapter, and it identifies them as two different things.

My question is, what's different? Correct me if I'm wrong, but aren't they both the same structure; in the exact same spot along the conduction pathway?

Thanks in advance for your help.

In all technicality, they are one and the same, yet not. It really just depends on who you ask to define it.

Some would say they are separate, where the AV node itself is the superior portion, while the AV junction (bundle of His) is the inferior portion. The "junction" (His) is where the split of the bundle branches starts.

Some say the AV node is it's own node, while when combined with the bundle of His, it makes up the "junction".

Some just use it as an overlapping term, where they combine the node itself with the bundle of His into one thing, where node and junction are interchangeable.



Both the node and the His have identical intrinsic rates of 40-60, so both can take over pacing.

Yes They are the same and yet different. Not unlike the lobes in the lungs. And since it is different chapters in the same book saying this they will make the distinction however subtle. The "node" is the superior portion of the "bundle". If the node quits, the branches will take over. They take over work in that order. SA node is the first string quarterback. The AV node is the 2nd string. Bundle of His the 3rd string. The Perkinje Fibers? Them's the waterboy.