Okay, so today we're going to go over anti-arhythmics. This can definitely be one of the more complicated topics to learn in school. It can definitely be a lot more daunting compared to the other topics. So I did my best to break it down and probably throw in more nomenics than I've had in any other podcast. So hopefully that helps you. So before we get started, thank you as always for the really nice comments, the support for the channel, everybody who reaches out and leaves a nice comment, I truly do appreciate it. So thank you so much. Let's go ahead and get started with antirhythics. So there's four main classes that you need to know, and that's your class one, sodium channel blockers, class two, beta blockers, class three potassium channel blockers, and class four calcium channel blockers. So if you ever forget which class

is which, remember the sentence, Some block potassium channels, some block potassium channels, the letters S, B, P, C, that helps you remember class 1, S, sodium channel blockers, class 2, beta blockers, class 3 P potassium channel blockers.

C, class four calcium channel blockers. All right, let's go ahead and get started. We're going to start with our sodium channel blockers, but before we do, I want to review the cardiac action potential, as it's the foundation to understand how this class works, as well as some of our other classes that will go over today. So the cardiac action potential is complicated, and to make it even more even more complicated, it varies depending on which part of the heart we're talking about. We have an action potential in our pacemaker cells as well as our cardiomyocytes in the cardiac muscle. But I'm going to try to make this as simple as possible. Let's first start with the action potential of the cardiomyosites. Now before breaking down each phase, there's a few simple key facts to keep in mind. First, there is five phases, 0, 1, 2, 3, and 4. Next, there's three players in the game, 3 major ions, sodium, calcium, and potassium, which are all positively charged. And finally, at rest, the inside of the cardiac cell sits at about negative 90 millivolts, making it relatively negative compared to the outside. All right, so let's break it down, starting with phase four, which I like to call the floor. Phase four is the floor. This phase is the resting membrane potential. The cell is electrically quiet. There is some leakage of ions, but overall, to keep it simple, just remember phase four as the floor, as

not much is happening and it's a pretty flat phase.

Then comes phase zero.

This is where the action starts.

Fast sodium channels open up and sodium rushes into the cell, causing the inside to become

rapidly more positive.

This phase causes this rapid depolarization and creates this sharp upstroke on the graph.

Phase zero, just remember, is all about sodium and depolarization.

Next is phase one, a brief but important moment, sodium channels close and potassium, the

party pooper as will call him, begins to exit the cell.

This leads to a slight dip in the membrane potential known as initial repolarization.

Phase 2, potassium keeps leaving like the party pooper he is, but calcium starts to enter

the cell at the same time, which essentially balances things out, and that's why phase

two is known as the plateau phase.

Ultimately though, the calcium channels eventually close, and potassium of course keeps leaving,

leading to a rapid drop in repolarization which is phase

three this big old drop and then eventually the cell returns to its negative resting state and we're

back at phase four the floor so to sum it up phase four is the floor resting state phase zero is the

sodium fueled upstroke to start the party rapid depolarolarization, phase one, initial repolarization,

party pooper, potassium starts to leave. Phase two, calcium saves the day and rushes into

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