I have a question about SA and AV node, did my research, asked my professor, but I still do not have a good gasp of it so I think posting it under cardiology is my best bet.
So I was told by my professor that under normal condition, each time SA and AV node start phase 4 depolarization at the same time (since they both have funny cation channels and unstable RMP). SA node fires first, AP is conducted through AV node. Once AP reaches AV node, it over rides the AV node. With each time, AV node always tries to be the pacemaker (by starting phase 4 depolarization at the same time as SA node) but then stops by SA node. She also said SA node is the only thing that keeps it from causing an arrhythmia (both fire at the same time) by firing at a faster rate.
From the systems I have learned so far though, there are usually more than one protective mechanism to keep something from going wrong. The fact that we have both SA and AV nodes try to fire at the same and be the pace makers, with SA node as the only thing that keeps it from happening, with something as important as the heart, it does not make sense to me.
Also, does that mean AV node arrhythmia is more common than others since it sounds it is constantly excitable and try to be the pacemaker?
Thanks.
So I was told by my professor that under normal condition, each time SA and AV node start phase 4 depolarization at the same time (since they both have funny cation channels and unstable RMP). SA node fires first, AP is conducted through AV node. Once AP reaches AV node, it over rides the AV node. With each time, AV node always tries to be the pacemaker (by starting phase 4 depolarization at the same time as SA node) but then stops by SA node. She also said SA node is the only thing that keeps it from causing an arrhythmia (both fire at the same time) by firing at a faster rate.
From the systems I have learned so far though, there are usually more than one protective mechanism to keep something from going wrong. The fact that we have both SA and AV nodes try to fire at the same and be the pace makers, with SA node as the only thing that keeps it from happening, with something as important as the heart, it does not make sense to me.
Also, does that mean AV node arrhythmia is more common than others since it sounds it is constantly excitable and try to be the pacemaker?
Thanks.
