Cardiovascular | Electrophysiology | Extrinsic Cardiac Conduction System

Ninja Nerds,

In this lecture Professor Zach Murphy will be presenting on the Extrinsic Cardiac Conduction System. This will conclude our discussion on the electrophysiology of the heart. We hope you enjoy this lecture and be sure to support us below!

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[tuly]

I can't believe you don't have more views or subscribers!! You are a life saver and super informative, thank you so much for doing this in the best way possible!

[virginiabennett]

Thank you much!!! My professor had us watch a 6.5 minute video where it sounded like Siri explaining someone's dissertation on how this all works. My sympathetic nervous system kicked in sending a slew of epinephrine and norepinephrine from my adrenal medulla into my autorhythmic cells, flooding them with Calcium positive ions, and giving heart palpitations and a super fast heart rate (tachycardia), an external physical sign of my internal rising fear because I absolutely could not understand the material. After watching Part 1 and Part 2 of your videos, my parasympathetic nervous system encouraged my vagal nerves to release acetylcholine, inhibiting the flood of calcium positive ions, allowing the troponin to reattach to tropomyosin in my contractile cardiac cells, allowing them to relax, and therefore returning my tachycardic heart rate to a normal, confident, Ima-ace-this-bish heart rate. :) These videos are truly genius, and my autorhythmic and contractile cells and I cannot thank you enough!

[mustafahy]

I remember back in medschool trying to study and understand this for days, where were you 10 years ago you could've saved me much time and effort.

[ASalfity]

Brief Table of Contents:

1:00 – Beta 1 Adrenergic Receptor (Nodal Cells)
1:20 - Sympathetic Nerve
2:10 - Adenylate Cyclase
4:20 - Tachycardia (More than 100 BPM)
5:10 - Parasympathetic Nervous System
7:30 – Bradycardia (less than 60 BPM)
9:40 – Vagus Nerve
10:15 – Chronotropic Action (Positive and Negative)
10:50 – Contractile Cells
12:10 – Phospholamban
16:50 – Heart Rate Graph
18:35 – Refractory Period Graph

A twisted way to help you remember is that the Sympathetic nervous system Stimulates and the Parasympathetic nervous system Paralyzes. You may wish to add this to the description or create your own more detailed version. Thanks for these videos.

[lucassena]

Mr, i’m from brazil and i study medicine in argentina, i just took my time to comment here and i wanna say that:
You are really changing people life, you have such a good way of explaining, thank you for all this knowledge and keep on the good work!!

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This guy enjoys teaching..watch him smiling and subtly laughing while explaining simplified complex theories!! WOW.. amazing.!!

[tristanvandenberge]

Dude

I'm a second year med student (bachelor's, Dutch system) and after having to re-do the cardiology course and still not getting it, hating it, studying to keep my head above water and just get this part over with, I landed on this channel since uni was just not cutting it guidance-wise. After watching your videos for a couple of hours, I got to really understand the subject (never has the (basic) subject matter been explained so clearly and have relations been made clear). The understanding got me to suddenly enjoy cardiology so much that I watch these darn videos for entertainment instead of ducking Netflix.

You're right man, it IS cool. Your inspiration got me rid of some small career choice doubts. Big thumbs up dude.

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[RA-omck]

Thank you so much for the video. Towards the end it would have been great to mention that sympathetic stimulation increases the slope of phase 4 on the action potential graph of the pacemaker cell driving it closer to the threshold. Parasympathetic decreases the slope of phase 4 on the graph driving it further away from the threshold. You drew it, but it is worthwhile to have mentioned it. Many students do not understand the word slope.

[christodavis]

During these quarentine days..it really help me a lot to understand much of this topic..u r really a genius 😎

[hazwithy]

this guy is getting me through my medical thank you !