LOL - "I hope this isn't too confusing" I've been a cardiac nurse for 15 years and this is the clearest explanation I have ever received!! Thank you:)

this is by far the best ecg and heart function explanation in history.

I just got back from my physiology finals...and i ACED it...all thanks to you...thank you man :D

You got me through my freshman semester of PA school...now you're getting me through my sophomore semester. You rock, man! Thanks!

Adding onto his notes in more specificity: The unstable membrane potential for which these pacemaker fibers start is known as a pacemaker potential since the fibers never truly rest at a constant value. This would be the beginning of his stage 4 at about -60mV. These pacemaker fibers contain channels known as I-funny channels, that are different from other excitatory tissues in that they allow Na ions and K ions to both pass. When these channels open at negative values, they allow for a greater influx of Na+ than an efflux of K+. This influx of Na+ slowly begins to depolarize the fibers, which can be seen in his slow incline along phase 4. As the fibers become more inside positive, the I-funny channels slowly start to close. It is at this point, right before the sudden inclination, that a specific set of Ca2+ channels open, allows Ca2+ to move into the fibers and continues to make the auto-rhythmic fibers more inside positive. When the pacemaker potential reaches threshold, a different group of Ca2+ channels open, allowing a sudden rush of Ca2+ into the cell and creating the steep 0 phase. The steep depolarization due to Ca2+ is a key characteristic of pacemaker cells. In other cells, the steep depolarization phase is due to a net influx of Na+. At the peak, these Ca2+ channels close, and slow K+ channels open. The rapid efflux of K+ is responsible for repolarization (his phase 3). This phase is similar to other excitatory cells. Similarly, the small "under shoot" at the end of the steep decline signifies the closure of K+ channels. Among other things, the time it takes for depolarization of pacemaker cells determines the heart rate.

Armando, I am truly grateful for your videos. Your videos have help breakdown complexing subjects into bite size clear information. You have an amazing way of teaching the material and thanks to your videos I made it through my Pathophysiology course. Thank you again for taking the time to help me and so many who struggle with reading words on a textbook. Thank you again and God bless !

This channel is getting me through Anatomy and Physiology. Bless your soul!

you have saved so many lives with your videos i hope you know that!

I'm so happy I saw this video !!! I'm very grateful, thanks so much it was excellent an so are you. Life will multiply you good actions !!!

This is the first time this has made sense to me - many thanks!

I'm just in awe. lol. such skill going on here. thanks for the video!

This man's vids saves me in Physiology. Thank you so much.

This is an awesome study aid. Thank you so much for all the uploads!

i hope you're not busy, but i really need the "NEXT" video as soon as possible. Thank you so much for all your other videos, you're really great!

you are amazing!! my college professor is no where as clear as you are. it took 2 classes to cover this subject and you did it in less than 30 min.

great video, thank you for taking the time to post this material it has been very helpful.

Been struggling to understand this for my A&P exam. Im so happy i found your channel again. Subbed so i never lose it again xD

Thank you so much for doing these man! Absolutely fantastic as a study guide!

Watched whole videos from the top of Himalaya to ease through the medical exams.bravo

you can't imagine how thankful I am... my exam is tomorrow and I was crying cause I didn't understand it till I found your video and it appears clear like water... thanks you so so much!!!!!!❤❤❤❤❤❤❤❤❤❤❤

Armando gets zero hate comments. Whoever comes here goes away with clear concepts.amazing teacher.thank you sir ♥️

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You are the Godfather of modern medicine

This video is really well done and explained, thank you very much my friend

So much clearer than the school lecturer. Did not understand anything before watching your videos.

Congrats for such a good vid, nice electrocardiographic correlation!

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This is probably a minor and inconsequential point, but at ~8:50, Armando mentions phase 0 (the steep upward curve) and states that the influx of sodium is the contraction of the ventricles. While this phase of the action potential is the depolarization of the membrane, the voltage-gated influx of calcium (Ca) ions (via the L-type channels) starts at about -40 mV and is more prolonged than sodium influx (lasting throughout phase 2). The Ca ions which influx during this phase trigger a massive release of Ca ion storage from the sarcoplasmic reticulum, which is responsible for ventricular contraction. Therefore, I believe it would be more precise to say contraction of the ventricles happen during phase 2. Source: Pathophysiology of Heart Disease, L. Lilly.

Very nice video. Especially lining up ECG with contractile cycles (systole/diastole)

Love your videos, they are really helpful for reviewing topics for exams! Thank you :-)

thank you so much for this video and the image of your notes, so helpful!

Thank you so much for helping students like me. Only searching for good teacher 🙂

I love you so much man....keep impressing me Armando 💖

Sir u r amazing... Love from India!!!!

It helps alot!! Thank you!

This is really helpful :)

thanx for providing the image...And for everthing else.. :)

thank you! simplistic explanation!

very very helpful ! thanks for d tutorial !

this is good armando

Nice vid thanks man, m trying to relearn all this stuff

Thank you!! Very helpfull

I love you man

Thank you very much for this vid.

Thanks armando!!

so does R correspond to the first heart sound, and T the second heart sound?

Thank you so much !!!

Thank you soooo much🙏🏻

The greatest!

Cmiiw : SA node -> AV node -> Bundle of Hiss -> Purkinjae Fibers Location, SA : Crista Terminalis - Atrium Dextra Posterior AV : Trigonum Koch - near A-V Valve Bundle of Hiss : Interventriculare Ceptum Purkinjae Fibers : spread in Miocard Ventricle

great vid, keep em coming, just please make sure everything youre writing/saying is correct by reviewing your work

super duper lecture....u r great

I enjoy watching the VERY informative videos. Do you have one about the pericardium anatomy?

The videos are just amazing and so to the point..also Please post some detailed videos on CARDIAC ARRTHYMIAS and ANGINA PECTORIS..and if it has already been made..please provide the link..unable to find it..

I think you are so skilled

Thanx for ur effort man. :-)

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Nice drawing skills man!

Ucan draw!!&U know the material 😋 thankU 4 sharing💖

very very very very ......... Great work , u have a genius creative mind (prefrontal cortex :P ) that connects all things together in a simple way ,,, I really love this way of looking at things thanks very much man , u are a hero :D

Lov u sir great job

Very nice videos; kindly make a video on EKG also. Thanks.

thank you

Did you make th video explaining whats going on with the heart (visually) when looking at the ECG?

GRACIAS

ok...one question right,,,for the ventricle graph..first depolarization means filling the with positive charge..so how is phase0 systolic when there is rapid depolarization....could you kindly explain that as soon as possible

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if you look into the period of the cardiac cycle, there is about 0.3 sec when four chambers are all relaxed and waiting for blood coming into the atrium.I think that area should be shown longer. thank you!

May i know what reference book/s you are using kind sir?

thanks god bless you

thaaaanx it made alot of sense now..ive been looking for the video next to this one but i couldnt find it could u please tell me how to find it..many thanx

Hi, good catch when you said atrial diastole instead of ventricular diastole. But if you want to add in, the S4 sound should be heard right before the QRS complex. Also when you drew the cardiac myocyte action potential on top of the EKG, shouldn't phase 3 include the T wave instead of ending at the T wave, since the T wave represents ventricular repolarization.

Is the bundle of his the same structure as bachman bundle, or is it different? Thank you!

Thank you for this amazing video but i want to point out about the action potential of the SA node, the action potential peak reaches +10 not 0, otherwise there will be potential difference between the charges if it stops at 0

I graduated school because of the videos on KZfaq just write notes and study these examples I am a licensed EKG Technician

excellent

the "HAWT" LOLZ!

Mr. Richard Adetoye, there's no reply option to your comment so I'll just answer you question here. When you mean systolic, there is contraction of ventricular muscles to push the blood from the ventricles to the pulmonary artery or to the aorta. Depolarization means making the membrane potential to become more positive to make muscle contraction possible. Phase 0 means depolarization of the ventricular muscles thus is part of the systolic phase. Hope this helps.

thnaks alot

What's the relation between the first and second graph?

hey man great video. I just have a quick note about the SA node phases. In phase 4, it is true that the L and T types open up channels but they do so after it reaches -40 mV. From -55 to -40 mV is produced by something called a funny channel which is activated by negative membrane potential and this channel bring in Na +. Just wanted to add detail but great video, love your stuff please keep doing what youre doing!

grt diagram it explain and cover all ...bt u can even make it simplier..

very interesting

Good! But can you also tell us about "Renal vascularization"?

I am a Biology Higher level teacher, your videos and teaching skills have really advanced my teaching approaches and bettered learners' understanding and good approach to the most challenging questions. thank you very much, may God bless you.

What's the difference between spontaneous depolarization and depolarization on the first graph,?

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Just one question, in the explanation about the cardiac muscle cell contraction, you say that Na+ stop moving in in phase 1, but then in phase 3 you say both Calcium AND sodium stop moving in, how can the sodium influx stop twice ?

Need videos on heart failure, CAD, rheumatic fever, IHD

your videos really helped.I have a question now, what is the blood flow from the coronary sinus to the femoral artery? thanks in advance