Action potentials in pacemaker cells | Circulatory system physiology | NCLEX-RN | Khan Academy
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- čas přidán 6. 10. 2012
- Find out how the pacemaker cells use the movement of sodium, calcium, and potassium to get your heart beating! Rishi is a pediatric infectious disease physician and works at Khan Academy. Created by Rishi Desai.
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Absolutely brilliant. I have subscribed!
Please Overdrive suppression explain
At what point does the sodium and calcium leave and at what point does the potassium enter? This example model would lead to a swelling of the cells with Na and Ca ions and the cell would be depleted of K within a few cycles...
This is a very simplified version for non med people
@@life42theuniverseThis is introductory. Read further and do some research.
These videos are so wonderful as a study aid for medical school! I can always come back to these to get down to the most basic concepts and extrapolate them to things such as anti-arrhythmic pharmacology. THANK YOU SO MUCH!
cbcCarissa Wilkins
I'm doing exactly the same lmao
Doing it right now
I like this guy that helps Khan. His voice, straight forward, nice. easy to learn
Potassium reenters the cells by the Na/K pump which is ALWAYS working to keep the potassium levels nice and high in the cells.
I studied biology in undergrad; I did well on the MCAT; I am a second year in med school.... and this was the best explanation of how action potentials work I've ever seen. I can't even begin to thank KhanA for their work.
Thank you!!!!! I LOVE khan academy videos! My sister-in-law introduced them to me recently because I was getting rusty on a few things. They're so easy to understand in comparison to how I learned info in nursing school. Education is a big part of a nurse's career. With these videos, I feel I can educate my patients better.
0 stage (action potential) is because of Ca+ coming in(,not bc Na+ coming In as in cardiac myocyte)
stage 1 and2 is not present in pacemaker cell because pacemaker do not have platue
stage 3 is repolarization because K+ out leaving -ve inside
stage 4 is activation of If Na+channel (because of repolarization by K+ out ward)
now this Na+ wil depolarize to threshold (not action potential) to open Ca+ channel these Ca+ entry (or stage one again ) is action potentional
(during whole phase ions are actively transporated to their orignal concentratioout and inside by Na K atpase pump and contratranprrt
first of all, what cause the action potential is ( sodium and calcium ) , first there is ( slow sodium channels ) that make the potential reaches " threshold" and after that a channels call ( sodium-calcium channels ) activated , thus causing action potential ( both the sodium and calcium ) ( source ; Guyton, Textbook of physiology chapter 10, 117)
i studied this for 6 years and still can't understand this shit
Good job!!! I wish our teachers would explain things like you. Than I would start going to their lectures...
These really are the most educational videos you're going to find on youtube, great work!
K. Kl l
Thank you so much, for this video! It helped me a lot to understand cardiac electrophysiology !
I have never been able to grasp the concept of action potentials within the cardiac muscle cell no matter which professor for A&P 1 or 2 trying to explain it but this video with the diagrams and everything have single handedly saved my life lol
There's a reason why you joined the Khanacademy team; you fit right into Sal's "intuitive" (not to mention that you sound a bit like him) way of teaching. Thanks to all of you guys for broadening the library.
Thank you so much for the videos. You make complex materials so much easier to understand and explain things which are often missing from textbooks. I also love your voice.
A great lecture. Thank you so much!
This video, as well as the one on cardiac myocytes have been very helpful to me. However, in my Anatomy & Physiology course there are some pieces to the pacemaker cell action potential that were not in this video which I feel would be important to add. Terms:
Funny Channels
T-type channels
L-type channels
Early drift
Late drift
These pieces were shown in the video but not named.
+Brittany Montero really helpful also for me
Fantastic revision for IBHRE!! Thank you!
Wow. What a wonderful explanation! Thank you so much!
Wonderful explanation. Thank you for your efforts.
THANK YOU for explaining all the math!!! Most teachers don’t even care about it or to explain it, now the numbers make more sense now and it’s easier to grasp the concept
So clear thank you!
You vids are sooo helpful. Im studying at university and think the vids are a reallu gd was to get to grasps withbthe basics. Thank you
amazing video. English is my second language but you really explain this so simply!
Khan Academy for medical school! I love it! Thanks for the awesome work!!
You make this less confusing, thank you!
thanks a lot for these videos as I learned about how , the human heart works.....thnks
Thank you so so much! This is very clear!!!
So, there is a difference between action potentials in pacemaker cells and action potentials in cardiac myocytes?? Or was it just an example to use different ions coming into or going out the cells?
Gülay Yalcin there's a difference. Pacemaker cells are special modified cardiac myocytes.
Gülay Yalcin what I've read that is pacemaker cells unlike cardiac myocytes do not need any stimuli to generate Action potential.
They are different. There´s another video of Khan academy about the pacemaker action potential, check it out.
If only I had lectures like this! Easy to follow. Thank you for posting!
Of course you don't. I don't either. It's not necessarily that your lecturers are bad or unskilled - it's just that khan academy team is one of a damn kind and it is an absolute blessing for us to have access to them
thank you this is incredible!!!!!
What about the Bachmann's bundle and the internodal tracks? are they made up of pacemaker cells? If so, does that mean that those cells could fire spontaneous action potentials if the SA node, AV node and purkinje systems are not working? if they're not made out of pacemaker cells, then are they just made out of normal cardiac muscle cells?
Thanks man, really good explanation!
simple and very helpful! amazing.. thank you
Loving this series of videos!!!!!!!
After so many years, i understand it now ! Thank u very much
Thank you so much, this was very helpful :)
Thanks man, excellent explanation!
THANK YOU!!! Now I get it. You make this very easy to understand :)
I love these lecture or videos that you post thank you and easy to understand
thank you ^^ I really needed this to understand :)
thank you a lot , so clear!
thank you! I have a midterm in 2 days and you truly explain better than my prof!
This looked complicated and sounded complicated, but sir you made it simple and now I understand it. So I thank you for been such a good teacher :)
This guy is intelligent and very knowledgable (and interesting), but long on hand waving and short on complete, logical explanations.
thank you. It was really helpful.
I loved loved this...this is absolutely appropriate and more
thank you, excellent demonistration
I really admire it.its awfully good
the 4, 0, 3 numbering system is used because in 'non pacemakercells' the 0 represents Depolarisation and the the 3 represents repolarisation and those two numbers represent the same events in 'pacemaker cells'. Thats why they chose those specific numbers.
So wonderful so amazing & so lovely
Thanks, I understand this so much better
Thanks.
What playlist is this part of?
amazing video. thank you very much
so when the ca++ and the Na ions goes inside the cells and the K out, do they stay in there until the next action potential reversing the ions back to where it originally were located with Na and Ca++ out outside the membrane and the K in?
Thank you sir for sharing such a great video..but sir I have a question..why are the limits +10mV and -60mV?
You guys are awesome! Thanks :)
I am really really appreciate it thank you so much!!
Brilliant!
Amazing teaching, thanks for this
can you make a video explaining (If) channels or funny current channels
i just wanna say how great you are my god!! So wondrous. God created for us these cells and with high accuracy !! nobody can create these cells just a god
Amazing video! But just to make sure, the Na+ voltage-gated channels are always open no matter what the other channels are doing, right?
Thank you!!!!!
Keep up the good work !!!
The action potentials in the SA and AV nodes are largely due to Ca++, with no contribution by Na+ influx
(Ganong's Review of Medical Physiology, Twenty-Third Edition
Chapter 30 -Origin of the Heartbeat & the Electrical Activity of the Heart. Sub topic- Pacemaker potentials.)
Please explain this
Sodium ions cause the pacemaker current in cardiac cells, which causes the membrane potential to change from -60 mV to reach the threshold potential of -40 mV. This slow influx of sodium ions through the hyperpolarization-activated cyclic nucleotide-gated channel (HCN channel) generates the pacemaker potential. The slope of phase four determines heart rate and is different for pacemaker cells in different regions. For example, SA node pacemaker cells depolarize at a rate of 60 to 100 per minute, while the AV node at 40 to 60 per minute.
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Really good, doing my MBBS and our cardio lecturer is shocking. Would you be able to explain next time how calcium exits the cell? is the potassium sodium pump the slow "leaky" sodium channels that trigger threshold or are they different?
this guy. is amazing.
Thank you so much .
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is the automaticity character due to inflow of Na as you said in the video or slow inward Ca currents ?
en.wikipedia.org/wiki/Cardiac_action_potential#Phase_4
I had the same question.
Apparently, it's due to both. (Along with a decrease of Potassium exiting).
"This pacemaker potential is predominantly due to increased inward current of sodium (Na+) through voltage-dependent channels, but also an increased inward calcium current and a slowly decreasing potassium outward current."
I hope it helps :)
awesome!!!!
Can someone explain to me why during phase 3, if K is leaving the cell how does the cell's mV become more negative. If K has a - charge than in my mind the cell would increase it's + charge. Thank you for anyone's help. Thank you for the video as well!
because K+ is effluxing
Thank you very much! You have a knack for explaining things well.
My only comment would be on your use of the word "salt" synonymously with sodium. Chemically speaking salt would mean an anion and cation, and if you were using it to mean "table salt" it would include chloride as well, not just sodium.
I commented on another video as well so apologies if there is an answer there. I am a bit confused about the voltage-gated channels. So at -40mV the Ca2+ channels open, and presumably remain open, until +10mV is achieved, at which point they shut and the cell tends towards a more negative charge again. What stops Ca2+ channels opening again the moment the cell's charge drops slightly below +10mV i.e. why do they stay shut until the next upwards rise to -40mV. Indeed, why do they not open again as the charge travels back down past -40mV?
EDIT: I assume this relates chemically to the absolute refractory period but it is unclear to me what prevents the voltage gated channels from reopening.
Literally understood it for the 1st time
thank youuu ✨
great!
Awesome way of teaching 😍😍
Amazing knowledge
I don't understand how this can work. If Na is flowing into the cell and then Ca flows into the cell and K flows out of the cell. All the electrolytes need to go back. K needs to get back in the cell, Na and Ca needs to move back out of the cell. The switching back of all the electrolytes is not talked about. How can we just start over if all the electrolytes are not in the correct area?
excatly... it explains only one cycle
Basically there are two kinds of K+ channels: rapid delayed rectifiers (IKr) and inwardly rectifying (IK1). IKr is the primary channel, so there's a net outward, positive current (making the inside of the cell more negative), and this is repolarization. IKr closes when the membrane potential is about -85 to -90 mV.
BUT the IK1 keeps open throughout phase 4 (allowing K+ to return inside).
The Na/Ca exchanger and Na/K pump also help to restore ion concentrations. So like, the Na/K pump is an ATPase that pumps both ions against their concentration gradient, which means it'll pump Na+ out & K+ in, thus returning everything to how it was!
what about Na?
The Na+ and K+ ions are "replaced" by Na/K ATP-ase which pumps 2 K+ ions into the cell for every 3 Na+ ions out of the cell and re-establishes these ion gradients. The Ca+ ions are also pumped out of the cell in a similar fashion. Bottom line- there are many ion channels and other membrane proteins at work. This is just a simplification of how "action potentials" work in the nodal cells.
Thank u very much :)
incredible
Thaaaaaaanx soo much :) very helpful video
the world need more heroes..... who have gifts in explaning. the XPLAN-MAN!!!!
If potassium is a positive ion, then why would the membrane potential be negative if it was the only ion moving and out the cell?
Thank you so much for this helpful video! ❤️
@3:00, where are you getting the numbers from?
hello sir !when will the Na+ ion move out bcoz i see here it's always moving in.
This is excellent.
So, does this mean that pacemaker cells and cardiomyocytes don't have refractory periods? or time for channels to "recover"?
what about the plateau where the ca2+ and the k+ causes a stall before repolarization? can you explain what's going on during that section? it would be most appreciated and help things click a little more for me. please and thanks :-)
THANK YOU!
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