Every sentence is literally a ¨punchline¨. I wish schools around the world had the ability to convey the material that way, instead of confusing their students. well done harvard.
@@naglaakhaled5259 I’m currently in grad school and I feel that this statement is 100% correct. During courses, the professor/ textbook throws a bunch of information at you but you really only need the main points to succeed on tests/work outside of the classroom. Universities just need an excuse to keep students in the classroom longer and make them feel as if they ‘need’ all this information and need to pay for ridiculous tuition in order to be successful…
@@tinyr101 It would be wonderful if they turned that around - learned the main points- the bare bones first and THEN fill in all the details. It not only could save time but lets you organize information in a more logical manner. You'd retain alot more. Because throwing it all at you at once... It defeats the whole purpose. Memorizing words and phrases without understanding them is why kids forget half the stuff they needed just to pass a test.
I wish everyone well for the upcoming test! You got this! *Update: I'm now in college and I found myself coming back to this video since I have an exam tomorrow. Still extremely helpful!
@@JonLolattemove along then… not everyone learns the same way. Also..condensing some things into less time isn’t always superior. Soemtimes concepts are missed.
@@mbalensiefer "open transcript" is good, but it is sometimes *better* to write your own notes from what you're hearing, as doing so likely 'sets' the info into your brain better, I think.
As a first year neuroscience student, my lectures on the introduction to this topic was covered over 3 hours and was very confusing to understand. This managed to keep the level of detail needed whilst keeping it simple and also under 15 mins... Thank you so much, this really helped.
In my class they don't explain this stuff easily and non-complicated. This is like a dream, where all the complicated parts are filtered out and all the important things are here. Thank you Harvard this should be in all lectures and lessons about neurons
I’m on page 4 of notes! I can’t believe how much this video is helping me understand what I believe is going to be a large topic on my midterm for an SFSU psychology course titled “Perception.” I’ve been struggling to conceptualize brain structures and brain activity that is now included in my courses. I’ve never seen any of it before and have had to slowly teach myself through videos like this when, even after re-reading the dense textbook, I still struggle to keep it all clear. As a very passionate psych undergrad who has never had to take chemistry or any class past intermediate biology, this video made me feel like I really missed out on appreciating science classes more because now that it was explained in a way I can understand, it blew my freakin mind. God I love learning.
If anyone is wondering, there are things called leaky K+ gates that always allow a little bit of K+ ion movement across the membrane. This is how the resting potential is restored after hyperpolarisation (when it goes to negative). Because it's so negative inside the cell (below the resting potential of -70mV) K+ ions will move into the cell because of the electrical gradient, sodium ions can't their gates are shut. This movement of K+ ions into the cell makes it more positive and restores the resting potential. The sodium potassium ion pumps do help a little to maintain the electrical gradient, but mostly they keep the chemical gradient (Na+ in high concentration outside, K+ high conc. inside) with the leaky K+ (how many / how leaky they are) determining the electrical gradient and therefore the resting potential. EDIT: As pointed out to below there are leaky sodium gate to there are just more leaky potassium gates so the over all movement of ions = more K+ ions move than Na+ ions, but the effect is the same, there is a net movement of K+ ions into the cell. Or as below: "I think there are sodium leak channels as well. Sodium is constantly leaking into the neuron to make the membrane potential less negative. This is why there is the Na+ K+ pump to establish the -70mV potential, because without it the Na+ and K+ will just leak according to their electrochemical gradient. However, during hyperpolarization, the electrochemical gradient is so large that the leaks are leaking ions faster than the pumps, that is why the membrane potential can go back to -70mV. Sodium leaks and potassium leaks should be different though. Sodium leaks are protein channels but potassium leaks are holes in the membrane. "
Sorry, can you explain this better? I am not understanding how the potential is restored again after hyperpolarization. If 3 sodiums and 2 potassiums pass through, wouldn't the cell be losing 1 negative ion all the time, making it even more negative?
@@booyah9402 losing a net of one positive ion and making it more negative yes. The K+ gates "leak" a little bit. These gates are not the ion channels pumping the 3Na+ / 2K+, they are gates not channels. They stop most the K+ ions moving when shut, but a few still get past even when shut. When the cell becomes very negative on the inside the electrical difference (the potential difference across the cell membrane) is large enough so K+ ions are forced back into the cell through the K+ ion channels. This is moving from low conc. of K+ ions on the outside to high on the inside, so is moving against the concentration gradient and how diffusion would work, but the electrical difference is so big it pushes positive K+ ions into the cell to restore the electrical gradient. NA+ ions can not be pushed into the cell as their gates do not "leak". Did that help?
@@booyah9402actually 3 factors contribute to RMP: 1.Na+/k+ pumps. 2.leaky k+ channels 3.leaky Na+ channels U must know permeability of k+ is much more than Na+ because of the presence of large amount of k+ channels than Na+ channels on membrane (approx. In the ratio of 100:1) As a result the cell membranes is significantly more permeable to k+ than to Na+.
In that case you can consider, more sodium ion enter the cell during depolarization than potassium ions that goes out during repolarization. @@booyah9402
Thank you. I was confused by the last part of the video where it says pumping 3 sodium out and 2 potassium in restores the cell from hyperpolarized state to resting potential. I think that last part is a bit misleading since the pump always makes the cell more negative.
as a homeschooled kid making my own cutriculum, thank you for this resource. i learned about ion channels the other day and was like “wtf those things do” then was looking into the specific cell functions of neurons and thwy came up bigtime. everything is connected
great video, i understand why Harvard students are so smart, if your explanations are this good online, I cannot imagine how great the lecture are in person.
I am 14 and obsessed with a level psychology: This video was very useful, particularly for clarification and being clear and concise! For anybody confused: Basically the dendrites are decorated with synapses, which don't quite touch the next axel, but have literally less than 1 millionth of an inch between them. The dendrites decide whether to pass the stimulation on, and if yes, then the process begins. The stimulation is passed through the cell membrane (soma), through the axel (which is often covered in a layer of protective fat called the myelin sheath) where the action potential then reaches the axel terminal, and the action potential "jumps" across the synaptic gap and into there receptor sites (like a key fitting into a lock).
I was so baffled by the Neuroscience introductory class. This video made me understand the process so easily. More videos on topics like this are appreciated. Thank you...
A complex phenomenon explained in ease. Slow steady and clear explanation with beautiful animation which we can actually visualise. Thanks a ton for making the learning so simple.
This is a FANTASTIC EXPLANATION! It includes so many helpful details that are simply not covered in other videos about this subject. Thank you so much!
@@نورالإيمان-ع8ذ why does the universe have to be created? If it was created what created the creator? If the creator could be deemed eternal, why couldn’t this universe simply be eternal?
@@F8LDragon2I think it is a circular expanding energy…not some “god” in the sky like many religions made. Because of so many dogmatic ideologies, often used to control and suppress people (and yes, in some cases to try to explain the unexplainable)…to often people are entirely turned off by the idea of a greater force, especially when paired with the name of “god”. That word, label, is so loaded. I do believe there is creative force, that does interact with, connect with, all things, and is highly creative…but it’s not in the limited sense that most humans try to box “it” in as. It’s way more abstract and ineffable than can be grasped by most human minds. Actually trying to understand from an intellectual, hyper-analytical perspective, will often cause one not to “get” it. One can be very intellectual, yet needs to have the skill to table that too…and just be.
My professor confused the heck out of me. This video was very easy to understand and grasp. I never thought I would say this, but Harvard is saving my grade
This was a pleasure to watch. I’m not in school, just here for curiosity and I thoroughly enjoyed learning it because it was slow, simply explained, and illustrated so well. Thank you.
for anyone still struggling like I was, this is how i was able to kinda understand it; the purpose of the action potential is to allow neurotransmitters to release at the axon terminal/synapse. the wave of electrical charge travels all the way down and once it gets to where the neurotransmitter is stored in the vesicles near the synapse several things can happen but usually, there is a few more ion exchanges that end up with the vesicle membrane fusing with the cell membrane so that the neurotransmitter is floating around the OUTSIDE of the neuron. then the neurotransmitter can bind to the postsynaptic cell, open ligand-gated ion channels and create another action potential. and sometimes the neurotransmitter can bind to multiple cells my teacher doesn't care if we understand how it works, he just wants us to be able to parrot the steps of the sodium and potassium channels and the depolarization hyperpolarization and repolarization, and it was driving me crazy not knowing how this actually can help cells communicate with each other, so i hope this helps. i don't have full understanding yet or anything near it but i'm getting the vibe that information, thoughts, memories etc is more carried in the frequency, organization and order of which cells the nerve impulses go to
This is by far the best explanation on RUclips for the Hodkin-Huxley model. After watching it one, I understand everything about it. Amazing work, whoever made this. I'm sending you a virtual hug of appreciation ahaha
this is THE BEST action potential video out there!!! I've been struggling for ages and this video coverseverything in such a comprehensive and easy to understand manner. THANK YOU!
omg this is the best easiest way to understand this process, I got so much confused from the book and from my teacher!!! but here you are explaining so simple !!!! thank you so much, I finally got it on time for my exams, are in 2 days!! THANK YOU
I am having and exam in about 20 minutes. I was really worried, because I didn't understand the lecture but I found this video and it really helped me. English is not my first language so I was checking my notes as I was watching this and I understood everything. Great video. Thanks 😀
thank you so much. my teacher doesn't tell me shit and i was lost...then I found this video and all of my hope was restored. I love you even though i really hate action potential ur awesome of this i could cry I'm so happy. and I'm not even exaggerating
This is the best explanation in the entire world! I really understood the concept so well , i really wish all teachers would reach that level of understanding so they can explain to their students THIS WELL We are very lucky to have this video and i am very grateful, THANK YOU GOD الحمد لله
Dr Bashir on Star Trek DS9 just told Captain Sisko (acting as The Emissary for Baijors Prophets) that he needed to depolarize his neural sheaths... I hadn't a clue if that's possible or simply artistic license. Thank you Google for bringing me here. Actually I thank God for the internet daily- when i was young I'd have to visit the library to learn Anything... It oftentimes took many hours and sometimes days to gather all the pertinent resources to attain even just a passing familiarity with complicated processes, not to mention any esoteric topics. Lol Anyway. The instructor did a terrific job here explaining things so that even a dummy like me can understand. 🙂👍
This is fantastic, except for the part about the membrane potential being restored by the Na-K ATPase. One can poison that pump with ouabain, and it's a long time before action potentials begin to change shape or to fail. It's more useful to think of that active transporter as only charging the battery, and all of the voltage changes during an action potential coming about only from opening and closing of the voltage-gated channels.
This was the most helpful video is my high school week, the details are perfectly explained and opened my eyes to how beautiful the science world is. This helped me way more than my teacher could ever. Her explanation are so low and pea brained compared to this whole of art. Thank you so much -santanPwopa
thanks so much. I think Harvard is the best channel that can explained resting membrane potential process clearly with good animation. I have been searching video like this since yesterday. I get the AHA moment!
Great explanation video! I understood everything and what made it even better: You could feel the motivation of the teacher through the screen! She seemed ecstatic to be teaching! This really kept the video entertaining, as I was awaiting every next sentence. Monotonality? Don't know her!
This literally help me than those videos I have seen for action potentials and resting potential also the axon myelinated thing...... it's literally telling you all the basics which is why it's more understandable....very greatful for this video💯
Mam your voice is soothing and your English is very simple to hear. It helps me a lot. Please make these types of videos more. Thank you so much. 😊😊😊😊💓💓💓💓💓
Well, I could read over 100 pages of textbook and listen to 80 hours of lecture about this concept, or I could just watch this video and understand this like it was the easiest thing to learn in all my degree.... Thanks for the video! Sad that my professors never used it. :(
I have my first exam for Behavioral Neuroscience tomorrow covering a few different chapters, but I knew that the chapter on Graded Potentials and Action Potentials I would dread the most. Could never wrap my head around all the terminology in lecture. The textbook takes 5 pages to explain it. But sometimes it just takes 1 or 2 really well-made RUclips videos to not just understand something but actually enjoy it. I used to hate this subject so much but as soon as I saw the whole picture i was actually amazed at how awesome it was. Just think about all the energy you put into studying action potentials, your brain was repeatedly carrying out this exact same process just to teach itself and make sense of this process it’s already been doing!!!
THIS IS THE BEST EXPLAINATION ON HERE!! even better than Khan academy if you are studying for the MCAT or classes! It covered every detail in my 2019 -2020 Kaplan MCAT books! Thank you!
Excellent video, and one of the few to emphasise that the changes in ion concentration occur exclusively around the membrane, with the bulk of the cytoplasm and extracellular fluid remaining electrically neutral. Sometimes the opposite can be implied by media describing how conduction of action potentials is quicker in neurons with higher cross-sectional area. The latter is true, but is not down to cable theory as applied to electrical wires. Only a fraction of the neuron diameter sees changes in charge or ion content, as this video makes clear. It may be better for lecturers to highlight increased circumference rather than cross-section area as being responsible for faster conduction in larger neurons.
Thank you! I have been reading all my material supplied and my textbooks but have been struggling to get my head around this. Now I get it! Such a brilliant and clear video.
I liked this video, but I would have appreciated it more, if you also talked about chloride ions, since these are one way of how a neuron can be inhibited.
Anybody looking for notes? Cause this is what the aunty in the video said: Transmission of a neuronal signal Is entirely dependent on the movement of the ions Or charged particles. Various islands, including sodium, potassium and chloride Are unequally distributed between the inside and the outside of the cell. The presence and movement of these ions, Is not only important when a neuron fires but also at rest. To start let's think about the positively charged sodium and potassium ions. When a neuron is not sending a signal It is considered to be at rest. In a typical neuron in its resting state The concentration of sodium ion is higher Outside the cell Then in inside. The relative concentration of potassium ions Is the opposite with more ion's inside the cell than outside. This ionic separation occurs right at the cell membrane And creates a chemical gradient across the Membrane. Because ions are charged particle, we also need to consider Their charge when thinking about their distribution Across the membrane. At rest, there are more positively charged ions Outside the cell relative to the inside. This creates a difference in charge Across the membrane comma which is called an Electrical gradient. Together with chemical gradient we already mentioned We refer to this ionic imbalance As the electrochemical gradient. The difference in total charge inside and outside the cell is called as membrane potential. At rest when no signals are being transmitted Neuronal membrane has a resting potential Of approximately minus 70 M v. This means that the inside of the cell is approximately 70 millivoltes less positive than the outside. Both the chemical and electrical gradients, which are discussed contribute to a contribute to establishing this potential. While the inside of the cell has a net negative charge, the outside of the cell have a net positive charge, The charges line up at the membrane And the bulk solution on the either side Is actually electrically neutral. The resting membrane potential Is the point where the cell has achieved electrochemical equilibrium. This means that the concentration and the electro gradient for each ion is equal and Opposite. Ion's cannot simply move across the membrane at will. Instead, they need a protein embedded in the membrane To facilitate their movement. Most ion ones cross the membrane through a structure called as ion channel. Ions moved through channels by passive diffusion Along there concentration gradient. Some iron channels are always open, But many require signal to tell them to Open or close. For example voltage gated channels Only open when the membrane potential Reaches or certain value. On the other hand ligand gated ion channels Are triggered to open when they are bound by a specific molecule. Mechanically gated ion channels open In response to physical forces such as changes in length Or changes in pressure. Most ion channels are selectively permeable, meaning that they only allow one or a small subset of ions To pass through. Voltage gated ion channels, for example Typically only allow a single ion To cross the membrane when they open. This means that we need separate channels for each Ion That is Voltage gated sodium channels as well as Voltage gated potassium channels. As iOns move through a channel and cross from one side of the cell membrane to others They cause the membrane potential Off the cell to move away from its resting potential. If the resulting change in membrane potential is we call this a Graded potential. Graded potential can vary in sizes, can be either positive or negative, And typically do not result from the opening of voltage gated ion channel. When Ian channel opens and a credit potential occurs The neuron moves quickly to reset its membrane potential To resting values. This is primarily accomplished by the use of sodium Potassium pump which uses the energy Generated By a t p hydraulicies to actively transport ion Across the membrane against their concentration gradient. In other words the sodium is transported To the outside of the cell where its concentration is Higher and potassium is transported Into the cell where its concentration is higher. One cycle of this pump transports 3 sodium ions Outside the cell and brings two potassium ions inside the cell. This unbalanced charge transfer contributes To the separation of charge across the membrane And also to the ironic concentration we see at rest thus restoring the chemical and electrical gradients To their resting levels. Maintaining these ionic balance in neurons It's so important that it can account for twenty percent to forty percent of the brain's total energy use. Only when the resting membrane potential and iron distributions Are maintained at precise levels Will the neuron be poised and ready to fire an action potential. When the outside stimulation is large enough to bring the membrane potential in the neuron body up form -70mV to the threshold voltage if -55mV are higher, this triggers an action potential at the axon hillock, which then travels down the axon. Voltage-gated sodium channels have three states-- open, closed and inactivated. At rest, the sodium channel is closed. Once the cell membrane reaches the threshold voltage, The channel changes To an open position And sodium rushes into the cell because of the electrochemical gradient. As positive sodium ions enter the cell, The membrane potential becomes less negative and more positive As it approaches 0mV. This is called depolarization. Eventually the voltage gradient goes 0 and beyond 0 up to a +30mV. This is called an overshoot. As the membrane potential becomes +ve, the sodium channel inactivation gate shuts, making the channel inactivated. This stops the flow of sodium ions into the cell. The change in membrane potential also opens the voltage gated potassium channels, though they open and close more slowly. Because of potassium electrochemical gradient, potassium flow out of the cell, making it less positive and eventually negative. This process is called repolarization. Because the potassium channels are a little slow to close, for a brief period, the potential is hyperpolarized. It's more negative than the resting potential. During hyperpolarization the potassium channels close. Throughout all this the sodium Potassium pump is still working. The pump restores the chemical gradients by putting the sodium and potassium back in place. And the pump re establishes the potential gradient by moving more sodium ions out than potassium ions in. This returns the membrane potential back to its resting potential. During repolarization the inactivated sodium channels won't respond to any stimulus at all. During this time the neuron is in its absolute refactory Period and the period Of time when a nerve cannot fire another Action potential no matter how strongly it's stimulated. The absolute refractory period prevents action potentials from happening again To quickly and prevents action potential from travelling backwards along the axon. During hyperpolarization the sodium channels are closed and the inactivated gate opens. There is no change in sodium flow, but now they could be opened again. This is called the relative refractory period. Because while the sodium channels could open, it would take a larger than usual stimulus to reach threshold because the cell is hyperpolarized due to the potassium still leaving the cell. The amplitude of the action potential for a particular neuron, that is, the maximum voltage in one neuron During an action potential never changes. An action potential doesn't get bigger with a bigger stimulus. It's all or nothing. It either happens or doesn't happens. What can change is the frequency of the action potential. A neuron might fire many more times per second in response to, say, an intense pain and less frequently in response to a gentle breeze. Some axon transmit action potential faster than others. One variable that increases conduction velocity is the presence of myelin sheaths around axon. Myelin speeds up transmission through a process called Saltatory conduction, in which the action potential signal appears to jump along along the part of the axon covered by the sheath. In the peripheral nervous system, the sheaths are formed from glial cells known as Schwann cells. There are small gaps between Schwann cells called the nodes of ranvier. The action potential appears to jump from node to node, speeding the transmission. In the central nervous system, the sheaths are made by cells known as oligodendrocytes. With no stimulus the membrane is at its resting potential. A small stimulus causes a Graded potential. And an stimulus above the threshold creates and action potential and the neuron fires.
you literally just explained what takes up more than 10 pages of my textbook in a video that's shorter than 15 minutes. tysm!
Bnerbatt 😭
facts!!!
Yaa it's too short,but it is good for revision
This is one paragraph on my text book and she made It look like 10 pages. Shitty explanation
That’s what I’m saying. These textbooks just confuse ppl 😂. I always come to RUclips with these textbook topics
Every sentence is literally a ¨punchline¨. I wish schools around the world had the ability to convey the material that way, instead of confusing their students. well done harvard.
Honestly yes school books just throw in a bunch of unorganized data and they only give half of the information so they can confuse you even more
@@naglaakhaled5259 I’m currently in grad school and I feel that this statement is 100% correct. During courses, the professor/ textbook throws a bunch of information at you but you really only need the main points to succeed on tests/work outside of the classroom. Universities just need an excuse to keep students in the classroom longer and make them feel as if they ‘need’ all this information and need to pay for ridiculous tuition in order to be successful…
@@tinyr101 yet we’re learning the same stuff, arguably in a better format, on RUclips for free 🥴
@@Addison0526 YEP, and I still have to waste my time in a lecture room where I wont benefit from what the prof says 🐔
@@tinyr101 It would be wonderful if they turned that around - learned the main points- the bare bones first and THEN fill in all the details. It not only could save time but lets you organize information in a more logical manner. You'd retain alot more. Because throwing it all at you at once... It defeats the whole purpose. Memorizing words and phrases without understanding them is why kids forget half the stuff they needed just to pass a test.
I wish everyone well for the upcoming test!
You got this!
*Update: I'm now in college and I found myself coming back to this video since I have an exam tomorrow. Still extremely helpful!
Thank you very much🐼🐼 🌺🌺
Thank you! 🥺🙏🏻
Did you pass? :/
Thank you.
RUclips University!
This is by far the best explanation of action potentials I've ever come across. Thanks!
this 14 minute video should have been maybe 3 minutes. much better vids out there
@@JonLolattemove along then… not everyone learns the same way.
Also..condensing some things into less time isn’t always superior. Soemtimes concepts are missed.
It took me an hour to get through the whole video because I kept pausing it to get almost two pages of notes out of it. Thank you so much!
Do "Open Transcript" next time, and copy->Paste. :))
@@mbalensiefer wre s the transcript?
Me too
Lol I thought it was just me!
@@mbalensiefer "open transcript" is good, but it is sometimes *better* to write your own notes from what you're hearing, as doing so likely 'sets' the info into your brain better, I think.
Can I say that I went to Harvard after watching this video
Travis k yes! 👏 Be proud of yourself but remain humble - UofH Student :)
I think you should be allowed to
@Albert Darian you bitch stfu
@Howard Bishop it’s a scam m8 they steal all your information
Lmaoo
As a first year neuroscience student, my lectures on the introduction to this topic was covered over 3 hours and was very confusing to understand. This managed to keep the level of detail needed whilst keeping it simple and also under 15 mins... Thank you so much, this really helped.
Are you an undergrad student?
@@nrubab8222 yes
My professor couldn't make this make sense for the entire two semesters I had him. This one video explained it all to me in just 13:11. Thank you.
In my class they don't explain this stuff easily and non-complicated. This is like a dream, where all the complicated parts are filtered out and all the important things are here. Thank you Harvard this should be in all lectures and lessons about neurons
I wish my A and P teacher would just show this video. its so helpful
I’m on page 4 of notes! I can’t believe how much this video is helping me understand what I believe is going to be a large topic on my midterm for an SFSU psychology course titled “Perception.” I’ve been struggling to conceptualize brain structures and brain activity that is now included in my courses. I’ve never seen any of it before and have had to slowly teach myself through videos like this when, even after re-reading the dense textbook, I still struggle to keep it all clear. As a very passionate psych undergrad who has never had to take chemistry or any class past intermediate biology, this video made me feel like I really missed out on appreciating science classes more because now that it was explained in a way I can understand, it blew my freakin mind. God I love learning.
If anyone is wondering, there are things called leaky K+ gates that always allow a little bit of K+ ion movement across the membrane. This is how the resting potential is restored after hyperpolarisation (when it goes to negative). Because it's so negative inside the cell (below the resting potential of -70mV) K+ ions will move into the cell because of the electrical gradient, sodium ions can't their gates are shut. This movement of K+ ions into the cell makes it more positive and restores the resting potential. The sodium potassium ion pumps do help a little to maintain the electrical gradient, but mostly they keep the chemical gradient (Na+ in high concentration outside, K+ high conc. inside) with the leaky K+ (how many / how leaky they are) determining the electrical gradient and therefore the resting potential.
EDIT: As pointed out to below there are leaky sodium gate to there are just more leaky potassium gates so the over all movement of ions = more K+ ions move than Na+ ions, but the effect is the same, there is a net movement of K+ ions into the cell.
Or as below:
"I think there are sodium leak channels as well. Sodium is constantly leaking into the neuron to make the membrane potential less negative. This is why there is the Na+ K+ pump to establish the -70mV potential, because without it the Na+ and K+ will just leak according to their electrochemical gradient. However, during hyperpolarization, the electrochemical gradient is so large that the leaks are leaking ions faster than the pumps, that is why the membrane potential can go back to -70mV. Sodium leaks and potassium leaks should be different though. Sodium leaks are protein channels but potassium leaks are holes in the membrane. "
Sorry, can you explain this better? I am not understanding how the potential is restored again after hyperpolarization. If 3 sodiums and 2 potassiums pass through, wouldn't the cell be losing 1 negative ion all the time, making it even more negative?
@@booyah9402 losing a net of one positive ion and making it more negative yes. The K+ gates "leak" a little bit. These gates are not the ion channels pumping the 3Na+ / 2K+, they are gates not channels. They stop most the K+ ions moving when shut, but a few still get past even when shut. When the cell becomes very negative on the inside the electrical difference (the potential difference across the cell membrane) is large enough so K+ ions are forced back into the cell through the K+ ion channels. This is moving from low conc. of K+ ions on the outside to high on the inside, so is moving against the concentration gradient and how diffusion would work, but the electrical difference is so big it pushes positive K+ ions into the cell to restore the electrical gradient. NA+ ions can not be pushed into the cell as their gates do not "leak".
Did that help?
@@booyah9402actually 3 factors contribute to RMP:
1.Na+/k+ pumps.
2.leaky k+ channels
3.leaky Na+ channels
U must know permeability of k+ is much more than Na+ because of the presence of large amount of k+ channels than Na+ channels on membrane (approx. In the ratio of 100:1)
As a result the cell membranes is significantly more permeable to k+ than to Na+.
In that case you can consider, more sodium ion enter the cell during depolarization than potassium ions that goes out during repolarization. @@booyah9402
Thank you. I was confused by the last part of the video where it says pumping 3 sodium out and 2 potassium in restores the cell from hyperpolarized state to resting potential. I think that last part is a bit misleading since the pump always makes the cell more negative.
this 13 min video covered this content way better than my professor's 40 minute video
as a homeschooled kid making my own cutriculum, thank you for this resource. i learned about ion channels the other day and was like “wtf those things do” then was looking into the specific cell functions of neurons and thwy came up bigtime. everything is connected
great video, i understand why Harvard students are so smart, if your explanations are this good online, I cannot imagine how great the lecture are in person.
I am 14 and obsessed with a level psychology: This video was very useful, particularly for clarification and being clear and concise!
For anybody confused:
Basically the dendrites are decorated with synapses, which don't quite touch the next axel, but have literally less than 1 millionth of an inch between them. The dendrites decide whether to pass the stimulation on, and if yes, then the process begins. The stimulation is passed through the cell membrane (soma), through the axel (which is often covered in a layer of protective fat called the myelin sheath) where the action potential then reaches the axel terminal, and the action potential "jumps" across the synaptic gap and into there receptor sites (like a key fitting into a lock).
so smart for a 14 year old! keep it up!
@@jem3706 he reads, american teenagers don't read
I was so baffled by the Neuroscience introductory class. This video made me understand the process so easily. More videos on topics like this are appreciated. Thank you...
I can't thank you enough for this video. I am a big visual learner and this should be presented in all physiology classes. Wow!
4 years later and still saving lives
It all finally makes sense! This video is brilliant in its simplicity and cuts out all the fluff that made it complicated!
A complex phenomenon explained in ease. Slow steady and clear explanation with beautiful animation which we can actually visualise. Thanks a ton for making the learning so simple.
This is a FANTASTIC EXPLANATION! It includes so many helpful details that are simply not covered in other videos about this subject. Thank you so much!
Can I conmect with you plazzz
Literally my teacher explained this concept in the worst way possible 😐 thanks to this video
This is simplest vedio on Action potential....very helpful in clearing my physiology exam
Big thank you to Ethan Contini-Field, Dr. Jennifer Carr, and Michael Davis for putting together such a wonderfully helpful video. Good job!
When did we start listing names alphabetically by FIRST NAME instead of last name? 🤨
Still amazes me that this universe developed such a complex organization of matter
Universe > super power > creator >✨ God ✨
🥰 That's the one and only Truth to explain these amazing super complex operations .
@@نورالإيمان-ع8ذ why does the universe have to be created? If it was created what created the creator? If the creator could be deemed eternal, why couldn’t this universe simply be eternal?
Alien overlords 👽👑
@@Geminish15 if that’s so, how did they develop? Must be just as fascinating
@@F8LDragon2I think it is a circular expanding energy…not some “god” in the sky like many religions made.
Because of so many dogmatic ideologies, often used to control and suppress people (and yes, in some cases to try to explain the unexplainable)…to often people are entirely turned off by the idea of a greater force, especially when paired with the name of “god”. That word, label, is so loaded.
I do believe there is creative force, that does interact with, connect with, all things, and is highly creative…but it’s not in the limited sense that most humans try to box “it” in as. It’s way more abstract and ineffable than can be grasped by most human minds. Actually trying to understand from an intellectual, hyper-analytical perspective, will often cause one not to “get” it.
One can be very intellectual, yet needs to have the skill to table that too…and just be.
My professor confused the heck out of me. This video was very easy to understand and grasp. I never thought I would say this, but Harvard is saving my grade
this 13 min video covers four of my lectures...
lmao
It covers 2 minutes of mine! That’s why I needed this
It's about 1/4 of my first lecture for the course...
Sam, check out the crash course video. Each sentence is packed with info
same
This was a pleasure to watch. I’m not in school, just here for curiosity and I thoroughly enjoyed learning it because it was slow, simply explained, and illustrated so well. Thank you.
I'm not in school now either. Interesting how much more i enjoy learning when i do it just for fun.
for anyone still struggling like I was, this is how i was able to kinda understand it;
the purpose of the action potential is to allow neurotransmitters to release at the axon terminal/synapse. the wave of electrical charge travels all the way down and once it gets to where the neurotransmitter is stored in the vesicles near the synapse several things can happen but usually, there is a few more ion exchanges that end up with the vesicle membrane fusing with the cell membrane so that the neurotransmitter is floating around the OUTSIDE of the neuron. then the neurotransmitter can bind to the postsynaptic cell, open ligand-gated ion channels and create another action potential. and sometimes the neurotransmitter can bind to multiple cells
my teacher doesn't care if we understand how it works, he just wants us to be able to parrot the steps of the sodium and potassium channels and the depolarization hyperpolarization and repolarization, and it was driving me crazy not knowing how this actually can help cells communicate with each other, so i hope this helps. i don't have full understanding yet or anything near it but i'm getting the vibe that information, thoughts, memories etc is more carried in the frequency, organization and order of which cells the nerve impulses go to
This is lit you made the concept so easy 😅😅 saved from reading 15 slides
This is by far the best explanation on RUclips for the Hodkin-Huxley model. After watching it one, I understand everything about it. Amazing work, whoever made this. I'm sending you a virtual hug of appreciation ahaha
Make the video x1.25, then it becomes normal
😂
True 😂
Absolutely clear, each sentence is an important aspect, amazing job harvard
This explanation with the graphics is super good. It definitely helped me learned my class material better. Thank you Harvard.
this is THE BEST action potential video out there!!! I've been struggling for ages and this video coverseverything in such a comprehensive and easy to understand manner. THANK YOU!
Okay...this was just about the best narration I needed to understand the concept. Just on point.
Thank you for making your work available to all. I really enjoy your excellent presentations.
omg this is the best easiest way to understand this process, I got so much confused from the book and from my teacher!!! but here you are explaining so simple !!!! thank you so much, I finally got it on time for my exams, are in 2 days!! THANK YOU
I am having and exam in about 20 minutes. I was really worried, because I didn't understand the lecture but I found this video and it really helped me. English is not my first language so I was checking my notes as I was watching this and I understood everything. Great video. Thanks 😀
Magnificent, it can't get better than this. Thank you Harvard.
ayo....there is a reason why you mans are the top UNi still.
Respect G
Thank you so much... ❤ this was very informative
The explanation was so clear...ive understand it most compared to the other videos ive tried watching
Thank you so much! This video is just what I need, it’s clear and to the point.
thank you so much. my teacher doesn't tell me shit and i was lost...then I found this video and all of my hope was restored. I love you even though i really hate action potential ur awesome of this i could cry I'm so happy. and I'm not even exaggerating
Wow this video made me understand my lecture college
This is the best explanation in the entire world! I really understood the concept so well , i really wish all teachers would reach that level of understanding so they can explain to their students THIS WELL
We are very lucky to have this video and i am very grateful, THANK YOU GOD الحمد لله
Dr Bashir on Star Trek DS9 just told Captain Sisko (acting as The Emissary for Baijors Prophets) that he needed to depolarize his neural sheaths... I hadn't a clue if that's possible or simply artistic license. Thank you Google for bringing me here. Actually I thank God for the internet daily- when i was young I'd have to visit the library to learn Anything... It oftentimes took many hours and sometimes days to gather all the pertinent resources to attain even just a passing familiarity with complicated processes, not to mention any esoteric topics. Lol
Anyway. The instructor did a terrific job here explaining things so that even a dummy like me can understand. 🙂👍
Freaking love everyone who contributed to this gem of a video LOVE YALL
this shows how important/easy it is to learn something from a visual standpoint than just reading from the book
I'm gonna cry I still don't get it
Try to watch other videos,the more sources and different explanations the more u get jt
@@nouraattia452 thanks but now ive mastered it
@@kristina6406can you help me 😢
If you did wouldn't that mean you understand what consciousness is? I don't get it either.
this vid gave me potential to do some serious note-taking action
Haha
I always come to this video whenever I need to revise my concepts. This video is packed with valuable information!
This video removed my complexities simply. Loved the way it made me understand the whole fact.
This is fantastic, except for the part about the membrane potential being restored by the Na-K ATPase. One can poison that pump with ouabain, and it's a long time before action potentials begin to change shape or to fail. It's more useful to think of that active transporter as only charging the battery, and all of the voltage changes during an action potential coming about only from opening and closing of the voltage-gated channels.
mind blown i've been struggling with this concept all semester and it was explained in less than 15 minutes
This was the most helpful video is my high school week, the details are perfectly explained and opened my eyes to how beautiful the science world is. This helped me way more than my teacher could ever. Her explanation are so low and pea brained compared to this whole of art. Thank you so much
-santanPwopa
That makes sooo much sense! Thank you! I appreciate that you connected the action potential back to the myelin sheath, it makes sense.
thanks so much. I think Harvard is the best channel that can explained resting membrane potential process clearly with good animation. I have been searching video like this since yesterday. I get the AHA moment!
Great explanation video! I understood everything and what made it even better: You could feel the motivation of the teacher through the screen! She seemed ecstatic to be teaching! This really kept the video entertaining, as I was awaiting every next sentence. Monotonality? Don't know her!
Thank you so much for this. Helped my study. Psy 221 exam tomorrow!!!! wish me luck!
Sike!
So helpful ,this is my second time watching and revising AP
This literally help me than those videos I have seen for action potentials and resting potential also the axon myelinated thing...... it's literally telling you all the basics which is why it's more understandable....very greatful for this video💯
Mam your voice is soothing and your English is very simple to hear. It helps me a lot. Please make these types of videos more. Thank you so much. 😊😊😊😊💓💓💓💓💓
Well, I could read over 100 pages of textbook and listen to 80 hours of lecture about this concept, or I could just watch this video and understand this like it was the easiest thing to learn in all my degree.... Thanks for the video! Sad that my professors never used it. :(
Ridiculously clear and helpful! I'm using it to develop content for "neurobiology and addiction" presentations. Thank you!!
I have my first exam for Behavioral Neuroscience tomorrow covering a few different chapters, but I knew that the chapter on Graded Potentials and Action Potentials I would dread the most. Could never wrap my head around all the terminology in lecture. The textbook takes 5 pages to explain it. But sometimes it just takes 1 or 2 really well-made RUclips videos to not just understand something but actually enjoy it. I used to hate this subject so much but as soon as I saw the whole picture i was actually amazed at how awesome it was. Just think about all the energy you put into studying action potentials, your brain was repeatedly carrying out this exact same process just to teach itself and make sense of this process it’s already been doing!!!
Your briefly explanation have cleared my mind satisfactorily
THIS IS THE BEST EXPLAINATION ON HERE!! even better than Khan academy if you are studying for the MCAT or classes! It covered every detail in my 2019 -2020 Kaplan MCAT books! Thank you!
I have an exam tomorrow and this has helped tons!! Thank you!
Excellent Video! Thank you for speaking slowly and clearly. Very helpful!
very helpful! Covers like 30 slides of my professors powerpoint in a very clear, understandable way!
Such a brilliant, clear explanation with great animation. Huge help. Thank you
You have really made me understand what this topic entails..... Im totally speechless after listening to the video
Excellent video, and one of the few to emphasise that the changes in ion concentration occur exclusively around the membrane, with the bulk of the cytoplasm and extracellular fluid remaining electrically neutral. Sometimes the opposite can be implied by media describing how conduction of action potentials is quicker in neurons with higher cross-sectional area. The latter is true, but is not down to cable theory as applied to electrical wires. Only a fraction of the neuron diameter sees changes in charge or ion content, as this video makes clear. It may be better for lecturers to highlight increased circumference rather than cross-section area as being responsible for faster conduction in larger neurons.
Great animation by Michael Davis the animation designer.
i was astonished by the way they presented this video.Hats off!!!!!!!
My teacher in allen used this video in class this video was so helpful 🎉🎉
video makes this much more easier to digest. thanks harvard
Excellent! I have the idea but will have to listen several more times. Thank you so much.
video is so good, my teacher used it.
Thank you! I have been reading all my material supplied and my textbooks but have been struggling to get my head around this. Now I get it! Such a brilliant and clear video.
Use mnemonic NOKIA- Na2+ out (the cell) K+ in (the cell).
This is for the sodium potassium pump.
Excellent explanation which included plenty of detail. Thank you.
This is so good! This is our assignment for Anes
Great information, great animations, and a great narrator, thanks a lot
Simple video! Perfect for you to have an idea about the subject before diving into it! Thank you!
Great video for MCAT prep!!!!!
Fantastic Explanation. Wonderful diagrams used.
easy to understand, love this video! thank you for the explanations :)
Finally a video with some content! Extension School? For an extended career? Of for extended knowledge? Watch the playlists and you know.
this video well explanied everything i did study on cell biology and i wasnot sure about certain points i really wish you all best harvard
Appreciable work please provide more such material to help us study
Thanks a lot
Now I see what does the true power of Harvard looks like...
I liked this video, but I would have appreciated it more, if you also talked about chloride ions, since these are one way of how a neuron can be inhibited.
this makes it so easy for a topic that seemed so complex!!!!! thank you ;-----;
EXCELLENT GIVE DR CARR A NOBEL PRIZE FOR EXPLAINING SO WELL
Anybody looking for notes? Cause this is what the aunty in the video said:
Transmission of a neuronal signal Is entirely dependent on the movement of the ions Or charged particles. Various islands, including sodium, potassium and chloride Are unequally distributed between the inside and the outside of the cell. The presence and movement of these ions, Is not only important when a neuron fires but also at rest.
To start let's think about the positively charged sodium and potassium ions. When a neuron is not sending a signal It is considered to be at rest. In a typical neuron in its resting state The concentration of sodium ion is higher Outside the cell Then in inside. The relative concentration of potassium ions Is the opposite with more ion's inside the cell than outside. This ionic separation occurs right at the cell membrane And creates a chemical gradient across the Membrane.
Because ions are charged particle, we also need to consider Their charge when thinking about their distribution Across the membrane. At rest, there are more positively charged ions Outside the cell relative to the inside. This creates a difference in charge Across the membrane comma which is called an Electrical gradient. Together with chemical gradient we already mentioned We refer to this ionic imbalance As the electrochemical gradient.
The difference in total charge inside and outside the cell is called as membrane potential. At rest when no signals are being transmitted Neuronal membrane has a resting potential Of approximately minus 70 M v. This means that the inside of the cell is approximately 70 millivoltes less positive than the outside. Both the chemical and electrical gradients, which are discussed contribute to a contribute to establishing this potential. While the inside of the cell has a net negative charge, the outside of the cell have a net positive charge, The charges line up at the membrane And the bulk solution on the either side Is actually electrically neutral. The resting membrane potential Is the point where the cell has achieved electrochemical equilibrium. This means that the concentration and the electro gradient for each ion is equal and Opposite.
Ion's cannot simply move across the membrane at will. Instead, they need a protein embedded in the membrane To facilitate their movement. Most ion ones cross the membrane through a structure called as ion channel. Ions moved through channels by passive diffusion Along there concentration gradient. Some iron channels are always open, But many require signal to tell them to Open or close. For example voltage gated channels Only open when the membrane potential Reaches or certain value. On the other hand ligand gated ion channels Are triggered to open when they are bound by a specific molecule. Mechanically gated ion channels open In response to physical forces such as changes in length Or changes in pressure. Most ion channels are selectively permeable, meaning that they only allow one or a small subset of ions To pass through. Voltage gated ion channels, for example Typically only allow a single ion To cross the membrane when they open. This means that we need separate channels for each Ion That is Voltage gated sodium channels as well as Voltage gated potassium channels.
As iOns move through a channel and cross from one side of the cell membrane to others They cause the membrane potential Off the cell to move away from its resting potential. If the resulting change in membrane potential is we call this a Graded potential. Graded potential can vary in sizes, can be either positive or negative, And typically do not result from the opening of voltage gated ion channel. When Ian channel opens and a credit potential occurs The neuron moves quickly to reset its membrane potential To resting values. This is primarily accomplished by the use of sodium Potassium pump which uses the energy Generated By a t p hydraulicies to actively transport ion Across the membrane against their concentration gradient.
In other words the sodium is transported To the outside of the cell where its concentration is Higher and potassium is transported Into the cell where its concentration is higher. One cycle of this pump transports 3 sodium ions
Outside the cell and brings two potassium ions inside the cell. This unbalanced charge transfer contributes To the separation of charge across the membrane And also to the ironic concentration we see at rest thus restoring the chemical and electrical gradients To their resting levels. Maintaining these ionic balance in neurons It's so important that it can account for twenty percent to forty percent of the brain's total energy use. Only when the resting membrane potential and iron distributions Are maintained at precise levels Will the neuron be poised and ready to fire an action potential.
When the outside stimulation is large enough to bring the membrane potential in the neuron body up form -70mV to the threshold voltage if -55mV are higher, this triggers an action potential at the axon hillock, which then travels down the axon.
Voltage-gated sodium channels have three states-- open, closed and inactivated. At rest, the sodium channel is closed. Once the cell membrane reaches the threshold voltage, The channel changes To an open position And sodium rushes into the cell because of the electrochemical gradient. As positive sodium ions enter the cell, The membrane potential becomes less negative and more positive As it approaches 0mV. This is called depolarization.
Eventually the voltage gradient goes 0 and beyond 0 up to a +30mV. This is called an overshoot.
As the membrane potential becomes +ve, the sodium channel inactivation gate shuts, making the channel inactivated. This stops the flow of sodium ions into the cell. The change in membrane potential also opens the voltage gated potassium channels, though they open and close more slowly. Because of potassium electrochemical gradient, potassium flow out of the cell, making it less positive and eventually negative. This process is called repolarization.
Because the potassium channels are a little slow to close, for a brief period, the potential is hyperpolarized. It's more negative than the resting potential. During hyperpolarization the potassium channels close. Throughout all this the sodium Potassium pump is still working. The pump restores the chemical gradients by putting the sodium and potassium back in place. And the pump re establishes the potential gradient by moving more sodium ions out than potassium ions in. This returns the membrane potential back to its resting potential.
During repolarization the inactivated sodium channels won't respond to any stimulus at all. During this time the neuron is in its absolute refactory Period and the period Of time when a nerve cannot fire another Action potential no matter how strongly it's stimulated. The absolute refractory period prevents action potentials from happening again To quickly and prevents action potential from travelling backwards along the axon. During hyperpolarization the sodium channels are closed and the inactivated gate opens. There is no change in sodium flow, but now they could be opened again. This is called the relative refractory period. Because while the sodium channels could open, it would take a larger than usual stimulus to reach threshold because the cell is hyperpolarized due to the potassium still leaving the cell.
The amplitude of the action potential for a particular neuron, that is, the maximum voltage in one neuron During an action potential never changes. An action potential doesn't get bigger with a bigger stimulus. It's all or nothing. It either happens or doesn't happens. What can change is the frequency of the action potential. A neuron might fire many more times per second in response to, say, an intense pain and less frequently in response to a gentle breeze.
Some axon transmit action potential faster than others. One variable that increases conduction velocity is the presence of myelin sheaths around axon. Myelin speeds up transmission through a process called Saltatory conduction, in which the action potential signal appears to jump along along the part of the axon covered by the sheath.
In the peripheral nervous system, the sheaths are formed from glial cells known as Schwann cells. There are small gaps between Schwann cells called the nodes of ranvier. The action potential appears to jump from node to node, speeding the transmission.
In the central nervous system, the sheaths are made by cells known as oligodendrocytes.
With no stimulus the membrane is at its resting potential.
A small stimulus causes a Graded potential.
And an stimulus above the threshold creates and action potential and the neuron fires.
This video is very beneficial for students ...... Tnx alot Harvard