Action Potential - Firing of a Neuron - Depolarization

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In this video, Dr. Kushner breaks down an action potential, a brief electrical charge that travels down the axon of a neuron. Consider the different phases to this amazing event:
1. Depolarization (sodium channels open - Na+ rushes in - neuron become more positive - generates an action potential - +30 mV)
2. Repolarization (sodium channels close; potassium channels open - K+ rushes out; neuron rebalances voltage)
3. Hyperpolarization/Refractory period (neuron recharges; -90 mV)
5. Resting potential/state (neuron returns to -70 mV)

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[@PsychExplained]

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🧂🍌 Na+ K+ ATPase love your videos ❤ Dr. Kushner 🥼👩🏽‍🔬 this was so easy to understand because you draw it and break it down. Great graphics Salty Banana 🧂🍌 pouring salt all over the banana and remember -70 to +55 then resting

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[@PsychExplained]

Happy to help 🤓

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This video is life-changing 😊! Thanks so much for the detailed drawing and steps!

[@PsychExplained]

So happy to help!

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[@PsychExplained]

Appreciate the kind words! It may surprise you but I teach high school AP Psychology. These videos are for you, and helping you earn that 5! Many more to come.

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[@factuna6694]

Thank you for the very well put explanation. The only thing, however, you didn't mention was the sodium-potassium pump, which is what allows the neuron to return to the resting stage after being hyperpolarized!

[@PsychExplained]

Wonderful! Great pick up

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I'm a first year uni student and I've been looking for videos explaining this concept. This was perfect and really easy to grasp, you just gained a new subscriber. thank you

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Amazing Teacher, honestly not only did I learn more about Neurons but I also learned how to teach in a more clear fashion by watching how you explain things

[@PsychExplained]

Thank you so much for your kind words!

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The best video i have seen so far on action potential thank you so much.

[@PsychExplained]

Too kind. Glad it helped 🧠

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wow I was so confused on action potential and you made it so clear and understanding without using so much terminology! Thank you!!!!!!!!!!!

[@PsychExplained]

You're very welcome!

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That’s so great to hear! Happy to help 😊

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[@PsychExplained]

Love the pun!! Good luck 👍

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This is THE best explanation I've seen of this concept on youtube omg

[@PsychExplained]

Thank you 😊

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Your energy is everything and so are your teaching skills! God bless you! Thanks a lot. Doing my nursing degree and needed to understand this well!! Everything you said helped a lot🙏🏾💕

[@PsychExplained]

Wonderful! Nurses are amazing. Enjoy the journey :)

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Thank you for explaining it to me in simple and understandable way

[@PsychExplained]

Glad it was helpful!

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Fantastique! = +-+-+-+-+-+- ... I recently learned that due to a violent upbringing I have premature myelination and four other premature stuff that went on at a microscopic level within me. I was left with axons looking as if they were pumped up on steroids due to development adaptation. This vid has just given the nitty gritty to my external potential. Look out bad world, the Hulk lives. THANK YOU Doc.

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[@PsychExplained]

Happy to help! 😎😎

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You are teaching me also English! Keep going men. Please more on statistics (null hypothesis, regressions) and physiology (muscle function, muscle damage).

[@PsychExplained]

More to come!

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Thank you very much, this is the best video and I now understand the action potential

[@PsychExplained]

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[@PsychExplained]

Glad it helped!

[@peipewde6988]

thankx finally somone explained what cause the hypopolarization .

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Your video in 1.25 speed was the best explanation of this process! Thank you

[@PsychExplained]

Glad it was helpful!

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[@PsychExplained]

Glad it was helpful!

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Fantastic explanation!

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Love love love your explanations! Thankyou

[@PsychExplained]

You are so welcome!

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[@PsychExplained]

Wonderful! Thank you for the kind words. Happy learning 🧠 📚 ✏️

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[@PsychExplained]

Thank you for the support!

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@@daisymarquez7668 check out Siebert Science! He has great videos on these topics.

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[@ifranadeem]

Whatt a great explanation finally i understand action potential just one question that in the end after hyperpolarisation do the sodium ions also go back out of the neuron??

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[@pawloiox2585]

So, the transmission of the action potential is like an electric canon

[@newmoonrain]

Why is the voltage at -70 inside at the start? If potassium is positive, what else is in the neuron that's so negative? Great video btw, thank you!

[@PsychExplained]

The resting membrane potential of approximately -70 millivolts (mV) inside a neuron at rest is primarily due to the differential distribution of ions across the cell membrane, particularly potassium (K+) and sodium (Na+), as well as the selective permeability of the membrane to these ions.

[@terry-annhall2704]

Sir yor explanation of the action potential was very good, but you did not explain how the amount of sodium on the outside and potassium on the inside return to normal.

[@PsychExplained]

Repolarization - brings the cell back to resting potential. The inactivation gates of the sodium channels close, stopping the inward rush of positive ions. At the same time, the potassium channels open.

[@user-iz3oe6zn5j]

you teach in a brilliant manner :] ...but i have a question when the potassium ions move out and the neuron comes to a polarised state how does it fire again ? how does the potassium ion re-enter or are present in the neuron nd its at negative 70 again ?

[@chancelira6302]

DR.KUSH

[@sirbucket3202]

these sodium ions are going in and out of the neurons so fast is this Tom and Jerry or something😭

[@shariqanida9492]

🎯 Key Takeaways for quick navigation: 00:31 *🧠 Understanding Action Potential* - Action potential defined as a brief electrical charge traveling down a neuron. - Neuron anatomy overview: soma, dendrites, axon, axon terminal. - Importance of action potential in neuron communication. 02:23 *🧪 Ion Concentration and Neuronal Resting State* - Neurons surrounded by ions: sodium and potassium. - Resting potential of a neuron at -70 millivolts. - Explanation of the "salty banana" memory technique. 04:01 *⚡️ Excitation and Binding of Neurotransmitters* - Excitation of neurons by stimuli like neurotransmitters. - Role of acetylcholine in binding to receptor sites on dendrites. - Opening of channels for sodium influx upon binding. 06:05 *🎇 Threshold and Action Potential Initiation* - Explanation of the neuron's firing threshold at -55 millivolts. - All-or-none principle: neuron fires when threshold reached. - Activation of voltage-gated sodium channels for action potential initiation. 07:54 *🔥 Depolarization Phase* - Depolarization: neuron becoming more positive. - Sodium influx leading to increased positivity inside the neuron. - Voltage change triggers the action potential. 10:04 *⏳ Repolarization and Hyperpolarization* - Repolarization phase: closure of sodium channels, opening of potassium channels. - Potassium efflux causing the neuron to return to negative polarity. - Hyperpolarization and refractory period before returning to resting potential. Made with HARPA AI

[@faba-carter3996]

Cool

[@emaaneemaane7emaaneemaane7]

Sir you explained really well but Kindly tell me why chloride ions didn't play that much role in action potential though they are also present in this process? kindly Explain.

[@PsychExplained]

They play a major role at the synaptic bulb (axon terminal). I will touch on this more in my next video on neural transmission ⚡️⚡️⚡️⚡️⚡️

[@fazelahmad7320]

Thanks, good explination! But what happens afterward because this time all the K+ is outside and Na+ is inside. The normal position was the opposite (K+ were inside and Na+ were outside).

[@jk9-fr6xm]

asking the same question

[@PsychExplained]

Potassium channels open in response to depolarization, allowing potassium ions to move out of the cell down their concentration gradient. This efflux of potassium ions helps restore the negative charge inside the cell. Sodium channels that opened during depolarization begin to close, reducing the influx of sodium ions into the cell. This decreases the positive charge inside the cell. As a result of these processes, the ion gradients across the cell membrane gradually return to their resting state, with potassium ions predominantly inside the cell and sodium ions predominantly outside. This restoration of ion gradients allows the neuron to prepare for subsequent action potentials and maintain its resting membrane potential.

[@user-dh8ci9ue5w]

And how does the potassium come back in and the sodium leave to go back to original resting potential? That bit wasn't mentioned. It sounds like in the end, the charge might be the same, but with hardly any K+ And lots of Na+ compared to first charge

[@PsychExplained]

While the sodium-potassium pump helps restore the original ion concentrations, other mechanisms, such as the closing of voltage-gated sodium channels and the opening of potassium leak channels, also contribute to reestablishing the resting membrane potential.

[@SanKosar2005]

Is the Refractory period part of the repolorization?

[@PsychExplained]

Great question. I would say no. These are separate events. Order: Resting state --depolarization-Repolarization --hyperpolarization (refractory period). Repolarization is part of the firing process of a neuron, while the refractory period deals with a neurons ability to generate another action potential.

[@Nadavsolution]

How don't we have only Na+ inside after several times the nerve is in action? Should be nun out of K+ and only have Na+ left inside the neurone??