Great video, thank you. You were the only video to differentiate between Leak channels and voltage-gated potassium channels, and that's just the explanation I was looking for!
Correction - When potassium channel's open during the action potential, it is called repolarization, and then we get hyper polarization after this during the refractory period.
If I pass any of my physiology exams it's not gonna be thanks to my professor but to the khan academy (the same is true for all of my classmates). Thank you so much!!
I was taught that the equilibrium potential for Sodium is actual around +60 mV, and the resting potential is usually around -70 mV, and that threshold is about -50 mV.
Indeed, different neurons and other excitable cells (like those in skeletal and cardiac muscle) have different values depending on the exact ion concentrations inside and outside the cll. There may be species differences too. Whether you quote -60mV or -70mV for the resting potential is less important than understanding how it is generated and maintained.
Well, interesting but it seems that at the end of the action potential the axon is full of Na+. It has to flow out maybe by the Na+/K+ pump not mentioned here?
Actually, the number of Na+ ions that have to cross the membrane to depolarize it is relatively small - so small that the concentration of ions hardly changes in larger neurons. That means the number of ions that exit for repolarization is also small. You may hear people say "sodium floods in" during an action potential, but that is a bit misleading because it implies large changes in ion concentrations, and that all that "flood" has to be pumped out again, which isn't the case. A good analogy would be to say a neuron is like a rechargeable battery. You can get a flashlight to come on many times on one battery charge. Likewise a neuron can support many action potentials firing before ion concentration gradients run down. The larger the neuron, the more APs can fire. The Na+/K+ pump is like a trickle-charger that keeps the neuron's "battery" topped up. It isn't needed for AP firing in the short term, but is useful to maintain normal function over time. Hope this clarifies things for you!
Are sodium channels ligand-gated or voltage-gated or both? I think initial action potential is triggered by influx of sodium ions through ligand-gated channels activated by binding of acetylcholine. Thereafter, the action potential is propagated through the entire length of the axon by influx of more sodium through voltage-gated channels.
Sorry, there are more subtitle errors that I took the liberty of listing: 3:55, 4:24, 4:28, 4:42, 5:06, 5:11, 5:43, 5:54, 5:56, 7:01, 7:33, 7:36, 7:41, 7:48, 8:09, 8:36, 8:59 and 9:16, "ação potencial" instead of "potencial de ação". 9:06 "ações potenciais" instead of "potencias de ação". 1:03, 1:15, 3:08, 4:21, 4:26, 5:08, 5:30, 6:55, 8:28 and 8:48 "membrana potencial" instead of "potencial de membrana". Seems like every use of those terms is wrong, should be pretty easy to fix.
what is the range of absolute refractory period? does it extend til the lowest point of hyperpolarisation or it stops at the point AP has fallen til the resting potential?
is the trigger zone of the axon you're talking about at 1:40 the axon hillock? or is the axon hillock just for summation of input and then this process you talk about happens after the axon hillock? thanks, great video :)
The "trigger zone" is wherever in the axon hillock the AP is started. It's not an actual anatomical structure, but it is usually in the axon hillock so it's pretty much interchangeable
Hi, i have a question... i though the absolut period happen since the excitatory stimulus cross the treshold until the end of the repolaritation state, but according to the video all the periods occurs during the hiperpolaritation state, then i got confused about it.. can someone take this over ? i will be waiting the answer!
Someone should give you guys a golden medal or something, really your just AMAZING
Thanks alot !
This, and the whole "Neuron membrane potentials"-playlist was very helpful! Thanks alot!
Great video, thank you. You were the only video to differentiate between Leak channels and voltage-gated potassium channels, and that's just the explanation I was looking for!
Correction - When potassium channel's open during the action potential, it is called repolarization, and then we get hyper polarization after this during the refractory period.
Your reply should be pinned at the top. Thanks for clarifying the video
i really like how you draw the arrows in your videos. so satisfying by its oscillation
If I pass any of my physiology exams it's not gonna be thanks to my professor but to the khan academy (the same is true for all of my classmates).
Thank you so much!!
For 90% of students
THIS IS THE BEST VIDEO FOR NEURON AP ON THE INTERNET
this is so easy to understand.. thank you so much😭😭
I was taught that the equilibrium potential for Sodium is actual around +60 mV, and the resting potential is usually around -70 mV, and that threshold is about -50 mV.
Different books have different values. I was taught threshold potential as -55, spike potential as +45 and resting potential as -70
Indeed, different neurons and other excitable cells (like those in skeletal and cardiac muscle) have different values depending on the exact ion concentrations inside and outside the cll. There may be species differences too. Whether you quote -60mV or -70mV for the resting potential is less important than understanding how it is generated and maintained.
I love your explanation!
Thanks you I needed this ✨💫⭐️🌟❤🎉
thank you so much..had such a difficult time with this earlier
Well, interesting but it seems that at the end of the action potential the axon is full of Na+. It has to flow out maybe by the Na+/K+ pump not mentioned here?
Actually, the number of Na+ ions that have to cross the membrane to depolarize it is relatively small - so small that the concentration of ions hardly changes in larger neurons. That means the number of ions that exit for repolarization is also small. You may hear people say "sodium floods in" during an action potential, but that is a bit misleading because it implies large changes in ion concentrations, and that all that "flood" has to be pumped out again, which isn't the case.
A good analogy would be to say a neuron is like a rechargeable battery. You can get a flashlight to come on many times on one battery charge. Likewise a neuron can support many action potentials firing before ion concentration gradients run down. The larger the neuron, the more APs can fire. The Na+/K+ pump is like a trickle-charger that keeps the neuron's "battery" topped up. It isn't needed for AP firing in the short term, but is useful to maintain normal function over time.
Hope this clarifies things for you!
thanks! very kind of you
thank you so much ive been confused about this for so long now god bless!
Are sodium channels ligand-gated or voltage-gated or both? I think initial action potential is triggered by influx of sodium ions through ligand-gated channels activated by binding of acetylcholine. Thereafter, the action potential is propagated through the entire length of the axon by influx of more sodium through voltage-gated channels.
Thank you for sharring this for us.
Thanks for this helpful video :)
Its very unclear where the absolute refractory period is at. Isn’t at the part of the wave that starts going way positive?
just what i needed
Quite good, quite good indeed.
GREAT VIDEO
Subtitle error in 0:02 in Portuguese (Brazil). It says "ações potenciais" instead of "potenciais de ação".
Can you make a video about Kv channels and backpropogating action potentials?
I need the name of the app that you work on !! And thank you for the explanation 💚💚
Sorry, there are more subtitle errors that I took the liberty of listing:
3:55, 4:24, 4:28, 4:42, 5:06, 5:11, 5:43, 5:54, 5:56, 7:01, 7:33, 7:36, 7:41, 7:48, 8:09, 8:36, 8:59 and 9:16, "ação potencial" instead of "potencial de ação".
9:06 "ações potenciais" instead of "potencias de ação".
1:03, 1:15, 3:08, 4:21, 4:26, 5:08, 5:30, 6:55, 8:28 and 8:48 "membrana potencial" instead of "potencial de membrana".
Seems like every use of those terms is wrong, should be pretty easy to fix.
wow i am shook
Can voltage-gated sodium channels open before hitting the threshold value?
what is the range of absolute refractory period? does it extend til the lowest point of hyperpolarisation or it stops at the point AP has fallen til the resting potential?
is the trigger zone of the axon you're talking about at 1:40 the axon hillock? or is the axon hillock just for summation of input and then this process you talk about happens after the axon hillock? thanks, great video :)
The "trigger zone" is wherever in the axon hillock the AP is started. It's not an actual anatomical structure, but it is usually in the axon hillock so it's pretty much interchangeable
I thought neurons hyperpolarize to a -90mV at the end of the repolarizing phase? You didn't mention anything about that...
Wait, but i thought the absolute refractory period starts from depolarization to repolarization before it hyperpolarizes and repolarizes again?
I think you are right, they expressed it wrong
Hi, i have a question... i though the absolut period happen since the excitatory stimulus cross the treshold until the end of the repolaritation state, but according to the video all the periods occurs during the hiperpolaritation state, then i got confused about it.. can someone take this over ? i will be waiting the answer!
It depends on the source, different books have different definitions
Thanks squidward
Would it be possible to permanently (through damage perhaps) hyperpolarise a neuron?