This video explains how voltage-gated sodium channels work in neurons, and how they influence the shape of an action potential graph. Animation and voice-over by Laura Slusser.
I can't believe that, 2 years already in medicine and it's the first time i come across with such a complete and comprehensive illustration of those channels. Thank you...and please make more videos. Instantaneous subscription!
i am a med student and this is one of the best videos who explain it very comprehensive and intuative i appreciate it a lot what i would like to see more if its possible like a time line of what exactly happen from the post synaptic cleft to the action potential itself that go through the axon and axon terminal but really thank you so much incredible video!!
Thank you for explaining this concept for my biology course. I am an environmental science student. Sometimes these courses are not fully explained to us because we are not med students. But we do need to understand the content just as well!
I’d like to see more. Love seeing how they worked. Trying to visualise how densely packed they are with each other and if there is differing density’s on the axon, maybe more near the end?
Ah beautiful stuff! You explanation is so vivid, it's amazing. Please upload more videos in the future! I have one question though: How does the inactivation gate work? I mean, how does it know when to close? Is it voltage dependent too? Does it carry some charge as well?
Please please if possible make a video on Class 1 anti arrythmics too. With all the details of how they act on open and close state of sodium channels in myocardium. much needed!!!
I was never sure how to imagine the AP to travel along the axon on a molecular level. Are individual sodium ions simply traveling along the whole length of the axon? This helped me understand that ion channels at every node of Ranvier open and just gradually fill up the axon - very helpful, thanks! ♡
Excellent presentation/visualization of the mechanism responsible for Na channel opening and closing. 👍 Question: What triggers the inactivation gate to close the channel at -30 mV? Is it also positively charged and gets repelled upwards by higher Na concentration inside the neuron therefore blocking the Na channel?🤔
Cartoon animations are extremely helpful, thank you for making it! For Na v-gated channel, could you explain/demonstrate the actions of: Selectivity filter (by which sodium is allowed & passed through & K is rejected), and Fast inactivation (how opening of the pore gate closes the inactivation gate)? (And how these parts derive from the 6 segments of the 4 domains of the channel?) And isn't the actual pore gate at the bottom of the pore (intracellular side), rather than at the top on the extracellular side that you showed?
Yeah that’s absolutely fantastic animation. It is easy to visualise and understand. I have the same comment about the flowing of the Na+ ion. It looks the concentration of the Na+ ion is less outside than inside before opening. Which I think is the opposite and that will make sense as the transport system has to be diffusion ( from an area of high concentration to low concentration. Thank you for all your efforts Xxx
Improvement suggestion to this visualization: - Positively charged pink voltage sensor are insensitive to positive sodium ions concentration outside the neuron but sensitive to sodium ions concentration inside the neuron. If the pink voltage sensor are sensitive to both the outside the neuron and inside the neuron of the sodium concentration, then when the channel is open the sodium ions concentration could not flow against its concentration gradient. If the higher sodium ions concentration inside the neuron opens the channel then the sodium ions could flow out but not in! Solution to this is when pink voltage sensor are sensitive only to sodium concentration inside the neuron and opens the channel when there is a stimuli, allowing higher concentration of sodium ions outside the neuron to flow inside, down its gradient concentration, not against it.
So how does this get affected by pyrethrins? Like why would the channels be kept open? I was reading about shock dope lol I’m just curious as to what is happening in the brain that ordinary flowers can’t derive the same compound from, like how chrysanthemums can make pyrethrum for pesticides after undergoing a process
Why does the number of sodium ions increase within the cell when the neuron is receiving an excitatory signal? Isn’t that a result of the gated channels opening?
At resting potential, there is more sodium ions outside and less inside . And you added ,on arrival of impulse , Na+ ions increase inside. How does it happen ? Or what cause increase in Na+ ions before the actual influx of Na+ from outside ?
The first Na+ ions enter the cell via some kind of stimulation at the synapse. For many neurons, this happens via ligand-gated channels that open in response to neurotransmitters. But you can also have an electrical synapse, where the graded potential arrives through a gap junction. Alternatively, in the hair cells of the ear, there are ion channels that open in response to vibration. In the skin, there are sensory neurons with channels that open in response to pressure or heat. It all depends on the type of neuron.
I always knew there was a gap in my knowledge regarding how the membrane potential is initiated. Textbooks do a bad job explaining that there are actually sensors that can sense changes in membrane potential... Thank you for your complete explanation!
