YTread Logo
YTread Logo

Are Neurons Just Electric Circuits?

Jun 04, 2021
thanks to blindist for helping support this episode you should animate more clones wait this will even work this episode was made possible by the generous supporters on patreon hey guys let's have fun and apply what we know about electrodynamics to the brain of the nervous system it's a field of study called electrophysiology which mainly covers the nerves but also deals with things like the muscles in the heart because you know the nervous system is everywhere. Electrophysiology shares an important history with electromagnetism and physics in the timeline before the late 18th century models. The mechanisms underlying the brain and movement involve various types of fluids and spirits in ancient Greece.
are neurons just electric circuits
Fluid, spirituous things were known as pneuma, but that word has since become a prefix for other words like pneumatic and pneumonia, which are related to gases and pressure in 1646 René Descartes. argued that the neuromuscular system was essentially a hydraulic system where animal spirits flowed from parts of the brain to the muscles, but in the 1790s we began to discover what was really going on in 1786 Luigi Galvani entered the field of physiology is a me luigi no It's not that Luigi, incredible, in 1786 Galvani did some experiments with lightning rods and frog legs, they were dead frog legs, there was no cruelty to animals here, okay, anyway, he attached a lightning rod to some legs of dead frog and moved in response to the

electric

ity. shocks Galvani called this behavior animal

electric

ity when he finally published it in 1791 in an essay called Commentary on the Effect of Electricity on Muscle Movement, you know, a typical boring but descriptive scientific title, eventually Galvani discovered that the lightning rod actually It was not necessary and could be manufactured.
are neurons just electric circuits

More Interesting Facts About,

are neurons just electric circuits...

Dead frog legs are contracted simply by touching them with a combination of two metals called bimetallic galvani. He used this fact to argue that animal electricity was actually intrinsic to the frog itself and, as we will soon see, he was not entirely wrong, but a rival of Galvanize named Alessandro Volta argued that Volta the Volta the Volta we named Volt, yes, that's the one volta suggested that the animal electricity was not intrinsic to the frog but somehow came from the bimetal and it turns out that volta was true, the bimetal is capable of producing its own electricity, the two metals reacted with the electrochemical fluids in the dead frog's leg forming a primitive voltaic cell, erm, a battery, the bimetal turned the frog's legs into a battery, really yes, really volta literally discovered. electrochemistry and invented the precursor to the battery

just

to prove Galvani wrong is crazy, where an argument will get you to the timeline anyway.
are neurons just electric circuits
Voltaic cells set the stage for experimental physicists like Orsted Ampere and Faraday to develop electromagnetism in the 19th century, so next time. Charge your phone, don't forget the frog. Galvani stopped research on it after Napoleon invaded Italy in 1796, but the idea of ​​reviving life with electricity captivated early 19th-century society. It was the inspiration for Mary Shelley's Frankenstein in 1818, so this is going to work, no. definitely not frankenstein it's

just

a story that's not how clones are made okay so luigi galvani was probably stimulating the frog's sciatic nerve a nerve is a biological cable that consists of a bundle of fibers called axons um what is an axon? the part of a typical neuron that carries electrical impulses when it comes to the brain the neuron is usually the star of the show your brain contains about a hundred billion of them isn't that also the number of stars in the Milky Way?
are neurons just electric circuits
Yes, it is the correct order of magnitude, but why? Are you asking? Didn't you say he was the star of the show? Yes, as a metaphor, this video is about brain stuff. So what is a neuron? A simple model of a neuron has three parts, the main cell body, the dendrites that receive signals, and the axons that send out. signs and can sometimes encompass an entire limb. One of the things that makes

neurons

special is their ability to generate and transmit electrical pulses over relatively long distances and do so reliably and quickly enough to respond to the environment, so Galvani was on the right track.
But we have come a long way in our understanding of electrodynamics since then, going back to the timeline, we would have to wait until the 20th century before scientists really pinned down the biophysics of this electrical axon. In 1906, Ramon Ika Hall received the Nobel Prize. award for his pioneering work on the general structure and function of the neuron, but it was not until 1952 that Alan Hodgkin and Andrew Huxley teamed up to discover the biophysical mechanism of electrical pulses and

neurons

. Hodgkin and Huxley were both biophysicists, so they decided to tackle the problem and did their experiments with the giant squid axon a giant squid axon about 20,000 leagues under the sea a species of giant squid no no no no a giant squid axon squid a giant squid axon the axon was giant not the squid that made it more accessible and easier to work with, I mean who wants to work with a small human neuron?
Am I right anyway? If you look up the Hodgkin-Huxley model you'll probably see differential equations that look like this, of course the equations don't exude intuition, so instead let's try to make a visual image, think of a neuron as a bag of charged liquid with leaks. It is mostly water, but has ions like potassium, sodium, and chlorine dissolved in it. A neuron, like all cells, has a two-layer cell membrane when it is not doing anything. The neuron maintains a potential difference, a voltage across the membrane. How does it do that? ion pumps ion pumps work with chemical energy known in the bioworld as ATP this is one of the main reasons why our brains consume 20 of the energy we eat outside the cell there is a higher concentration of positive ions such as Sodium inside the cell there is a higher concentration of positive ions such as potassium.
Negative ions like chlorine are scattered everywhere. Ion pumps are specialized protein structures embedded in the cell membrane that pump specific ions against the concentration gradient and against the electrical potential, if necessary, find the gradient. I know this all sounds very biological, but it's just electrodynamics, it's just circuitry stuff. Ion pumps use energy to move electrical charges, that's what batteries and other voltage sources do in the Hodgkin-Huxley model. like batteries, remember the cell membrane has two layers, well that's just a capacitor, the ion pumps build up electrical charge on each side creating a voltage in the Hodgkin-Huxley model, the cell membrane is a capacitor, the Ion pumps are not the only devices that span the cell membrane, although there are also ion channels; when these channels are open, ions can and will try to balance their concentration.
Ions are just electric charges and when charges flow we call it electric current, it is also positive charge so the conventional idea of ​​current is not. It's even a lie this time, but what really matters here is what the ion channels represent in the circuit. Ions do not flow through the channels all the time and flow at different rates at different times. It is very similar to a variable resistor controlled by some type of timer in the Hodgkin-Huxley model. Ion channels are variable resistors that control electrical current using Ohm's law like any other resistor. Each ion channel is selective, although it will only allow a specific type of ion to pass through the sodium channels alone. let through sodium ions potassium channels only let potassium ions through so how are they variable because they are voltage gated?
There are actually several different ways that an ion channel can be activated chemically activated channels in cells that neurons communicate with mechanically activated channels that are sensitive Press or stretch and even illuminate channels in the eye, but those in the axon They are voltage regulated. Its opening depends on the voltage across the cell membrane and that voltage can change over time, in fact it will change over time. As that neuron tries to communicate with other cells, these voltage-gated ion channels are vital in carrying a signal to the end of the axon, the signal moving up the chain.
Hodgkin and Huxley modeled this process as a simple electrical circuit. The cell membrane is a capacitor, the ion pumps are rechargeable batteries, and the ion channels are variable resistors. Let's take a look at the voltage across the cell membrane, also known as the capacitor. While the nerve is trying to send a signal, there are four stages at rest: depolarization, repolarization, and hyperpolarization. Jargon alert, alert, I've been driving for prizes this whole video, now it's time for you to take care of my case, okay, okay, I guess technically the membrane is polarized as long as there is a voltage across it , which, as you can see, is true almost all the time. goes from zero twice, but we have to differentiate these stages, so it helps to think of polarization as just the resting state the membrane is stable depolarization is when the voltage increases toward zero but is exceeded repolarization is when the voltage rebounds and falls towards the Hyperpolarization in a resting state is when the excesses do not become too obsessed with names.
Wasn't this supposed to be about

circuits

? Oh yeah, yeah, sure, we were talking about the Hodgkin-Huxley model, but I think this will make more sense if you look at it all together, let's sync the three images first, the voltage-gated sodium channels are activated to open, allowing a rapid flow of sodium ions into the cell, the voltage across the membrane goes from negative 70 millivolts to about positive 30 millivolts, but remember that we are on a stopwatch, so after the initial spike, the sodium channels close, when they close, the potassium channels open rapidly, sending potassium ions out of the cell, the voltage across the membrane falls back towards the resting state, finally, after an excess, the potassium channels potassium are closed and the membrane returns to the resting state, it does so by filtering a little and, if necessary, turning on the ion pumps, in short, the channels balance the concentration of ions and the pumps unbalance them again.
The Hodgkin-Huxley circuit successfully models this entire mechanism, but only for a small patch of the cell membrane, this patch only has a few things: a sodium-potassium pump, a potassium channel, a sodium channel, and any other Whatever device is around, the signal process begins locally, usually around the location of the cell body and axon, and then spreads as a chain reaction from one patch of membrane to subsequent local regions, depolarizing its neighbors sending a pulse down the axon and this happens fast, fast, the entire activation process begins and ends in approximately one thousandth of a second, but at what speed does the signal arrive? it takes to go down the axon good question, it actually depends, it varies a lot depending on the type of neuron and the animal species, but at maximum speed we are looking at approximately 224 miles per hour or one hundred meters per second, which is the length of a field football, including end zones, in a single second compared to how fast signals travel over wires, although this is actually quite slow, oh no, that gives the robots the advantage anyway, so it took us a while to discover neurons.
The real work began with luigi galvani. and dead frog legs, but they culminated in Alan Hodgkin and Andrew Huxley in their circuit model. A neuron is like a simple electrical circuit or at least a chain of simple

circuits

. It is made of capacitors, batteries and resistors, which obey Ohm's law. they create a pulsating voltage all just to tell other cells what to do, let's stay here for a while and take it all in, so if you have any questions about this analogy, please ask in the comments, thanks for liking and sharing this video, no forget to subscribe if you want. to stay up to date with us and until next time remember that it's okay to be a little crazy.
I'd like to thank this video sponsor, Blinkist, have you ever been in one of those social situations where everyone is talking about some popular nonfiction book, but you haven't? Read it, I mean, who has time to read a book in this fast-paced world we live in? I have more important things to do. Blinkist can solve your problem. It is an application that you can download on your phone or tablet. I don't even have a SIM card, okay, I use an old phone for podcasts and stuff, okay, anyway, BlinkistIt takes the best ideas from more than 3,000 nonfiction books and condenses them into about 15 minutes.
You can read the summaries yourself or even listen to them. Someone else reads them to you. They have books from across the spectrum, like Born a Crime by Trevor Noah or A Brief History of Time by Stephen Hawking, all condensed into about 15 minutes. They've even started offering member discounts on full audio. books, if you like that sort of thing, the first 100 people to visit the flickist.com science asylum can get unlimited access for a whole week to try it for free, if you don't like it, you can cancel at any time during that week. but if you decide to keep it, you'll also get 25 off the full membership price at the end of the one-week trial.
Visit the flickist.com science haven or click the link in the description below to get started. Featured comment comes from Derek. Cochran, who said that relativity is definitely not easy to understand. I see what you did there. Cinch as in hyperbolic sign, well anyway, thanks for watching.

If you have any copyright issue, please Contact