 Good evening. I'm going to talk to you about ion channels. So that means we're going to answer this question. What are ion channels? Okay, I'll forgive you if you haven't asked the question before yourselves But ion channels are actually a lot closer to all of our lives than many of us realize and there wouldn't be much life without them So let's dive right in So it sounds a little bit esoteric or technical maybe so let's try and break apart the question for a start What are ions? So here are some ions that you're probably familiar with already, right? This is ordinary table salt it's made up of ions of sodium and chloride I'm sure you've heard that name before so ions are just atoms that have an electric charge So these guys are positively charged and the chloride ions are negatively charged Stack enough of them together you end up with a crystal of salt Now we know what happens if you drop some salt into water it will dissolve, right? This just means that the water molecules get in between the the ions Then breaks them apart and now you have your sodium and chloride ions floating about in solution and this is a Common situation actually so you often find ions floating about in water for example in the ocean We know that salty water. There's heaps of ions floating about there In your food as well think about soup for example, that's got a lot of salt in it that's ions floating about and Also in our bodies our blood and other body fluids also contain a lot of ions This is what's going to be important for us right now So that's ions Sort of channels You probably already have an idea about this one. So I'll just show you a picture of a channel that I like This is a canal in Venice So what is it it's essentially just a pathway that a boat can move through because it can't move through the buildings I hope you know this already so What ion channels ion channels are just pathways for ions to move down, right? So obviously these are not ions. These are not ion channels. These are ions, but this is not an ion channel. So Where are all the ion channels? Well, it's true to say they are actually in Venice You do find them there and you find ion channels in Munich as well and right now in this room There are trillions of ion channels So if you want to find out what they are you just have to look around at your neighbors because ion channels are in all of us Or more specifically they're in the cells that make up our bodies now It's not just us of course all living things are made up of cells and all of those cells contain ion channels So all of these guys plus more whatever you can think of that's alive. So that includes birds and bats all kinds of plants And even down to single celled organisms like this amoeba here or even bacteria They're all alive. They all have ion channels so let's have a closer look at cells and see where And see where the ion channels are and what they're doing so we'll take ourselves as an example because we're all narcissists I assume and So we see here a diagram of Human where you can see some organs. So there's a brain up there and There's a heart and you can see so kill a Tory system some arteries and veins all of our organs are made up of cells We just have a look at one of them. We would see that a Cell is basically just a bag of salty water with a few other things inside that I won't go into and What keeps all that salty water and other stuff contained is the cell membrane or on the outside The main job of the cell membrane is to stop things from getting out and to stop other things from getting in It keeps the inside separate from the outside But sometimes the cell does want to move things across the membrane. He wants to move stuff in or out Some of those things are ions The problem for the cell ions can't get through the cell membrane. They'll bounce right off So to solve the problem The cell manufactures small tubes made out of protein and inserts them across the membrane So now it will have so the tube traverses the membrane and now that there's a hole and this is our ion channel So now the now the membrane the cell membrane has all these little these little pores or holes in them and now In it and now ions can pass through The other issue for the cell is that it wants to control wasn't to keep wants to keep control So wants to control when ions move in and out and so this means that ion channels are in general closed And they'll only open under specific circumstances when the cell wants them to so To have a look at a closer look at how this process works We'll have a look at one of our basic physiological functions that we're all familiar with which is movement That is moving our muscles this is just a Diagram of some of the muscles around the shoulder and arm and Like all our organs muscles are made up of cells the muscle cells they tend to be long and thin you might guess that they have a membrane and There are some ion channels in that membrane very important for for muscles is Are these protein filaments that are capable of grabbing on to each other and pulling each other together and And this pulls the ends of the muscle cell together So the muscle cell contracts and so when enough of your cells contract together your muscle contracts and you can move And the central part of this process is that calcium is bound to these protein filaments specifically calcium in the form of ions So if you wonder how the ion can get inside the inside the cell now we know right they can get in through ion channels so let's have So let's say exactly how this process works So say you want to move for some reason you have an itchy nose you want to scratch your nose so you have the thought I'm going to scratch my nose you send the thought down your the signal down your neurons and One of your neurons will project a process all the way to the muscle that you want to move and it will terminate We'll end very close to the mark to do the muscle cell When the signal that you want to send gets down to to to scratch your nose gets down to the end of the of the The neuron it releases a message a messenger a chemical messenger called a neurotransmitter This is the signal for the muscle cell to contract So there's no point sending a signal if that signal can't be received And so for the muscle cell the way to receive the signal is through ion channels. So these green ion channels here Have a special Spot on them that neurotransmitters can bind to and it's kind of like a key in a keyhole So these neurotransmitters transmit transmitters attached to the ion channel Unlocks the ion channel it opens and now ions can move through So you see speak and see probably that this is not our calcium ion That's the one we want to get inside That's because these ion channels are just the the guys that receive the signal and tell the muscle to activate What they do is they initiate an electrical signal that is passed to the These other ion channels the calcium channels which allow the calcium ions to get inside The calcium ions can bind to the protein filaments the muscle contracts. You can scratch your nose So that's how ions ion channels of different types being opened at specific times Allow us to do simple things like scratching our nose And we know that as long as we don't do anything too ambitious this process Usually works out pretty well most of the time But there are substances out there that can interfere with the function of our ion channels And disrupt our physiological processes like moving our muscles So these substances tend to be things that we call drugs or toxins so Toxins for example are just are just natural poisons some things that you find in nature that disrupt your physiology in some way usually harming you and so some toxins work by Binding to your ion channels and interfering with and interfering with how they work Some for example can stick to the same spot on the ion channel as the neurotransmitter usually sticks The problem for for you is that and for your ion channels is that the toxin doesn't work so much like a key as like sticking some chewing gum into a lock so It doesn't open the ion channel But now neither can the neurotransmitter you can't get the key into the lock. That's full of chewing gum So this means that no matter how much of a signal is being sent by the neuron to the muscle it will The muscle will never really receive the signal. I won't realize that it's being told to contract The toxins can work in different ways as well. So now yeah, so now this is this site is blocked Another way that toxins can work is simply by plugging the pore through which ions can move So even if the channel is open see we've got a neurotransmitter attached the channels open But there's no way for the ions to to move through so again even though The signal is being sent and in this case the channel is open the muscle never realizes that it's getting a signal because of this toxin so Now let's have a look at a real-life example of one of these one of these toxins and And how it works So this is a plant that you find you can find in rainforest in South America and it contains a toxin that Specifically affects these ion channels that I've talked about already which receive a signal from your neurons and they work like these Chewing gum in the lock type toxins and it blocks the site Where a neurotransmitter usually binds and so your muscle can't contract This toxin has been used traditionally by by native people in South America when they were hunting So they use this so it's common to use this kind of a weapon So it's a blowgun and so it involves putting a dart inside the tube and then blowing that dart towards prey animal that the hunter wants to eat and they To ensure success it was typical to dip the tip of the of the dart in the poison that's extracted from these from this plant and So then when the dart hits the animal the toxin goes into its blood and into its muscle it blocks up these ion channels and now Even though the muscle is trying to even though that the animal is trying to tell its muscles to move it doesn't work It's paralyzed it will fall to the ground and the hunter can go and collect it so when Europeans came to South America they of course they eventually learned about this these sorts of toxins from the native people and Eventually some of it made its way back to Europe in there and also in the US Doctors sort of began to think that maybe this could be useful in medicine Because maybe if you didn't give enough to actually kill a person you could just give enough to relax the muscles And there are some situations in medicine where it's really useful to To have this kind of substance to relax the muscles of a patient for example in surgery so It's It's a lot easier to put to perform a surgery if the patient's muscles are completely relaxed and so doctors tried to apply this this particular toxin in conjunction with anesthetics and And it does work But it turned out it was a bit too unpredictable to use Routinely and so after some time although it was the basis for the development of synthetic drugs that work with Exactly the same principle or similar principles to the toxin but are more more easily controlled So these are just two examples of situations where ion channels can be interfered with to To to affect our physiology But there are thousands of other substances out there toxins and drugs that can interfere with our ion channels and These substances are so effective at interfering with our physiology because our ion channels are so important for so many of our functions So I've talked about muscle tonight And how important ion channels are there, but all of our bodily organs are made up of cells and all those cells have ion channels That underlie how they work so including your brain your liver your heart your lungs pretty much all of it and in every case If you didn't have ion channels there that organ is not able to function properly So that is basically how close to your lives ion channels really are and And so yeah, so even though you can get by without thinking about them most of the time it's it's fair enough Now you know at least that even when you're not thinking about them They are they're still working your way in opening and closing just at specific times when your body wants them to To underlie all these essential functions that they keep us alive. Thanks Now we have some time for questions, please Please If I got you right You mentioned that there are Two types it is two types of these ion channels this for sodium at all calcium Yes, so the question is if there is a two types of ion channels or only two types No, there are many types. There are Dozens possibly more than a hundred So it's not over yet Okay Have you finished is a question Let's stick to one I think Let's stick to one is so it's it's over. Yes So that they could you you can by way approach the speaker stuff to the event and talk about So the question is if there are different types of ion channels, how they control what exactly they're passing through For example by their charge, maybe they control it. Yep, sure. So they're different ion channels They let through different types of ions some are very specific For this case for calcium as we saw or for that and yeah, it depends on the the pore size On this yeah, the size of the hole through the through the middle of the channel And other things like the particular amino acids that are inside and how they interact with the ions as they come through So there's different ways there's a couple of different ways, but simple size is one way that Selectivity is controlled So some more questions, please So now that we know that they're like different ion channels I wanted to know if there are differences in ion channels from the human body cells or Probably like let's say bacteria body cells so that you could like develop a drop which is just specifically targeted So the question is are there mechanisms of ion channels different in bacteria and maybe humans for example And if you can specifically target the ions which are in the bacteria. Yep, sure There are yeah, there are big differences between species It's function of ion channels in bacteria is not really clear at this stage But I'll tell you a good example, which is the comparison between a type of ion channel But that's essentially the same but it's diverged through evolution between mammals and birds and And this ion channel is the stuff that detects the capsaicin in Chili's so that's why chilies are hot and The mammalian ion channel is sensitive to this stuff, but the bird version is not So it means that birds can eat chilies fly away and like poop out the seeds somewhere far away But mammals that usually crush up the seeds try and eat it And then and don't they don't eat the chili anymore. So yeah can vary even just between birds and mammals It's very convenient Some other questions What you can do to the what What you can do to keep the channels clean I'm not sure. Okay, so they're really tiny cellular components so Something goes wrong with an ion channel the cell will just take it out and trash it and break it down Into its constituents make a new one and put a new one in So for you that just means Eating your vegetables and being healthy That's there's not really like this there's not an avoiding We're just avoiding drugs and toxins that that are gonna lock up your iron that actually gonna cause trouble for your Channels, but in general you don't need to worry about them getting dirty or wearing out on this sort of thing it's just Just part of yourselves that will be recycled over time. We will come to a topic of public health in the next Next talk, so thank you Alex