SciShow Tangents - Nerves

Starting point is 00:00:00 Hello and welcome to SciShow Tangents, the lightly competitive science knowledge showcase. Hank is on spring break, so this week I'm your host. I'm Sari Reilly, and joining me this week, as always, is our resident everyman, Sam Schultz. Hello. And taking my place on the science couch is Tangents editorial assistant and co-host of the podcast Tiny Matters, Deboki Chakravarti. Hello. Did you think of a question for us, Sari?

Starting point is 00:00:42 I did think of a question for you. I thought of it really with Deboki in mind because I've been wanting to ask her this question just as part of our friendship. So you can also answer it though. I'm excited. Nobody ever asks me any questions. That's fine. No, it's for both of you. So if a casting director came up to you and was like, we would like you on our reality

Starting point is 00:01:02 TV show, what show would it have to be for you to say yes immediately? I think it would be tough. I do think it would have to be Amazing Race. I think Amazing Race is like the right combination of super fun, challenging, and like not geared towards embarrassing yourself. I mean, I've watched people embarrass themselves on the show, but it's not like, like I would love the idea of being on a Real Housewives show, but only if no one ever sees it. But Amazing Race, I think like, you know, the goal is not for me to be the subject of humiliation necessarily. If I if I am, it is purely through my own doing. So I think I'd have to go with Amazing Race.

Starting point is 00:01:41 Would you do it with your husband? Would you be a race partner? Yeah. So I think I'd have to go with Amazing Race. Would you do it with your husband? Would you be a race partner? Yeah, when we watch, we definitely do the like, okay, you're in charge of this task and I'm in charge of that task. That's an important part of being on the Amazing Race is knowing who you'd be partnered with. I guess there was one season

Starting point is 00:01:56 where they were paired up with strangers, but still, you gotta know. Yeah, I could not do it with a stranger. I could not just be like, yeah, I'm gonna trust this whole thing with a stranger it would be bad i don't really watch reality shows so i'm gonna be a little useless so i was gonna say amazing race too because i think i like i could do puzzles i think and rachel could tell me where we're supposed to go i don't actually know what they do on amazing race i assume there's someone with a map and someone

Starting point is 00:02:23 solving puzzles is that close that is a lot of it yeah no that Race. I assume there's someone with a map and someone solving puzzles. Is that close? That is a lot of it. Yeah. No, that's pretty good. There's some physical challenges. Sometimes you have to climb a rock wall or random things like that. Oh, okay. And sometimes you have to learn a dance, too. There's a lot. Sari, what would you do?

Starting point is 00:02:40 That's also my answer. This has become the Amazing Race fancast. Wouldn't this be a good season? Okay, listen to it. What channel does this come on? CBS. CBS. Listen to us. Deboki and her husband,

Starting point is 00:02:52 Sari, and I assume Sylvia. I don't know actually who you'd pick. Absolutely. Sam and Rachel, Hank and his wife, Hank and John, all of us, different teams on one season of The Amazing Race. Podcaster season.

Starting point is 00:03:04 It would be incredible. They call it the even more amazing race. So every week here on Tangents, we get together and talk about The Amazing Race. But actually, we try to one up, amaze and delight each other with science facts while also trying to stay on topic, which happens sometimes, but sometimes we devolve into friendship conversations. Today and every day, our panelists are playing for glory and Sari bucks. I got the currency now, which I'll be awarding as we play. And at the end of the episode, either Deboki or Sam will be crowned the winner. And now, as always, we introduce this week's topic with a traditional science poem. This week, from me, I'm not stopping talking for a while.

Starting point is 00:03:54 A gentle breeze, a grazing touch, a warm cat you love so much. Sensing friction, cold or hot, these nerves you've got sure do a lot. Inputs of light or hums or sweet, they're in your nose and in your feet, stretching far from spine to skin, fibers small and strong and thin. Back and forth they do relay what your surroundings have to say, sensing joy and sensing stress, a guess for your brain to process. Without them all, I guess I fear we'd all just be some goo. No thinking and no feeling and no knowing when to poo. So even with the pain of grief or when you skin your knee, I'm real glad to have these neurons interwoven into me. Wow. You're smart and creative. So the topic this week is nerves. just just to give my vocal cords a break for a second

Starting point is 00:04:50 sam what are nerves oh fuck i should know what they are because i hypothetically researched a bunch of stuff about nerves yeah uh okay so there's something called neurons. They're the cells that make up the nervous system running all through your body. And there's little there's little guys that poke out and they're like, what's going on? Sometimes a hot thing touches them and they go, hey, brain, there's a hot thing down here. Sometimes a soft thing touches them. They go, hey, brain, there's something. Sometimes it's on your tongue and it's like, ooh, yummy or ooh, nasty. But there's a little guy with a little wire

Starting point is 00:05:28 that goes to your brain. And that's what a nerve is. I think you guys should do this every week. In place of giving the definition, this was captivating, especially the performance art. I mean, unfortunately people can't see the hand motions that accompanied your definition. Like, yeah, there were pokey fingers coming out of the forehead. It was incredible.

Starting point is 00:05:52 It was your interpretive dance of I'm a neuron. Yeah. Is that correct? You know, you're not that far off. So neurons, like you said, are considered nerve cells and like the building blocks of the nervous system. From what I can find, a nerve, like when we say like a nerve gets activated or a nerve transmits chemical or electrical signals, it seems like we're mostly referring to like the peripheral nervous system. So like your central nervous system is your brain and your spine and your peripheral nervous system is the stuff that extends out to like your brain and your spine. And your peripheral nervous system is the stuff that extends out to like your legs and your fingers and your toes. So the really long nerves that start like the cell bodies. So in your interpretive dance, your head is by the spine, but then

Starting point is 00:06:40 all the little feelers stick out and go down your limbs and are like long winding filaments and fibers that stretch out to relay information back to your central nervous system. Is that part of your brain? It's part. They're not like brain cells, but they talk to your brain. They like communicate information to your brain. Okay. to your brain. They like communicate information to your brain. So yes, in that the information gets relayed to your brain, but no, as in your brain is not a big web, like a jellyfish. Your brain is pretty centralized and people say like your brain is whatever is in your skull,

Starting point is 00:07:19 that goo. People are always saying that. People are always saying that. Yeah saying yeah and i guess there are different kinds of nerves this is where it gets like a little wishy-washy and the way that we don't like our brain is us thinking about ourselves our nerves there are millions of them across our bodies there are a lot of like small bundles of fibers and they sense so many different things so like you said they can sense hot and cold. They can sense different pressures, like a soft touch versus like a hard touch or a punch. You know, the hard touches. But they can also sense like electricity conductivity.

Starting point is 00:07:57 So like how sweaty you are can change how your nervous system interacts with the outside world. Or like you have your optic nerve which helps with light like you have special nerves within different facial features that do particular senses so to my knowledge or to my understanding and trying to like research the definition of nerves we haven't nailed down all the different categories of nerves and we have sort of like buckets of them of like these ones help with senses and these ones help with controlling blood pressure and digestion and these ones help with muscles. So like if you think they help move your finger muscles or whatever, but we don't necessarily

Starting point is 00:08:37 know all the different types within that. Well, where does this word nerves come from? So it comes from Latin nervus, N-E-R-V-U-S, not O-U-S, which means sinew or tendon or cord or like a string. So it's more about the shape of the thing. So they probably dissected animals and or humans and were like, man, there are strings in here. Let's call them nerves. Okay. You say call them nerves. Okay. If you say so, Plato. And it seems like because we had such a rudimentary understanding, like we're just digging through these flesh sacks

Starting point is 00:09:15 and trying to figure out what was going on, they used nerve to describe both a nerve, like a neuron, like we would describe in the modern sense, or like a cluster of neurons, as well as to mean a tendon. But those are like also sinewy and like stretchy and stringy. There was like confusion between nerves and tendons. And then eventually, I think we decided to differentiate somehow. I don't know how tendon got its word, but nerve one, for some reason, it was like, it's the stringiest thing. So you got to be called nerve. What's weird is that I

Starting point is 00:09:51 can't really pin down where the adjective nervous came from, like meaning scared or anxious, because in the 1600s, nervous and nerve actually meant like the brave sense of it. Like that guy's got some nerve. It meant like strength or vigor or force because nerves were these things that were holding your body together and like giving you the bad sense of like being like cheeky or also being like anxious or hysterical came from the late 1800s. So it's more recent than that. First, like the discovery of nerves sounds like just so like you're like, yeah, you're going through the flesh sack and you're like,

Starting point is 00:10:44 oh, look at these strings. But you're also talking about like how we haven't discovered all the nerves yet and I I mean I feel like that's like one of the things that's so weird about the human body because there's just like so many things inside of it and so like you somehow it feels like there should be a finite number of strings which means we should have found them all but I guess not like that's not how it works and they're so small that it's like I don't know yeah get much smaller than this yeah I don't know how to like magnify these or understand what they do and then we spend all this time in school trying to learn like oh well how do we develop tests around bathing these tissues in other molecules to guess at what they do because we

Starting point is 00:11:23 can't really see. Yeah. But we can like kind of guess. Hey, I just don't worry about it and I'm doing all right. Yeah. So all that chatter about nerves, we like kind of know what they are, but kind of don't. And that's going to be the theme of this episode because it's the theme of tangents, which means it's time to just move on anyway to the quiz portion of the show. This week, because nerves are related to human brains, which we barely understand, and electricity, which some people understand, but I am unfortunately not one of them, I figured it'd be good to stick with the basics and do an old-fashioned truth or fail.

Starting point is 00:11:59 So I will present you with three science-y sounding statements about nerves, but two of them are nerve-wracking garbage lies, and one of them is a true fact. And you will have to use your brains or gut feelings or whatever to decide which one is real. Number one is pain is a complicated sensation because it has to do with nerves carrying signals to your brain, which then interprets those signals as ouch, like we were talking about. So easing pain, especially in diseases like arthritis that can have a combination of inflamed tissues and nerve damage that cause more stabbing kinds of pain, can be tricky. In ancient Greece, though, they treated arthritic pain by putting electric rays, like the big flat fish, on the achy area until the low to medium level voltage turned it numb.

Starting point is 00:12:45 When their nerves regained feeling and function again, they would be hopefully cured or at least feeling a little better. Number two is back in the 1700s when scientists were a little more like mad scientists and learning about electricity, they needed to find ways to test whether there was actually an electrical current around. And what better way to do that than using animal nerves? An early device was called the mouse galvanoscope, which was basically a severed mouse tail with the nerve endings exposed that twitched when it was connected to something actively electrical with voltage. It was a really sensitive, quick and easy measurement device, though kind of gross.

Starting point is 00:13:23 And number three is, also in the fast and loose days of the 1800s, when scientists were touting the benefits of using electricity on biological things without a lot of concern for safety, the most talked about example is electroconvulsive therapy or other voltages applied to brains. But some people were experimenting with other kinds of nerve endings, specifically the facial nerves associated with taste. While electric current, like licking a battery, can produce a metallic or sour taste, some people were experimenting with zapping tongues in different locations to produce other flavors, like sweet or salty. But the nerve damage that resulted from this novelty meant that these experiments died out before they could become a widespread fad. So the three facts are, one, ancient Greeks use electric rays to soothe arthritic pain. Two, scientists in the 1700s used mouse tails as galvanoscopes to check for

Starting point is 00:14:16 electricity. Or three, people in the 1800s tried to induce flavors on the tongue with electricity. I just don't think if you take an electric ray out of the water, I feel like they don't work anymore. I don't know if that's true or not, but I think they need to be surrounded by the water to really make you hurt or to really be able to feel it at all. That's my theory. I don't know enough about how I would try to use electric rays to soothe arthritic pain,

Starting point is 00:14:43 but I think you might be right. Maybe. Trust me. I've been doing this a long time. Now, the second one, that sounds reasonable to me. There's mouse tails all over the place. Wait, so, okay. So I don't understand.

Starting point is 00:14:56 They're checking for electricity. Like, what does that mean? Like, they're looking, they're hunting it down. Like, they're trying to find the electricity that is invisible to them so they're not waving around the mouse tails just being like is there electricity over here yeah they were a little bit more methodical than that it was more like if they were making a battery or making a circuit or something like instead of like you know those potato batteries or those lemon batteries you put a light bulb in to see

Starting point is 00:15:25 if it's completing the circuit and if there's electricity instead of that they would put a mouse tail and be like it's wiggling so there's electricity here whatever i'm building is working or i can there's something measurable going on here i just feel like a mouse tail is already so wiggly like because like i get a because, like, I get a frog leg. Like, you could use a frog leg and it would be, like, you know, it would be twitchy. That feels like a good confirmation. I'm not sure I feel like a mouse tail would be, like, a good enough. Gosh, well, so, okay, maybe she just subbed out mouse tail for frog leg.

Starting point is 00:16:00 Yeah. Kind of against the spirit of the game. We'll see if that's if that's the case though just swapping one word come on and the last one just seems like i just feel like if this worked we would still be doing it if we if we could induce flavors on the tongue with electricity i don't think nerve damage would be stopping anybody i actually think there is there is like a thing that has been invented that you can lick and it makes different flavors. It's just like a reusable lollipop is what they like. You can't get one, I don't think.

Starting point is 00:16:28 But I think this is something that's been made. So Sari confirmed full of shit on that one. But we've just called her out on every single one. Presumably one of them. I think number two is the real one. You're just a naysayer on that one. That's true. I'm a naysayer on every one.

Starting point is 00:16:43 number two is the real one okay i'm gonna go with just a naysayer on that one that's true i'm a naysayer on everyone um but that's because i feel like the secret game within this game is always sari and i trying to see who can get who to overthink the most um absolutely and this is just one of the few times where we get to do it like she gets to do it to my face i'm gonna go i'm gonna go with the third one i am gonna go with the flavors one just because i like it i like the idea of it you You're out of your mind. I might be, but I'm not overthinking it. I am just going with I like this. I like the idea of it.

Starting point is 00:17:11 And you're both wrong. So number three, the one that Deboki chose, I kind of made it. I also like I made it up and then I Googled it to be like, is there anything like this? I found something from 2014 that was some sort of design challenge across universities for the Stanford Center on Longevity, which was an odd from the national university of singapore called taste plus which like electrically stimulated taste buds to just enhance taste as far as i could tell but that that's like the only thing i could find and they didn't follow up on that research at all and all i could find with like taste buds or taste related nerves and flavor was like licking batteries because that's the question everyone asks like what is the battery i'm looking taste weird

Starting point is 00:18:11 so i also thought it would sounded cool which is why i made it up number two it was a frog leg devoki sussed it out uh very good wait Wait, so the galvanoscope is a real thing, but it's just with the frog legs? Yeah, it was with a frog leg and trying to identify sources of electricity that were strong enough to make it twitch. And it was specifically because of the sciatic nerve. So you've got this nerve that goes from your lower region of your spine down your leg and it's a pretty major conduit of information across your body like if you've heard of sciatica that's like a condition like nerve damage to the sciatic nerve and can like cause pain and whatnot and so it was like particularly easy to rip a leg off a frog and then like peel back the skin a little bit and

Starting point is 00:19:06 then have that nerve just sticking out whereas like a mouse tail there are nerves in it but there isn't like a major nerve running down it so you really it's too floppy on that lie yeah too floppy but yeah number one is surprisingly the true one. There's a whole paper on it, how Greek old dudes were just like, we got to eliminate pain. How are we going to do that? Using the torpedo fish, aka the electric ray. And I couldn't tell if they like took it out of water or just like kept it in like a pool of water, but they would put it under people's feet or under people's hand or over people's arms and then wait till they got numb and just like hoped that they would cure pain because they kind of didn't understand electricity, but kind of knew that it's like something was going on with it and like knew there was some sort of like energy current going on and so they used it to try and cure arthritic pain to try and cure headaches to try and cure like gout or random

Starting point is 00:20:12 things they were just like oh you're suffering slap an electric fish on it and then maybe it'll cure you and like your nervous system ailments well that was a was delightfully devious. Yeah. I'm so glad. I, yeah, I always feel like when I get got, Deboki's chuckling, like in the distance listening. So I do feel like I got got on a technicality. I mean, you had the floppiness was just such a glaring issue. I don't see an issue with the floppiness. You're really hung up on the floppiness, but I think it would be fine. I think you stick it on, the mouse tail goes, doink. It goes unfloppy. Then you know.

Starting point is 00:20:50 I see. That's very cartoon logic. Mouse tail is floppy. Circuit is sloppy. Mouse tail is straight. Circuit is great. That's good, yeah? Yeah.

Starting point is 00:20:59 Yeah. And with that, we're going to take a short break. And then the fact off. Hey, everybody, Sam here. Before we hop back into the episode, I wanted to give a quick little disclaimer. If Deboki's upcoming fact off fact sounds strangely familiar to you, that's because we have covered it on a previous episode. We keep our facts secret from each other

Starting point is 00:21:32 and usually our guests don't write fact-off facts. So this one just kind of slipped through the cracks. We apologize for this. But if you have heard this fact before, maybe Deboki will give you a fresh new perspective on it and you'll still learn something. Okay, thanks. Bye. Welcome back. Deboki and Sam are tied 0-0 because of my devious lies that may or may not have been fair. Who knows? I think they were. But that means we have to get ready for the fact off. Our panelists have both brought science facts to present in an attempt

Starting point is 00:22:12 to blow my mind. It's my turn to judge. And after they've presented their facts, I will judge them and award Sari Bucks any way I see fit. And to decide who goes first, I have a trivia question. Glaucoma, most commonly primary open angle glaucoma, is the leading cause of irreversible blindness in the world. A study published in March 2022 found that the average person without glaucoma has a 97 micrometer thick retinal nerve fiber layer. People with primary open angle glaucoma had thinner retinal nerve fiber layers. So how many micrometers thick were they on average? But it's less than 97 point 45. Deboki wins. The answer is 65.2. How much did she win by?

Starting point is 00:23:12 Eight. Oh, shoot. Yeah, so that's quite a bit thinner, which feels weird to me. And with your great victory, Deboki, would you like to go first or would you want Sam to go first? I'll go first or would you want sam to go first i'll go first so in general nerves are you know kind of fragile they're not super flexible uh if you stretch them too much you might damage some of the fibers inside the nerve you you know that's how you get a stretched nerve injury so there's a lot there that you know you want to be protective of when you when it comes

Starting point is 00:23:42 to nerves and so for our bodies our bodies, that's how they do. They make them not super flexible, so you can't overstretch them much. So all of that is why researchers studying whales in Iceland were very surprised when they grabbed one of the whale nerves and found that was actually very, very stretchy. So this researcher grabbed this three foot long nerve and found that it could stretch to twice its original length. And that when you let it go, it would actually spring back to its original size, kind of like a bungee cord. And the nerve was so stretchy that the scientists studying it thought it was actually a blood vessel at first. But when they cut it open, they realized that the insides were full of nerve fibers instead.

Starting point is 00:24:21 So the nerve came from the jaw of a fin whale, which is a member of the rorquois whale family. I think that's how you say it, rorquois. That's what I found when I looked it up. So these whales are gigantic. These are things like blue whales, humpback whales. So they're these huge whales that to eat will actually do this thing called lunge feeding. So they open their mouths wide and they lunge forward very, very quickly to take in a big gulp of water that they then filter through for food. And so as part of that process, their mouths expand kind of like a balloon to take in a huge volume of water. One of the things I found said that some whales will take in a volume of water that is like their equivalent in size. So there's a lot of expanding that you have to do to make that happen.

Starting point is 00:25:06 And as a result, their tongue and jaw and mouth blubber all have to be pretty flexible to make that all come together and to make them able to inflate like a giant balloon full of water. So that's why having a super stretchy nerve can help because if you are, you know, if you need to be super flexible in this way, it helps if your nerves can stretch along with the rest of your weird stretchy mouth. So when the researchers looked inside the nerves, they found that the nerve fiber themselves are not actually super stretchy. These were just kind of long and curled up inside the nerve. Like in my mind, I kind of see it as like a little bundle of string. But the outer layer of the nerve is made up of stretching materials like the protein elastin. So when you pull on the nerve, that outer layer stretches while the fibers inside kind of unfurl into their full length.

Starting point is 00:25:55 So that's how those nerves are able to do all that stretching. And my favorite part of this story is that basically the reason that they found this is because that scientist was just like picking up this nerve and was basically just like hey look at this and was like stretch like he picked up this like giant whale nerve that they had lying around it's like ah this thing is just stretching look at this thing i can do and then they were all like huh should i be doing that i guess or like is that right and then they that's that's how you find things out i guess do they know anything about like the evolution of these it's like kind of like flexibility where you have to stretch a little bit at a time before you get to ballooning twice your volume the fact that they found this was like super

Starting point is 00:26:37 unique within vertebrates so i don't think there's enough to be able to say just based on like hey we found this happening to be able to piece together the evolution of it. But yeah, I would love to know. Because especially like, you know, like these are giant whales. Like these are like the biggest animals on earth. Like, and this probably is part of how they got that way. But I don't know how you evolve that.

Starting point is 00:27:01 Do all the like, does all the inside stretch too? Or is it just like the outside? It's just the outside. It's just the outside. It's just the inside is really long. So it's able to, like as it's stretching out, all of that is able to take up that space inside the nerve and like kind of unfurl like that. Like if you just have like a little clump of string and then you stretch it all out and it unfurls, I think that's like what's going on inside the nerves. Okay, Sam, what do you got? The human ear. It's chock full of nerves, baby. When sound hits our ear, things vibrate and liquid sloshes around in our cochlea, which in turn activates tens of thousands of nerve endings in the cochlea

Starting point is 00:27:35 that decode those vibrations into signals that get sent into our brains. Thus, the sound is heard and interpreted by the canny human mind. And this is true of basically all vertebrates and even some arthropods. But there are lots of invertebrates out there, your mollusks, your worms, your bugs, that do not have visible ears. So the common idea is that these creatures can't hear in a way that we would recognize as hearing. They can like detect vibrations from the ground, sure, but they don't have ears. So they don't have any of the parts to interpret vibration as sound, right? Well, C. elegans are a little wormy, a very, very little wormy. They're like microscopic wormies, and they have way less nerves than a human, like 302 to our 7 trillion or however many we have, something like that.

Starting point is 00:28:22 But despite that, they exhibit almost all the same senses that we have. They can detect light, they can touch stuff, they can taste stuff, they have proprioception, aka like they can tell their own body position in space. But until recently, it was assumed that they, like all other invertebrate species, could not hear. I mean, they clearly don't have ears, so how could they hear? However, a paper published in September 2022 may have discovered that they're hiding a little hearing secret. So scientists discovered that when

Starting point is 00:28:51 a tone is played towards C. elegans, even in situations where they weren't on a surface that they could respond to surface vibrations through, the worms still would move away from that sound. Upon further inspection, they found that the sound waves vibrated fluid that was inside of the body of sea elegans and that that vibrating fluid activated auditory nerves that covered their skin. So sea elegans don't need all that sophisticated ear stuff because they are in practice a living cochlea and if this turns out to be the case it could open the possibility that there are lots of other wise earless creatures that are using parts of their bodies as cochlea. So you better stop

Starting point is 00:29:30 saying all that mean stuff about clams right in front of them because they might be able to hear you. That's very weird. So they're just an ear. They're just a wiggly little ear guy. They're kind of an ear and a tongue and an eyeball just squished up in a little guy. Do you know if it's, it sounds like it's because they're so like squishy and like the fluid inside is what makes them. Are other animals ears that aren't so like aqueous or wiggly? I think they think it's just squishy guys. That was my understanding of it, but I'm not, I don't know. You love C. elegans, right?

Starting point is 00:30:08 You keep trying to make me do an episode about it. It's true. I do keep trying. Okay. So if listeners, if this makes it into the final cut, please request a C. elegans episode because I feel like they're pretty neat, pretty nifty. They've been involved in a lot of scientific research, but if we don't end up ever doing a C. elegans episode, you can watch Journey to the

Starting point is 00:30:26 Microcosmos, our nematode episode. We talk about C. elegans and why they're such incredible model organisms. What Sam has done is manipulated me into supporting his fact as the winner. That really what I want is for people to respect C. elegans and appreciate this worm and all it's contributed to our scientific knowledge. It's just a little worm. It's nothing to me. Oh, well, Sam. But I still think my stretchy whale nerves are cooler for today. I think I got to go with Sam.

Starting point is 00:31:04 Yeah, I'm just really charmed by these little ears floating around and the fact that they're just... Yeah, maybe they can hear you right now and they're saying, thank you. Thank you, yeah. And just like it really speaks to like the interconnectedness of nerves. Like we don't know what's going on. All of our nerves just used to sense things, and then they've gradually gotten more specific. And now we can go, ouch. Or like, that's soft and nice.

Starting point is 00:31:30 So I'm just going to give two Sari bucks to Sam, one to Deboke, because I liked both your facts. So you both have some currency. Thank you for your labor. She can't get one. Here's your payment. She can't get one, too. It is Sari's bucks to give however she sees fit. And if I get one, then I get one, Sam.

Starting point is 00:31:48 So with that dramatic middle to the episode, I was about to say ending, it's time to ask the science couch, which is still me and Deboki. Where we ask listener questions to our couch of finely honed scientific minds. Oasis on Discord asks, when your arm or your leg goes to sleep and you get the pins and needles paresthesia feeling why does it feel like pins and needles well i'm standing hank but i did the research so yeah i feel like at the beginning of the episode when you were like deboki is replacing me on the science couch that was misleading. I am really just here listening to you. Well, if you're comfortable, do you want to take a stab at it using your vague knowledge of the nervous system and biology? Why you get pins and needles?

Starting point is 00:32:38 Either I feel like it's not a deliberate thing. It's just like there's so much sensation immediately going to it that your body's kind of overwhelmed or it's a way of your body being like oh hey like this thing is not has not been moving or has been like cut off from circulation and like like we're gonna like jam it awake with all of these signals just to be like you know move it that's interesting i just figured it was like the panic default state of nerves just to be like, I can't feel anything. So this is the signal I will send you like television static. you said you like you both said and agreed on which is that it's it's nerve irritation and then they either can't send signals at all because they're like pinched in a weird way or like something is blocking them they're not getting enough blood they're not getting enough nutrients and so they can't do their normal signaling or they're just kind of firing randomly because they

Starting point is 00:33:39 can kind of get out a little a little signal but it's not anything coordinated. So instead of being in a resting state, most of the time, I would say your skin is kind of passively receiving input from the environment, but you're not feeling everything all the time. You're just kind of hanging out. But if you put pressure in a weird way or sit with your arm at a weird angle, then it might fall asleep because you're putting pressure on a nerve. And then as soon as you stop putting pressure, then your nerves like, oh, I'm waking back up and I don't know what to do with all this.

Starting point is 00:34:14 Like I'm just going to like start firing. Yeah. So sometimes when your legs fall asleep, it's like hard to walk or most of the time. Is that just because proprioception is all screwy with it or? That's my guess is that it causes like, so it's like a roadblock and then your nerves need some time to recover to function normally like there's this period of time where they are just not working and either not sending

Starting point is 00:34:37 signals or extra signals and so that needs that readjustment period to start signaling normally and sending your brain the information it needs besides the television static that you're getting at that given time. That's just kind of like, blah, recalibrating. Do we know anything about like what affects how long the feeling is there for? I think a lot of the time when your limb falls asleep, it's like you squeeze the nerve or like the arteries that are bringing blood or the capillaries that are bringing blood. So usually if you're like most people experience this and falling asleep, then it's just a short amount of time, like within seconds or minutes for like that supply

Starting point is 00:35:19 of oxygen and glucose to just get back and reactivate the cells. But non-reversible or permanent kind of paresthesia, then it may never return. Or I think it's part of that we don't understand neurons really, where you can't necessarily regrow when you have nerve damage. So I think there's a fuzzy line between your cells were just kind of deprived and then they can bounce back from that and you're going to feel tingly and bad for a second. And like you did something very bad to your body or your body like shut down for some reason and now your nerves don't work good anymore. So that was a half answer. Well, if modern science doesn't know, you can't expect you to know everything. And if you want to ask the science couch

Starting point is 00:36:06 and have our half-formed answers, follow us on Twitter at SciShowTangents, where we'll tweet out the topics for upcoming episodes every week, or join the SciShowTangents Patreon and ask us on Discord. Sam and I hang out in there sometimes. Thank you to Rith on Discord,

Starting point is 00:36:23 at OobLil, and everybody else who asked us your questions for this episode. Thank you to Boki for joining us. Is there anything that you want to plug? Yeah, so I am on Twitter at at Okidoki underscore Boki. I sometimes post there. But also, if you want to listen to me on another podcast, you can listen to me on Tiny Matters, where me and my co-host Sam Jones, we talk about the small things that matter. We've had episodes about coral reefs, about HIV, typhoid, yeah, just whatever it is that we've been finding interesting and want to learn more about.

Starting point is 00:36:57 So you can find more of me there. If you like the show and you want to help us out, it's really easy to do that. First, you can go to patreon.com slash SciShowTangents to become a patron and get access to things like our newsletter and bonus episodes. Second, leave us a review wherever you listen. It's super helpful and it helps us know what you think about the show or what topics we should cover. If we get a bunch of C elegans, maybe we'll do that. And finally, if you want to show your love for SciShow Tangents, you can just tell people about us. And thank all you listeners for joining us this week. I have been Sari Reilly. I've been Sam Schultz.

Starting point is 00:37:32 And I'm Deboki Chakrabarty. SciShow Tangents is created by all of us and produced by Sam Schultz, who edits a lot of these episodes, along with Seth Glicksman. Our story editor is Alex Billow. Our social media organizer is Paola Garcia Prieto. Our editorial assistants are Deboki Chakravarti and Emma Douster. Our sound design is by Joseph Tuna Medish. Our executive producers are Caitlin Hoffmeister and the very stinky Hank Green. And we couldn't make any of this without our patrons on Patreon. Thank you. And remember, the mind is not a vessel to be filled, but a fire to

Starting point is 00:38:05 be lighted. But one more thing. The sciatic nerve, as we were talking about before, is not just a butt nerve. It's your longest and thickest nerve traveling from your lower back through your hips and butt and down your legs. So a severed sciatic nerve can be pretty detrimental to walking. To help regenerate severed sciatic nerves in rats, a Brazilian research group added a natural latex membrane that bridged the empty space in the nerve. Give a little latex about eight weeks in the rat's butt, and they have the nerve to do better on the treadmill than rats who got the best alternative transplant. They got stretchy butts. They just need to implant a whale nerve in there, and then they'll be super stretchy. I feel like the whale nerves are going to be like

Starting point is 00:39:05 ten times the size of the rat. But yes. They'll figure it out. The scientists will squeeze it in. Yeah. We can 3D print anything

Starting point is 00:39:14 at this point. Yeah. We need rats that are better at running though. It's important.

SciShow Tangents - Nerves

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