WEBVTT - Listener Questions #15 0:00:00.080 --> 0:00:01.960 Hey, they're extraordinaries. Kelly. 0:00:02.000 --> 0:00:05.760 Here my book, A City on Mars? Can we settle Space? 0:00:05.880 --> 0:00:09.080 Should we settle space? And have we really thought this through? 0:00:09.520 --> 0:00:12.959 Comes out in paperback on July twenty ninth, So if 0:00:13.000 --> 0:00:15.520 you've been interested in reading it but the hardback version 0:00:15.680 --> 0:00:18.120 was just too expensive or the wait list at your 0:00:18.160 --> 0:00:22.400 library was intolerably long, then you're in luck. In this 0:00:22.480 --> 0:00:25.520 book we answer questions like where are we likely to 0:00:25.520 --> 0:00:28.840 settle in space? Can we make babies in space? Why 0:00:28.880 --> 0:00:32.159 do astronauts love taco sauce? And what's the legal status 0:00:32.200 --> 0:00:35.239 of space cannibalism? So grab yourself a copy of A 0:00:35.320 --> 0:00:48.800 City on Mars wherever fine books are sold. Conflicting advice 0:00:48.880 --> 0:00:49.920 is making me twitch? 0:00:50.200 --> 0:00:53.280 Is it good or is it bad? To scratch my itch? 0:00:53.840 --> 0:00:57.120 If the ort cloud is filled with icy rocks? Why 0:00:57.280 --> 0:00:59.440 isn't our view of the stars blocked? 0:01:00.040 --> 0:01:06.039 Are honeybees Nature's mathematicians? Or can nature forge hexagons without cognition? 0:01:06.480 --> 0:01:09.280 Whatever questions keep you up at night, Daniel and Kelly's 0:01:09.280 --> 0:01:10.560 answers will make it right. 0:01:11.120 --> 0:01:13.880 Welcome to Daniel and Kelly's Extraordinary Universe. 0:01:27.160 --> 0:01:30.160 Hi, I'm Daniel, I'm a particle physicist and I love 0:01:30.360 --> 0:01:33.920 hearing questions from the public. What people are wondering about, 0:01:33.920 --> 0:01:36.800 what they're curious about, what they are confused about. Right 0:01:36.880 --> 0:01:39.720 to be please and share with me your confusion. 0:01:40.040 --> 0:01:40.360 Hello. 0:01:40.400 --> 0:01:41.360 I'm Kelly Winer Smith. 0:01:41.360 --> 0:01:44.880 I study parasites and space, and I totally agree with Daniel. 0:01:44.920 --> 0:01:47.680 And also I have to note that these questions have 0:01:47.920 --> 0:01:50.760 pointed out to me how many things I don't think 0:01:50.840 --> 0:01:54.080 hard enough about. Like today we have some very basic 0:01:54.200 --> 0:01:57.360 questions about like why do we itch? And I you know, 0:01:57.520 --> 0:02:01.080 I must scratch ten or so times and like, yeah, 0:02:01.160 --> 0:02:03.440 maybe even more without thinking about it. And I've never 0:02:03.480 --> 0:02:06.520 really thought about why. And so I am loving the 0:02:06.560 --> 0:02:09.079 opportunity to dig into all of these different questions. 0:02:09.240 --> 0:02:11.799 Yeah, it's fun on so many levels, Like we get 0:02:11.800 --> 0:02:14.800 an opportunity to learn more about areas that we've always 0:02:14.800 --> 0:02:17.720 been curious about but never had an excuse to dig into, 0:02:17.760 --> 0:02:20.000 Like yeah, when have you told yourself I have an 0:02:20.040 --> 0:02:22.320 hour free, I'm a to read about itching? But now 0:02:22.360 --> 0:02:24.920 you have a reason, right, Yep. You also discover how 0:02:24.960 --> 0:02:28.000 many basic things in science we're still pretty clueless about, 0:02:28.480 --> 0:02:30.520 you know, like how many things we understand at really 0:02:30.639 --> 0:02:33.400 just the surface level. Yeah, which means that there's lots 0:02:33.440 --> 0:02:35.679 of things to figure out for all you young scientists 0:02:35.720 --> 0:02:36.079 out there. 0:02:36.200 --> 0:02:38.239 Yeah, that's right, all the kids who are listening, there's 0:02:38.280 --> 0:02:40.080 a lot of work for you to do, and just 0:02:40.160 --> 0:02:42.440 keep a list as we go through these episodes of 0:02:42.560 --> 0:02:44.720 questions that need answers that you might be the one 0:02:44.720 --> 0:02:45.120 to answer. 0:02:45.320 --> 0:02:47.840 That's right. The forefront of human knowledge is not that 0:02:48.000 --> 0:02:50.600 far away from where you are right now in lots 0:02:50.639 --> 0:02:53.200 of cases. I mean, yeah, we've been doing physics for 0:02:53.240 --> 0:02:55.120 a long time and we've made some progress, and it 0:02:55.160 --> 0:02:58.720 takes a while to understand all the details of particle physics, 0:02:58.720 --> 0:03:01.800 but they're still very basic questions even about particle physics, 0:03:01.840 --> 0:03:04.079 that we don't know the answers to. Why are there 0:03:04.120 --> 0:03:06.320 so many particles? What do they all do? What is 0:03:06.360 --> 0:03:08.080 the rest of the universe made out of? You know, 0:03:08.400 --> 0:03:11.200 basic stuff everybody wants to understand. And so if you 0:03:11.240 --> 0:03:13.840 have a question about the universe or parasites or parasites 0:03:13.880 --> 0:03:16.679 in the universe, you might be asking a question right 0:03:16.680 --> 0:03:19.840 at the forefront of our knowledge. So don't be shy, ask. 0:03:19.600 --> 0:03:23.400 Away and let us do the research for you. So 0:03:23.639 --> 0:03:26.240 I have an answer I'm just itching to share with you. 0:03:27.120 --> 0:03:30.840 We got we got there must have been something itchy 0:03:31.000 --> 0:03:33.320 in the air, because within a very short amount of 0:03:33.360 --> 0:03:36.960 time we got two different questions about itching and scratching. 0:03:37.040 --> 0:03:39.600 So let's go ahead and hear the questions. 0:03:39.960 --> 0:03:43.000 I'd like to know what causes itches and why does 0:03:43.000 --> 0:03:46.440 scratching stop them. I don't mean itches that have a 0:03:46.520 --> 0:03:52.760 clear source medicine, side effects, bug bites, rashes, irritating clothing scenes, 0:03:52.800 --> 0:03:55.480 et cetera. I mean when you're just going about your 0:03:55.560 --> 0:03:58.760 day and suddenly some random part of you itches. How 0:03:58.800 --> 0:04:00.520 will you scratch it the itch stops? 0:04:00.720 --> 0:04:04.920 What's up with that? Hey, I'm loving the show. I 0:04:04.960 --> 0:04:07.080 wonder if you could answer a question for me. This 0:04:07.240 --> 0:04:10.680 might be one for Kelly. I've heard recently about a 0:04:10.760 --> 0:04:14.000 study which said, I think it was in mice, that 0:04:14.120 --> 0:04:17.360 if you scratch an itch, then it's beneficial because that 0:04:18.360 --> 0:04:22.039 allows antibodies to go to the site and to clear 0:04:22.120 --> 0:04:25.640 up any infection. But then there was another study, also 0:04:25.800 --> 0:04:30.000 in mice, saying that scratching and itch is problematic because 0:04:30.040 --> 0:04:33.760 it activates pain nerves, which then causes more riching and 0:04:33.800 --> 0:04:38.360 more inflammation. Which is it, Should I ignore the urge 0:04:38.400 --> 0:04:41.039 to scratch an itch or should I just go ahead 0:04:41.040 --> 0:04:44.920 and scratch it. Keep up the good work. Thanks. 0:04:45.200 --> 0:04:47.200 I think these questions are pretty deep. They're not really 0:04:47.240 --> 0:04:49.800 just surface level, you know. I think they're really dig 0:04:49.960 --> 0:04:53.599 down into what's going on. I didn't eat the skin, yeah. 0:04:53.600 --> 0:04:55.159 And I had a ton of fun digging in. 0:04:55.200 --> 0:04:58.200 And actually, it turns out that our understanding of itching 0:04:58.720 --> 0:05:02.120 has apparently undergone some pretty major changes in the last 0:05:02.120 --> 0:05:06.960 few decades. So initially we thought that itching was a 0:05:07.120 --> 0:05:10.560 minor form of pain, which would suggest that it's using 0:05:10.680 --> 0:05:14.000 the same pain receptors. And it's just sort of like, 0:05:14.080 --> 0:05:16.400 if you tickle the pain receptors just a little bit, 0:05:16.440 --> 0:05:18.760 you get an itch, but when you really hurt them, 0:05:18.800 --> 0:05:19.520 then you get pain. 0:05:19.640 --> 0:05:21.400 But back up and give me the bigger picture here. 0:05:21.400 --> 0:05:24.479 When you say pain receptors, you're talking about like nerve 0:05:24.600 --> 0:05:27.320 endings just under the skin. And I don't know enough 0:05:27.360 --> 0:05:30.120 biology to even know, like, are there different nerves for 0:05:30.240 --> 0:05:32.920 pain and for like cold and for other stuff? How 0:05:32.920 --> 0:05:33.719 does that all work? 0:05:33.960 --> 0:05:35.039 Oh? Yeah, great questions. 0:05:35.080 --> 0:05:37.320 So there are different nerves for different things, and so 0:05:37.360 --> 0:05:40.680 we do have some nerves that specifically are there to 0:05:40.800 --> 0:05:42.880 tell us about pain. And so for anyone who's gotten 0:05:42.880 --> 0:05:45.280 tattoos out there, you know, that there are some areas 0:05:45.320 --> 0:05:48.200 that hurt to get tattooed more than others. Daniel, you're 0:05:48.240 --> 0:05:51.000 shaking your head, yes, knowingly. Do you have tattoos? 0:05:51.360 --> 0:05:54.280 I do not, but I have a teenager who wants 0:05:54.320 --> 0:05:57.279 to get tattoos, and so we've had lots of conversations 0:05:57.920 --> 0:06:00.000 about making ferman decisions for your body. 0:06:00.240 --> 0:06:01.000 Got it okay. 0:06:01.200 --> 0:06:02.680 So there are some parts of your body that have 0:06:02.720 --> 0:06:05.640 more pain receptors than others, and those areas tend to 0:06:05.720 --> 0:06:07.880 hurt a little bit more when you get tattoos. And 0:06:07.960 --> 0:06:11.320 what these receptors do is they deliver messages from like 0:06:11.360 --> 0:06:14.320 the surface of your skin up to your brain to say, oh, 0:06:14.400 --> 0:06:16.919 something hurts, and then you respond to it, and often 0:06:16.920 --> 0:06:19.120 you respond to it without even really thinking about it. 0:06:19.160 --> 0:06:20.800 You have sort of a reflexive response. 0:06:20.960 --> 0:06:22.599 And so, for example, I know that I have a 0:06:22.640 --> 0:06:25.520 lot of nerves and the tips of my fingers, so 0:06:25.520 --> 0:06:27.320 I could tell the difference between one needle and like 0:06:27.360 --> 0:06:29.800 two needles very close together, and the tips of my 0:06:29.839 --> 0:06:32.279 finger has been not like on my elbow because I 0:06:32.279 --> 0:06:34.960 have fewer nerves there. I can't resolve it. But that's 0:06:34.960 --> 0:06:37.400 a different nerve system than the ones that help me 0:06:37.440 --> 0:06:38.000 sense pain. 0:06:38.240 --> 0:06:39.960 Yeah, so we're getting a little bit outside of my 0:06:40.040 --> 0:06:42.000 area of expertise here, but I think that those are 0:06:42.080 --> 0:06:45.520 touch receptors that you would be detecting there, unless you 0:06:45.560 --> 0:06:48.479 were like stabbing those needles into your fingers, which I 0:06:48.520 --> 0:06:51.400 assume you're not. I think we're talking about touch receptors there, 0:06:51.400 --> 0:06:53.279 and we've got receptors for cold and for hot and 0:06:53.320 --> 0:06:53.920 stuff like that. 0:06:54.000 --> 0:06:56.080 So you were saying that people used to think that 0:06:56.240 --> 0:07:00.479 itching or stimulating the pain receptors the nerves that when 0:07:00.480 --> 0:07:02.400 something hurts, Yeah, that doesn't really make a lot of 0:07:02.400 --> 0:07:04.640 sense to me, because itching doesn't feel like pain. It 0:07:04.640 --> 0:07:08.080 feels like uncomfortable and enjoys me crazy, but doesn't hurt 0:07:08.080 --> 0:07:08.680 the same way. 0:07:08.920 --> 0:07:09.120 Yeah. 0:07:09.160 --> 0:07:12.440 Well, so I wonder if it was because sometimes if 0:07:12.480 --> 0:07:14.400 you itch for a really long time, you scratch and 0:07:14.440 --> 0:07:16.400 then it starts to hurt. And so maybe people were 0:07:16.440 --> 0:07:20.440 just like imagining a continuum there that doesn't exist. But also, 0:07:20.520 --> 0:07:23.480 it's not so surprising we got these two systems sort 0:07:23.480 --> 0:07:25.880 of mixed up because they have a lot of cross talk. 0:07:26.280 --> 0:07:29.480 There's a lot of times when you stimulate one system 0:07:29.520 --> 0:07:32.040 and it sort of interacts with the other. For example, 0:07:32.480 --> 0:07:35.760 when I got an epidural when I was pregnant with 0:07:35.840 --> 0:07:37.800 my second. The first one was natural, second one, I 0:07:37.800 --> 0:07:38.520 had an epidural. 0:07:38.840 --> 0:07:40.800 Uh not just like a Friday night epidural. 0:07:40.960 --> 0:07:44.120 No, yeah right, No, I mean fun not recreational. 0:07:44.320 --> 0:07:45.000 Recreational. 0:07:45.120 --> 0:07:48.840 Yeah, no judgments to anybody out there who does that, 0:07:48.880 --> 0:07:50.120 you know, just clarifying here. 0:07:50.280 --> 0:07:52.440 Yeah, fair enough, But that would be an expensive habit, 0:07:52.440 --> 0:07:54.720 I'm guessing, because I think you'd need to get insured. 0:07:55.120 --> 0:07:59.320 But anyway, so when I got my epidural, I started 0:07:59.680 --> 0:08:01.080 itching like crazy. 0:08:01.320 --> 0:08:02.840 And I didn't. 0:08:02.560 --> 0:08:04.960 Find like a paper that specifically said some people who 0:08:05.000 --> 0:08:06.200 get epidural. 0:08:05.720 --> 0:08:06.720 Scratch like crazy. 0:08:06.880 --> 0:08:09.120 But I found a couple of papers that were referencing 0:08:09.160 --> 0:08:12.720 how sometimes when you do something for pain, you get 0:08:12.720 --> 0:08:14.880 this weird itchy side effect, and sometimes when you do 0:08:14.960 --> 0:08:17.400 something for itching, you get this weird pain side effect. 0:08:17.640 --> 0:08:19.680 And so these two systems seem to have a lot 0:08:19.680 --> 0:08:22.800 of cross talk, and they interact, but they are separate. Interesting, 0:08:23.000 --> 0:08:25.920 and so we do have specific receptors for itch. 0:08:26.200 --> 0:08:29.280 We do, so we've like evolved a whole system to 0:08:29.440 --> 0:08:30.600 make you uncomfortable. 0:08:30.920 --> 0:08:32.520 Well, okay, so I would say that a lot of 0:08:32.559 --> 0:08:36.320 times it does seem like our itch system does things 0:08:36.320 --> 0:08:38.599 that are maladaptive. Give me a second to do a 0:08:38.600 --> 0:08:40.640 little bit more explaining, and then we'll get back to that. 0:08:40.840 --> 0:08:43.480 So you've got these itch receptors and they can be 0:08:43.640 --> 0:08:48.760 stimulated externally or internally. So externally would be like there's 0:08:48.800 --> 0:08:52.720 a tick crawling on your skin and you feel itchy, 0:08:52.840 --> 0:08:55.400 and your immediate response is to try to brush it off, 0:08:55.840 --> 0:08:59.400 and that is pretty adaptive. You know, you move it off, 0:08:59.520 --> 0:09:01.480 and now you don't have that tick on there anymore. 0:09:01.640 --> 0:09:03.960 And I'm very proud of my body because I feel 0:09:03.960 --> 0:09:06.960 like I am really tuned to ticks. I've almost never 0:09:07.000 --> 0:09:09.320 had one bite me, but I've taken loads off of me, 0:09:09.400 --> 0:09:11.080 so like I feel them when they're moving around, So 0:09:11.120 --> 0:09:11.560 that's good. 0:09:11.679 --> 0:09:14.600 That's definitely a plus. I understand that, like your body 0:09:14.679 --> 0:09:18.360 wants you to feel uncomfortable having that critter crawl over you. 0:09:18.440 --> 0:09:20.839 Yes, exactly, Like your attention needs to be drawn to 0:09:20.920 --> 0:09:22.320 that you need to take care of it right away. 0:09:23.040 --> 0:09:29.040 We also have responses to internal things like histamines and 0:09:29.160 --> 0:09:32.160 various things that your immune system does. So for example, 0:09:32.240 --> 0:09:35.120 if you in the winter have really dry hands and 0:09:35.160 --> 0:09:37.480 you like make a fist and your skin cracks and 0:09:37.520 --> 0:09:41.520 bleeds like mine does, your immune system responds to those 0:09:41.520 --> 0:09:45.160 cracks and it recruits to where those cracks are, and 0:09:45.200 --> 0:09:50.440 the presence of those immune system cells trigger your itch receptors. 0:09:50.480 --> 0:09:52.920 And that's why your hand gets itchy when it's all 0:09:52.960 --> 0:09:53.840 broken and bleeding. 0:09:54.120 --> 0:09:58.240 Help me understand why internal histamines trigger the same receptors 0:09:58.280 --> 0:10:02.040 as a tick crawling across myself. Does that make sense. 0:10:01.800 --> 0:10:04.520 For some reason, I'm not sure that it does make sense. 0:10:05.120 --> 0:10:09.360 So there's a couple of different hypotheses here. So one 0:10:09.520 --> 0:10:14.800 hypothesis is that our species itches as. 0:10:14.679 --> 0:10:16.880 Sort of like an evolutionary hold over. 0:10:17.160 --> 0:10:19.480 So we used to have fur, and it used to 0:10:19.480 --> 0:10:21.320 be that we would when we would itch, we wouldn't 0:10:21.400 --> 0:10:24.480 damage ourselves because the fur got in the way. But 0:10:24.520 --> 0:10:26.280 now we don't have fur, and so when we itch, 0:10:26.320 --> 0:10:28.520 we damage ourselves. And so it could be that most 0:10:28.559 --> 0:10:32.040 of the time when there was an immune response, maybe 0:10:32.040 --> 0:10:34.160 it was because, for example, there was a tick that 0:10:34.320 --> 0:10:37.160 had bit and the immune system was responding to it. 0:10:37.400 --> 0:10:39.480 And so if you scratch, and you scratch through your fur, 0:10:39.559 --> 0:10:41.840 you get that tick off. And you know, I can 0:10:41.880 --> 0:10:45.480 still imagine the immune system drawing your attention to the 0:10:45.480 --> 0:10:47.480 presence of a tick, and you know, the sooner you 0:10:47.559 --> 0:10:49.520 remove a tick, the better, because some of them don't 0:10:49.679 --> 0:10:51.760 give you the diseases they're carrying until they've been on 0:10:51.800 --> 0:10:54.200 there for a while. And now I feel like I'm 0:10:54.240 --> 0:10:56.080 crawling with ticks because we're talking about it. 0:10:56.559 --> 0:10:59.400 I hope everybody out there getting itchy and ticky. 0:10:59.440 --> 0:11:03.280 Yes, guys and gals, So yeah, I mean I think it. 0:11:03.520 --> 0:11:07.079 Sometimes scratching is good because it removes something, or maybe 0:11:07.080 --> 0:11:08.600 it recruits more immune cells. 0:11:09.040 --> 0:11:10.679 But sometimes scratching is just bad. 0:11:10.760 --> 0:11:12.800 So I think you're saying that itching on the surface 0:11:13.559 --> 0:11:16.120 is very clear. It's to help us get rid of 0:11:16.160 --> 0:11:18.280 something that's crawling across us and might bite us and 0:11:18.400 --> 0:11:21.760 is bad for us, And that itching internally might also 0:11:21.840 --> 0:11:24.760 be good because it's a signal that something is already 0:11:24.760 --> 0:11:27.160 bitten us, and if we scratch it, we could get 0:11:27.240 --> 0:11:30.240 rid of it. So it's not that they trigger exactly 0:11:30.320 --> 0:11:32.520 the same mechanism. It's like two ways to protect us 0:11:32.520 --> 0:11:35.960 from critters. But are they biochemically the same mechanism, Like 0:11:36.280 --> 0:11:39.120 does it tick crawling across your skin trigger the same 0:11:39.240 --> 0:11:42.120 histamines and that whole same channel, or are they two separate. 0:11:41.800 --> 0:11:46.640 Mechanisms Both mechanisms trigger the same itch receptors to send 0:11:46.640 --> 0:11:49.160 a message to your brain that says scratch. And I 0:11:49.160 --> 0:11:52.120 think in both cases you can get good information that 0:11:52.200 --> 0:11:54.959 tells you to scratch when you should scratch, but both 0:11:55.040 --> 0:11:58.440 externally and internally you can also get bad information. So, 0:11:58.480 --> 0:12:02.080 for example, your skin might be particularly sensitive to certain 0:12:02.160 --> 0:12:05.240 kinds of allergens, or you know, certain kinds of compounds 0:12:05.240 --> 0:12:07.440 and soap, right, and then you might start scratching for 0:12:07.480 --> 0:12:10.160 no good reason. And you know, same thing with your 0:12:10.240 --> 0:12:14.200 body responding internally by releasing histamines at places where you 0:12:14.240 --> 0:12:17.040 really don't need to be scratching. And additionally, when you 0:12:17.080 --> 0:12:21.280 start scratching, you can initiate what's called the itch scratch cycle. 0:12:21.760 --> 0:12:23.000 And here's what happens there. 0:12:23.040 --> 0:12:24.439 So this sounds like a nightmare. 0:12:24.640 --> 0:12:27.400 So you start itching, and when you start itching, we 0:12:27.520 --> 0:12:31.920 all know that it feels amazing often, and so what's 0:12:32.000 --> 0:12:36.439 happening there is that your itch signal is being overridden 0:12:36.520 --> 0:12:39.200 by a pain signal, because when you scratch, you're causing 0:12:39.200 --> 0:12:42.200 yourself a little bit of pain. And I think the 0:12:42.240 --> 0:12:44.840 rest of this explanation is a little bit like, here's 0:12:44.840 --> 0:12:46.439 what we think is happening, but we're not one hundred 0:12:46.440 --> 0:12:48.920 percent sure. But they think that after you scratch and 0:12:48.960 --> 0:12:52.640 your pain signal overrides the itch signal, you also release 0:12:52.760 --> 0:12:56.200 some serotonin, which makes you feel better and sort of 0:12:56.200 --> 0:13:00.240 makes the pain eventually go away. And so scratching feels good. 0:13:00.640 --> 0:13:03.199 But when you scratch, you often damage the skin a 0:13:03.240 --> 0:13:06.040 little bit, especially if you're giving it a really strong scratch. 0:13:06.120 --> 0:13:08.360 And if you give it too hard of a scratch, 0:13:08.720 --> 0:13:12.800 now you've caused damage, and that damage recruits more immune cells, 0:13:12.840 --> 0:13:16.840 which makes you itch even more. And so by itching, 0:13:17.080 --> 0:13:20.000 you can make yourself itchier. And so there are people 0:13:20.000 --> 0:13:24.040 who have chronic itching issues and they get stuck in 0:13:24.040 --> 0:13:26.280 this itch scratch cycle. You know, if you tell someone 0:13:26.320 --> 0:13:29.240 who's itchy, oh, just don't scratch it. The scratching is 0:13:29.280 --> 0:13:32.680 what's causing the problem. That's like maddening, I think to 0:13:32.679 --> 0:13:34.520 tell someone because once you've got an itch, how do 0:13:34.559 --> 0:13:36.040 you avoid scratching that itch? 0:13:36.120 --> 0:13:37.439 That's like all you can think about. 0:13:37.720 --> 0:13:40.200 This is fascinating to me to understand exactly what happens 0:13:40.200 --> 0:13:41.959 when you scratch an itch, because I do this all 0:13:42.000 --> 0:13:44.440 the time. I'm the kind of person who's very sensitive 0:13:44.480 --> 0:13:47.920 to mosquito bites. They like torture me, and if I 0:13:47.960 --> 0:13:50.400 have one that's like really buzzing, and I scratch it. 0:13:50.400 --> 0:13:53.560 It's like the greatest relief in the world. Oh my god, 0:13:53.559 --> 0:13:55.720 that feeling is just like it's not just that the 0:13:55.760 --> 0:13:59.880 itch goes away, like actually feels really good, but you're right, 0:14:00.080 --> 0:14:03.040 scratch it hard, then that really fades, and then the 0:14:03.080 --> 0:14:05.720 pain comes through and then it gets itchy again. And 0:14:05.800 --> 0:14:08.640 scattered through my house are like dozens of these itch 0:14:08.679 --> 0:14:11.400 relief sticks, oh, which I totally rely on, and their 0:14:11.520 --> 0:14:15.000 lile benagyl sticks, and they are antihistamines. So I think 0:14:15.240 --> 0:14:18.679 that personal piece of data that the anecdote supports your 0:14:18.720 --> 0:14:21.920 hypothesis there. But it's fascinating to hear about like the serotonin, 0:14:22.000 --> 0:14:23.960 Like that's why I feel good, Right, It's not just 0:14:24.320 --> 0:14:26.680 that the itch has stopped and the discomfort has gone, 0:14:26.920 --> 0:14:28.960 but there's something in my body that is making me 0:14:29.000 --> 0:14:29.880 actually enjoy it. 0:14:30.080 --> 0:14:32.240 That is the current hypothesis. Yes, I don't know that 0:14:32.280 --> 0:14:34.720 we've absolutely nailed that down. And it's interesting that you 0:14:34.800 --> 0:14:39.120 mentioned antihistamines because one of the reasons that we know 0:14:39.280 --> 0:14:42.640 we don't really understand itch well is that you can 0:14:42.720 --> 0:14:45.360 give somewhat antihistamines in a case where you think that 0:14:45.400 --> 0:14:48.360 should solve the problem. Yeah, and it doesn't, and so 0:14:48.720 --> 0:14:51.440 it is more complicated. And you know, for some people, 0:14:51.440 --> 0:14:53.760 if you've got an itch, you scratch it, that's the 0:14:53.880 --> 0:14:55.840 end of the story. But for other people, their immune 0:14:55.840 --> 0:14:58.400 systems are a little bit more sensitive. You scratch it, 0:14:58.520 --> 0:15:00.920 that recruits more immune cells and you start getting in 0:15:00.960 --> 0:15:04.080 the cycle. You also can get chronic itch for reasons 0:15:04.080 --> 0:15:06.120 that you know, we again don't understand really well. 0:15:06.200 --> 0:15:07.640 So, for example, chronic itch. 0:15:08.080 --> 0:15:09.160 I know chronic itch. 0:15:09.240 --> 0:15:10.920 I would never wish that on my worst enemy. 0:15:11.040 --> 0:15:13.760 I was listening to an interview on NPR's Fresh Air 0:15:13.960 --> 0:15:17.160 from a woman who has a disease. I think it 0:15:17.240 --> 0:15:21.080 was of her liver or kidneys, and it creates chronic itch. 0:15:21.120 --> 0:15:23.960 And we don't understand why that particular issue should result 0:15:23.960 --> 0:15:26.960 in chronic itch, but she itches all the time. There's 0:15:27.120 --> 0:15:32.240 also folks who have chronic itch related to mental health issues, 0:15:32.520 --> 0:15:35.000 so like when they get depressed or anxious, it kind 0:15:35.040 --> 0:15:37.080 of makes them itchy, and so they scratch. 0:15:36.720 --> 0:15:37.240 A lot more. 0:15:37.480 --> 0:15:39.920 What's the connection there, I don't think we know. Just 0:15:39.960 --> 0:15:43.480 another amazing mind body connection. You know, it's incredible to 0:15:43.520 --> 0:15:47.320 me how much your mental state influences your body's health. 0:15:47.360 --> 0:15:48.120 And vice versa. 0:15:48.200 --> 0:15:49.800 Yeah, I mean the only reason I ended up on 0:15:49.840 --> 0:15:52.160 anxiety medication is because I went to my doctor and 0:15:52.320 --> 0:15:56.560 was like, everything hurts, my stomach hurts, and why is it? 0:15:56.600 --> 0:15:59.440 And she was like, I think it's uh, you know. 0:15:59.520 --> 0:16:00.920 She didn't say I think it's in your head. She 0:16:00.960 --> 0:16:03.640 was much nicer about it. But yes, when we're stressed 0:16:03.640 --> 0:16:06.080 out or anxious or depressed, it impacts our body in 0:16:06.080 --> 0:16:09.320 weird ways. So yeah, the studying of chronic itching and 0:16:09.360 --> 0:16:12.200 how to relieve it is a big area where there's 0:16:12.240 --> 0:16:13.960 a lot of work that we still have left to do. 0:16:14.600 --> 0:16:17.480 So the first question that we had was why do 0:16:17.600 --> 0:16:21.480 you itch when there's nothing there to make you itch? 0:16:22.000 --> 0:16:24.240 And I think part of the answer could be that, 0:16:24.360 --> 0:16:26.720 you know, for some people it's a mental health thing. 0:16:26.920 --> 0:16:29.280 Maybe they're anxious and stressed and there is nothing there. 0:16:29.760 --> 0:16:32.600 But I think a lot of the times it's something 0:16:32.760 --> 0:16:36.120 did cause you to need to itch, But maybe it's 0:16:36.280 --> 0:16:39.600 just escaping your consciousness. So for example, maybe there's like 0:16:40.080 --> 0:16:43.640 some fiber in your shirt that your body is confusing 0:16:43.800 --> 0:16:46.680 as a tick, or there was something in your soap 0:16:46.760 --> 0:16:48.840 that's creating a little bit of an allergic reaction in 0:16:48.880 --> 0:16:49.280 your back. 0:16:49.320 --> 0:16:50.440 That you didn't know about. 0:16:50.840 --> 0:16:54.120 You know, I think in general, something usually initiates this 0:16:54.240 --> 0:16:57.240 need to scratch, but we just can't always tell what 0:16:57.280 --> 0:16:57.600 it was. 0:16:58.120 --> 0:17:00.200 And the second question I think is one that's to 0:17:00.240 --> 0:17:02.080 my heart, which is, tell me, Kelly, from the point 0:17:02.080 --> 0:17:04.880 of view of science, should I scratch or should I resist? 0:17:04.920 --> 0:17:07.760 Am I a bad person for scratching my itches? All? 0:17:07.840 --> 0:17:08.040 Right? 0:17:08.080 --> 0:17:10.639 One, you are not a bad person for scratching your itches. 0:17:10.680 --> 0:17:12.440 There is no judgment here U. 0:17:13.280 --> 0:17:13.520 Two. 0:17:13.920 --> 0:17:16.679 I think it depends on why you're itching. So the 0:17:16.720 --> 0:17:19.280 listener mentioned that there was a study in mice that 0:17:19.359 --> 0:17:22.320 found that if you scratched, it recruited immune cells to 0:17:22.400 --> 0:17:24.720 the area, and that maybe that immune cell helped you 0:17:25.000 --> 0:17:28.280 deal with an infection or something. So it's possible that 0:17:28.400 --> 0:17:32.280 under some conditions, maybe you're able to recruit more immune 0:17:32.440 --> 0:17:35.560 cells if you've got like an infection or something that's itchy. 0:17:36.080 --> 0:17:39.320 But I think in a lot of cases, itching will 0:17:39.320 --> 0:17:42.800 feel good, but there's some chance that something bad will 0:17:42.800 --> 0:17:44.920 happen afterwards, and that something bad would be you could 0:17:44.960 --> 0:17:47.159 maybe open up a wound and give yourself an infection, 0:17:47.359 --> 0:17:49.040 or you could start off a new round of the 0:17:49.080 --> 0:17:51.920 itch scratch cycle, and so well, I think there's nothing 0:17:52.000 --> 0:17:55.280 wrong with like giving a light scratch to a mosquito bite, 0:17:55.400 --> 0:17:57.200 or if you've got an itch, making sure you don't 0:17:57.240 --> 0:18:00.000 have an insect crawling on you or tick crawling on you. 0:18:00.240 --> 0:18:02.800 But in general, I think the answer, because it's biology, 0:18:03.200 --> 0:18:06.520 is it depends. And if you are going to scratch, 0:18:06.600 --> 0:18:08.719 if you can scratch with like I don't know, your 0:18:08.800 --> 0:18:12.119 knuckles or something to try to like not break the 0:18:12.160 --> 0:18:14.359 skin so much, that would be great. But you know, 0:18:14.600 --> 0:18:16.120 just at the end of the day, some of us 0:18:16.480 --> 0:18:19.880 we can't help but scratch, and it's it's just hard 0:18:19.920 --> 0:18:20.440 to avoid. 0:18:20.760 --> 0:18:22.560 All right. Well, now I have a question which you 0:18:22.640 --> 0:18:25.560 may be the only person in the world qualified to answer. 0:18:25.800 --> 0:18:30.280 What because it connects itches in space? Are there cases 0:18:30.359 --> 0:18:34.040 where astronauts had crazy itches they couldn't scratch because they 0:18:34.040 --> 0:18:36.320 were in a space suit? And what are you supposed 0:18:36.320 --> 0:18:36.600 to do? 0:18:36.960 --> 0:18:40.399 Oh, oh my gosh, that must have happened. 0:18:40.680 --> 0:18:42.360 So you know, you can, like I guess you could 0:18:42.400 --> 0:18:45.159 try to like rub your skin against the inside of 0:18:45.200 --> 0:18:45.600 the suit. 0:18:45.800 --> 0:18:47.960