Magic mushrooms, hiccup rhythms and meteorites

Added: 2026-05-28

[00:00:00]This is a triple-J podcast.

[00:00:02]>> Hello, welcome to another episode of Science with Dr. Karl in your podcast feed. This week we meet Aaron from Wollongong who is studying for an exam in a couple weeks time. She texted in wanting to know a little bit more about her subject matter when it came to a particular question in psychology.

[00:00:18]That's where Dr. Karl comes in. Plus, we talk meteorites, muscle building, space junk, and plenty more. I'm Lucy Smith, let's get into it.

[00:00:28]What does that mean, Dr. Karl, when you kind of hit the wall when you run out of ideas and you it literally feels like your brain's just hit a wall?

[00:00:35]>> It comes, I think, I'm not sure, from uh the popularity in running where people would go for a run and then they gradually work their way up and this is back in the old days. And back then there were very few people who actually did long-distance running apart from professional athletes. And running and jogging came in and people suddenly realized that they could run for 4 km or 5 and then when they went to 6 they had nothing. They were just totally out of energy and the metaphor came in of hitting the wall. If somebody can probably possibly give me a better origin on that term, um please ring on 0439757555.

[00:01:10]>> So, you no longer hit a wall with the triple-J text sign.

[00:01:13]>> No, I still haven't got a good way of remembering the 0439.

[00:01:16]Four is a square and three then leads to three squared which is nine. Kind of weak, getting closer, we'll get something.

[00:01:24]>> I like that. You got your way of remembering things.

[00:01:27]>> have different ways of trying to work out little hooks. And memory's one of these weird things that actually defines who you are cuz without your memories, you're no longer you. And this can be very distressing for people with their relatives or people with Alzheimer's disease where they suddenly don't recognize their daughter or son. That's that's scary.

[00:01:43]Okay, onwards.

[00:01:44]>> Let's stay on the brain, okay? We've got Xander in Newcastle here. Xander, what's your question for Dr. Karl?

[00:01:52]>> Hey, I was just wondering what magic mushrooms do to the brain.

[00:01:55]>> Uh there's a whole bunch of articles on that in the Scientific American and you can download them for free online.

[00:02:01]Scientific American. And what we see is a whole bunch of and they've done MRI scans and functional MRI scans, we see flooding of waves of electrical activity and metabolic activity across the brain.

[00:02:13]But going from that to saying, "Oh, you're taking this sort of hallucinogenic or that." We haven't been able to do that. And also working out why you've got this sudden insight that the universe smells of turpentine.

[00:02:26]And why why why why did insight come flooding into your brain? You know, you don't know. So we the we definitely do not know what they do to your brain. They have been thought to be able to help in some cases of PTSD and I that's post-traumatic stress disorder.

[00:02:43]And we're not too sure exactly why it helps, but it does for some people, but not everybody, help.

[00:02:50]Sorry.

[00:02:51]Got a better answer?

[00:02:53]>> No, well, we've gotten a text from someone saying, "I know a lot of people microdosing for anxiety and depression right now. Have heard they help brain entropy and new neural pathways."

[00:03:03]>> That can help. So we've just actually been mapping the human brain. There was a study that came out last year where they looked at the MRI scans of people of various ages and they found that you start off being relatively inefficient from naught to nine with your brain, but you're making all sorts of connections all over the place and then you gradually shift over to being more efficient, but less widespread. And then as you go through life, you then start at at later stages going to something like an airport hub. So if you want to go from say, I don't know, Toowoomba to Broken Hill, you have to go into either Brisbane or Sydney and you see you've got to use the hubs. And in your early days, you can make connections all over the place, but in the later days, you tend to have to go through hubs. So we're gradually learning about the brain. Watch this space. I'm sorry, Zada. You've asked one of the big ones to start off the show with, Dr. Zanda. How could you do that to us, but we still love you anyway.

[00:03:56]>> Yeah.

[00:03:57]>> Thanks, Dr. Zanda.

[00:03:59]>> Sorry if you're American, he's your friend. Read those articles.

[00:04:01]>> All right, we've got Mark and Cherry book. Now, Mark, last week we were talking about how the brain uses the food that we eat to fuel itself. You have a question following on from that.

[00:04:10]What do you want to know?

[00:04:12]>> I do. Good morning, doctors.

[00:04:14]Um last week you were saying how 80% of the energy you consume goes to your brain and how important carbs were and I wanted to ask how keto impacts your brain function then because um I I jumped on the keto bandwagon many years ago and I dropped about 30 kilos in 6 months.

[00:04:33]>> Oh, it can work for some people. So, >> Yeah, it works, but less than 20 g of carbs a day. So, >> Okay, so um the numbers with regard to your brain function, the average adult, the brain weighs 2% of their body weight, uses 20% of their glucose or energy.

[00:04:48]Um in a 4-year-old, it's 50% and in the 8- to 12-year-olds, it's about 30%. So, it's not 80%, but it's still a huge amount to be used. With regard to glucose, it responds very rapidly.

[00:05:02]Uh the levels can go up and down and the brain can um crank up its activity and then use more glucose and you can release more glucose. With you dealing with the ketones, they're more steady state. So, the brain will run on either glucose or the ketones, which are beu- uh what is it? Aceto- acetyl-hydroxybutyrate, but they're more steady and long term.

[00:05:24]And they will cross the blood-brain barrier. And there was a case of a man who was 105 kg overweight and lost 2.2 kg a week for 54 weeks and didn't eat anything. And his brain ran entirely on ketones. And so, he There was regard to the mental clarity thing. In the early days, often people have a kind of a fog, but then afterwards, they uh they get back to normal or they say, "I've got increased clarity." And that could be related to either there is increased clarity or the placebo effect or they're feeling really good about themselves cuz they've lost some weight. Long-term, you've got this steady energy, but if you've got to throw in a whole lot of resources all at once, you might be just a little tiny bit slow in responding cuz you can throw in more glucose, but you can't throw in ketones really quickly. Um and then uh by the way, the ketones are used medically for childhood epilepsy.

[00:06:18]And the fact that they work really well in some cases of childhood epilepsy does not mean that they work for general day-to-day stuff in adults. And there can be some uh problems with it. So, you can in some people they can have high cholesterol levels um coming out of that. Um and also they can uh with people with diabetes, um they need to be medically supervised to make sure everything's going on. And also a very low-carb diet can influence your gut microbiota and thyroid hormones, but in general you can get away with it in most cases, but you got to make sure that you still keep some carbs coming in.

[00:06:57]>> Yes, it was very Look, thank you, but it was very difficult to maintain, but yes, 4 days of fog every time you want to get into keto.

[00:07:05]>> Oh, so for you the initial fog lasted a a few days, did it?

[00:07:09]>> Yeah, and even if you have one cheat day and eat lots of carbs, then it's another 4 days of to get back to feeling quite energized and good.

[00:07:18]>> Okay, look, I'll just finally finish off by deferring to um a good friend from Newcastle, Clare Collins, and she says you can get away with it, but you're better off having a regular diet. And I won't say any more. We'll ask Nick time she comes on. She knows more about >> I'll I'll agree long-term it's better to >> Well, I'll I'll rely on whatever Clare Collins says.

[00:07:38]>> Thanks, Mark. We've got Beans in Wollongong here, Dr. Beans. What's your question?

[00:07:43]>> Hello, doctors. Um so, my question is around infrared cameras. Um so, they used a lot for like facial ID on phones and stuff like that. And also recently, I got some custom orthotics and they used uh the infrared camera off an iPad to like make the mold of my foot.

[00:08:02]>> Really?

[00:08:03]>> I was wondering how infrared works. Is it sending a signal and something bouncing back? Is it just a sensor detecting something? How does it get a 3D image? And if it's sending that signal, is that in any way harmful?

[00:08:18]Like, how does that all work?

[00:08:20]>> well, it certainly won't be harmful. It won't be any more harmful than getting radiation from the sun. Yeah, we should see. So, the sun puts out about half of its energy that it sends to the earth.

[00:08:31]Half of its energy as visible light.

[00:08:33]Mhm. Uh that's 400 to 700 nm in wavelength. And then uh the other half of the energy, slightly more than half actually, is from 700 up to 30,000. And you We humans do not have specialized receptors for that. We just feel it on our skin. The sidewinder snake can pick up things at night by the heat that they deliver, but we don't have that ability. So, in general, um it's not harmful to have some degree of heat landing on you. And um there are some infrared cameras that are used in the dark for the military where they actually send out an infrared beam and then just pick up the heat coming back. So, it's just like sending out light except your eyes won't detect it. So, you, the enemy, are not aware that you're being scanned. And if they're sending out heat, it's not harmful unless you know, it causes burns. Is that what you're worried about? And then tell me about what they did for your orthotics. I don't understand that well. That's new to me.

[00:09:28]>> Yeah, so um basically, I had my knee up on the chair so they could see the bottom of my foot.

[00:09:35]Um and they used So, an a tablet iPad that has an infrared camera on the front to scan the bottom of my foot, which then created a 3D image on the screen, which then got sent away to a company to make the custom orthotics to exactly the shape of the bottom of my feet.

[00:09:55]>> Wow. Okay, so first thing is that all [clears throat] the cameras on the phones pick up infrared. It just turns out that the technology that we use picks up infrared and visible. And you can prove this by getting a remote control for a TV.

[00:10:10]One that puts out an infrared beam. And then aim it at the camera on your phone.

[00:10:16]>> Mhm.

[00:10:16]>> And then press the button.

[00:10:18]And your eyes will not see a single thing. But the sensor on your camera will pick up the infrared, and you'll suddenly see the front of your remote control for your TV putting out a little blip of light.

[00:10:31]>> Wow.

[00:10:31]>> So, most cameras can pick up infrared. So, um, I don't think it's harmful, and and good on you for getting the orthotics. If you had a bit of what, plantar fasciitis or something like that?

[00:10:41]>> Uh, no, I was born with a a clubfoot.

[00:10:44]And, um, yeah, just finally getting it addressed.

[00:10:48]>> Oh, oh, that's such a good outcome. Hurray for modern technology helping you.

[00:10:52]>> Yeah, for sure. For sure.

[00:10:54]>> Great. Thanks, Beans.

[00:10:55]>> Thanks a lot, Beans.

[00:10:55]>> Thank you.

[00:10:57]>> [music] >> Jacinta in Mackay, you are pregnant.

[00:11:01]You've been noticing something. What's going on?

[00:11:04]>> Uh, morning, doctors. Uh, big big fan, long-term fan.

[00:11:07]>> Hey.

[00:11:08]>> Welcome, Jacinta, and congratulations.

[00:11:10]Is baby number one?

[00:11:12]>> This is baby number two.

[00:11:13]>> Okay.

[00:11:13]>> you.

[00:11:15]Um, my question is >> Yeah.

[00:11:16]>> Um, I had something spicy to eat the other day, and not long after the unborn baby was started hiccuping, cuz I could tell cuz it was quite rhythmic. And, um, I timed it. And each hiccup was less than a second. I couldn't give you the exact cuz it was quite quick. And I was like, "Why are hiccups rhythmic?"

[00:11:38]>> Wow. And how many weeks are you in on your second pregnancy?

[00:11:42]>> 28 weeks.

[00:11:43]>> Ah, so you've been feeling the baby from probably 16 or 20 weeks?

[00:11:47]>> Yeah, correct.

[00:11:48]>> But this is the first time you felt the hiccuping?

[00:11:50]>> Yeah, well, I may have felt it with the first one, but I can't remember. But I got more interested this time in the timing of it all.

[00:11:56]>> Okay, it's for muscle building. So, um right now the baby's floating around inside my favorite organ, the uterus, drinking amniotic fluid, which is basically its own wee.

[00:12:07]And so, its lungs are full of this liquid.

[00:12:11]And when it gets born, when baby gets born, they're going to have to start breathing air.

[00:12:17]And breathing air is a whole lot different from the slow rhythmic movements that it does with bringing the liquids in and out of its lungs. And it's got to be able to breathe air perfectly from when it gets born, and then it has to keep on doing it for the rest of his life. Very, very, very rarely, a baby can't do this. And a whole lot of bad things happen, but we can work around it.

[00:12:39]But the training begins at 11 weeks. And the training is hiccuping. For about a few hours a day, the baby hiccups consistently training itself. It turns out that the hiccuping is training its muscles so it can breathe when it's born.

[00:12:54]And so, it turns out that what they've done is a rhythmic training. Now, I haven't gone into it deeply enough. I'd be willing to bet that over the period of from 11 weeks on, there'll be sometimes when it's hiccuping faster and slower, and maybe trying different types of hiccups. Um and as a result of this hiccuping reflex being absolutely essential for the baby to survive, it's a very strong reflex, and in adult life, hiccuping has no function except to be really annoying.

[00:13:24]And so, some people are stuck with hiccuping because it's such a strong reflex and I think the world record was 58 years in the USA which was cured by and I quote about b o u t of fierce praying. I don't know what fierce praying is but it seemed to work on this person. So, enjoy the fact that your baby will be ready for breathing air when it gets born.

[00:13:45]>> Oh, awesome. Thank you so much.

[00:13:47]>> Very good. And if you can't actually time it and pick different rhythms along the way, well, that might mean you have to eat spicy food to make it more >> Yeah.

[00:13:54]>> You don't want to do that.

[00:13:55]>> that >> um >> Bring on the hiccups again.

[00:13:57]>> Bring on the hiccups. Yeah.

[00:13:58]>> I don't know.

[00:13:59]>> That'll be my next experiment.

[00:14:00]>> Yes.

[00:14:01]Good luck to Jacinta.

[00:14:02]>> Thank you, Dr. Jacinta. I look forward to your lovely baby in 18 weeks or whatever it is.

[00:14:06]>> Yeah. 16.

[00:14:07]>> Mark in Melbourne, you've got a question about our muscles. What's going on?

[00:14:11]>> I do. Hi, Dr. Lucy and Dr. Karl.

[00:14:13]>> Welcome.

[00:14:14]>> Um Thank you. What I'm particularly interested in is the process that I guess makes us stronger. So, for example, I used to have a reasonably sedentary career. Last 10 years, it's quite physical. And I do know that I am stronger for the work I do. And I know that applies to athletes and you know, people go to the gym and things like that. So, I just want to understand what the process is that actually tells us to get stronger or tells our muscles or >> Right. And just before we start, what was the physical activity lifestyle change that you went into? Did you become a laborer or gardener?

[00:14:49]>> Correct. Laborer, gardener, and maintenance. So, it's all physical.

[00:14:53]>> Gardening can really challenge you. So, where have you noticed the muscles on your upper body, lower body, abdo?

[00:15:00]>> Actually, it's pretty evenly. So, I know I have I definitely my legs are stronger from from I you know, do a lot of climbing, a lot of walking, but also upper body, too. So, yes.

[00:15:09]>> Oh my god. Lucy, you and I could open a gym of pseudo gardening where people come in and we hire them out as gardeners.

[00:15:15]>> Yes. [laughter] >> And we charge them to be gardeners and we make money from the people. Okay, let's not go down that pathway. So, firstly, there's fast twitch and slow twitch muscles for fast explosive activity like um running 100 m or for more sustained work by lifting and putting down lifting down. They're called fast twitch and slow twitch or type 1 and type 2 muscle fibers. The reason your muscles are getting stronger is cuz they're getting physically bigger and they're getting physically bigger because you're damaging the muscles by the use that you're doing each day and the repair mechanism is not a bad repair mechanism. It's a good repair mechanism.

[00:15:55]So, think about like linking your two fingers. How would you describe this activity here linking your fingers of the palms of your hands and you sort of form a a ratchet mechanism and you walk one hand up the other hand and so that's called actin-myosin.

[00:16:09]They you got two of these two molecules that ratchet against each other. There's some really great videos on TikTok about that actin and myosin.

[00:16:16]And what happens is that they are the parts of the muscle fibers that actually do the pulling and when you do regular work you damage the muscles that you have but it's not as though oh no, don't do regular work cuz you'll damage them.

[00:16:28]It's a a good damage as opposed to a bad damage. I'm not talking about overworking it and tearing a ligament or something like that but just doing a graduated repair. You tear the microfibrils and then stem cells kick in and they add extra microfibrils. You are adding extra muscle fibers that were not there before and they come from stem cells. And so if you do this regularly over a graduated period, you get stronger.

[00:16:53]If you do absolutely nothing and just lie in bed all day, you will lose 30% of your muscle strength at the end of a 24-hour day of lying in bed not even getting out of bed to wee or eat or anything and it goes like that and as a result of the astronauts in orbit, even though they spend 2 hours a day doing exercise if they've been up there for say 9 months, maybe you got to take them out on a wheelbarrow. They can't even stand up in those gravity even though they exercise for 2 hours. So, the original muscles are getting bigger because of these microscopic tears that make the stem cells make new fibers.

[00:17:26]And look up TikTok for the or look up for the videos of actin and myosin there's some great videos on that.

[00:17:32]>> Okay. Can I just ask a related question?

[00:17:34]Do things like creatine and all that help in that tear repair?

[00:17:40]>> Uh they don't help, but they act as a substitute for ATP. ATP stands for adenosine triphosphate. It is your energy molecule.

[00:17:51]It is a equivalent to a dollar bill. Do we We don't have dollar bills anymore.

[00:17:55]We got dollar coins. Five dollar notes, right. If you want anything to happen in our society in general, you have to spend money. I'm not talking about kindness, but you have to spend money.

[00:18:03]And if you want anything to happen in your body, you have to burn up ATP. At any given moment, you've got about 2 or 300 g of ATP.

[00:18:13]But in the course of a day, you'll make your own body weight.

[00:18:15]And when you're pumping iron or working extra hard, you kind of run out of ATP in a little way, and then the creatine can kick in.

[00:18:24]So, it can act as a substitute for ATP. And so, you can push yourself a bit further, and as a result of that, come out of the you know, after a few months, come out with slightly bigger muscles than if you hadn't. So, what it does is it lets you push yourself a little bit harder, but of course you don't want to go into damage. You can go into serious damage, don't do that.

[00:18:44]>> Right. Okay.

[00:18:45]>> Great. Does that help, Mark?

[00:18:46]>> Oh, and by the way, uh absolutely. And Wendy Zukerman has a wonderful podcast on that on Science Vs. where she interviews a professor of exercise physiology who was also a bodybuilder.

[00:18:56]>> Oh.

[00:18:57]>> And so, he he he's got a personal interest in looking gorgeous. And he's from somewhere in Texas, I don't know where.

[00:19:02]>> [laughter] >> Maybe love.

[00:19:03]>> A personal interest in looking gorgeous.

[00:19:05]Hey John, you're also in Melbourne.

[00:19:07]What's your question about meteorites?

[00:19:10]>> Hey Dr. Karl. So, my 7-year-old Raymond, uh he asked me a ripping question on space junk junk landing on Earth. So, how does space junk or meteors burn up as they come towards Earth? Is it them having to go through kilometers of um hydrogen and helium atoms and them chipping away, or is it something else that burns them up?

[00:19:31]>> It's the same effect as pumping up a bicycle tire. Have you ever done that?

[00:19:36]>> Uh no.

[00:19:37]>> Okay, so if you have friends who have a bicycle, ask them if as they hold the bicycle pump in their hand and one hand and then do the pumping, does the bicycle pump get hot? And the answer is yes. If you compress air, it gets hot.

[00:19:52]And if you come into the atmosphere at several kilometers a second, you are compressing the air to a military industrial grade. It gets very hot, hot enough to melt aluminum. And what we've been finding is that with the satellites that we've been putting in orbit, there are so many returning that we are now contaminating the stratosphere with aluminum. They use aluminum spacecraft where it's not heat-critical because it's so light and relatively strong.

[00:20:22]And we've recently found that 10% of all of the droplets of fluid that we found in the stratosphere are contaminated with aluminum from returning spacecraft. And this is going to increase enormously as the number of working satellites in orbit increases.

[00:20:37]It was a few thousand in 2018 2019, currently about 14,000, by the year 2030, which is only 4 years away, to 50,000. And they'll be returning at the rate of 10,000 a year or several every day. And so, we'll be ending up with you seeing lots of these things coming back to Earth and unfortunately contaminating the upper atmosphere, which is something we should think about now because we don't want to damage our planet too much. So, the short answer to your son is the pressure mo- from pressure creates heat. The air molecules bang into each other and it can get hot enough to melt aluminum and even iron.

[00:21:13]>> Got you.

[00:21:15]>> Can you relay all that, John?

[00:21:17]>> Will do. Will pass that on to my 7-year-old tonight.

[00:21:20]>> Oh, yeah. Tell Raymond we said hi. Yeah, listen to the podcast. That's it.

[00:21:24]>> what what's your son's name? Raymond?

[00:21:25]>> Raymond.

[00:21:26]>> Raymond.

[00:21:26]>> Raymond, yes, this is for you. Um we hope you enjoy it from Lucy and me. We love you, Raymond.

[00:21:32]>> [laughter] >> Thank you, doctor.

[00:21:34]>> Hi, Raymond.

[00:21:37]>> And Raymond's dad, John.

[00:21:38]>> See, this is the thing. You get on, we could give you a direct message to you or someone you love, okay?

[00:21:44]>> [music] >> Now, Dr. Karl, we had a question about the rhythm of hiccups. Nate has texted in saying my missus gets hiccups whenever I make her laugh. It's my barometer for a good joke.

[00:21:54]>> Oh.

[00:21:55]>> That's nice.

[00:21:56]>> And he's keeping the family happy.

[00:21:57]>> Exactly. And we also had a question earlier about um infrared technology, particularly particularly in the making of orthotics.

[00:22:05]So we've got Matt in the engine, Brisbane. Now, Matt, you have a bit more insight for us. What can you tell us about this technology?

[00:22:13]>> Good day, doctors.

[00:22:14]>> Dr. Matt, welcome. [laughter] Thank you for dialing in cuz I'm only a generalist and I love talking to specialists like your own good self.

[00:22:20]>> I'm not really a specialist, just a massive nerd with an interest in 3D technology.

[00:22:24]>> And you know more about than I do. Lay it on us, man.

[00:22:26]>> So what actually happens is a with your phones and tablets and 3D scanners, they use a what what what I believe the professionals would call a IR constellation. So an infrared constellation. So each of those it essentially throws out a bunch of lines of IR light.

[00:22:47]And each of those lines is known by the computer where it is, where it is in space, how and what angle is in between those two lines.

[00:22:57]>> Ah, so if it's putting these lines onto a flat surface, it'll get parallel lines back, but if it's putting it onto a wavy surface, they'll be curves.

[00:23:07]>> Exactly. So, you're able to find out very very accurately um how far away the surface is, uh what plane it's on, uh how it's moving, um a lot of different information uh using these IR constellations.

[00:23:26]Um a lot So, with your phones and tablets, they'll use maybe one constellation and maybe one or two cameras to find out how far away it is and what it looks like. With the big 3D scanners, they'll use three, four, five cameras and about six different constellations. And they'll be scanning in lines or circles or however they decide is the best way to do it.

[00:23:53]>> Ah, so then that way with um who was it who's getting the matter Was it just Sinta?

[00:23:58]>> Mhm.

[00:23:58]>> I think I can't remember, but um that means that they can then shape the orthotic precisely she had the club foot to the shape of the bottom of her foot.

[00:24:09]>> Beans.

[00:24:09]>> Beans, Beans. I was wondering about that name. I love Beans.

[00:24:11]>> Yeah, Dr. Beans.

[00:24:12]>> Good name. And so, they can shape it precisely Oh, what a good use of technology.

[00:24:17]>> Right down to the millimeter.

[00:24:18]>> Oh, yeah.

[00:24:19]>> Probably probably sub-millimeter precision.

[00:24:21]>> Oh, yeah.

[00:24:23]Wow.

[00:24:24]Oh.

[00:24:25]>> Well, Matt, thank you so much for following up.

[00:24:27]>> Thank you, Dr. Beans.

[00:24:27]>> Absolutely. No problem. Have a awesome day.

[00:24:30]>> You too. We love it. We love your comments. We love your stories.

[00:24:33]0439757555.

[00:24:36]Erin in Wollongong, you are studying for an exam. When's the exam?

[00:24:40]>> Um hi, doctor, by the way. Um my exam is in 2 weeks, and it's um on first-year psychology. So, I'm doing a bit of biology in there as well.

[00:24:52]Um and I was just calling to ask if you know how an action potential is fired in a neuron or anything like that.

[00:25:01]>> Ah. So, you imagine you've got a nerve and it's a hollow tube and the biggest and so the longest and fattest nerve in your body is a sciatic nerve running down to the tips of your toes from the base of your spine.

[00:25:16]So, imagine you've got this pipe. Say we'll call it like a It's a plastic pipe and and there's all sorts of complicated stuff inside. Uh we're discovering micro tubes and all sorts of stuff. But the wall by selectively allowing sodium to get out and potassium to come in, it maintains an electrical potential.

[00:25:37]So, there's 80 mV negative, 80,000 mV on each of the cells in your body, uh especially nerve cells.

[00:25:44]The ones that are different are the ones in your ears. They've got 140 mV because that's a special trick to make your ears more sensitive. But getting back to the general, you've got this potential difference, this voltage, across the cell wall of your nerve.

[00:25:58]And for whatever reason, it breaks down suddenly. Suddenly, all the pumps switch off. So, you've got these things called sodium potassium pumps.

[00:26:08]When I went through medical school, there was only one. Now there's about 19. And an um mutation in one of them leads to you not feeling any pain. Look up the Pakistan circus athletes. But that's a different story. So, normally that potential is maintained by pumps which are powered by ATP.

[00:26:28]They stop.

[00:26:29]And then suddenly things start equalizing and you get a temporary depolarization.

[00:26:33]And then that depolarization runs in a particular direction away from the nerve body. I suddenly realized I don't know why it runs away from the nerve body.

[00:26:41]Maybe it goes in both directions, I don't know. But it runs away and the bigger the nerve, the faster it travels.

[00:26:48]And the smaller the nerve, the slower it travels. So, something like smell would be fairly small. Pain would be fairly big cuz you want to know about pain fairly quickly. And this depolarization potential then runs to the end of a nerve, and you've got a sort of a rounded end, a sort of a male-female thing, like two soup bowls in each other, and it causes depolarization at the end of the nerve.

[00:27:10]And there's a thing called the synapse, the gap's about 20 billionths of a meter across, and suddenly these tiny vesicles of chemicals little balls of chemicals merge with the cell wall and go into the gap. And they could be adrenaline is it could be one, and they travel that very small distance very quickly, and when they land on receptors on the next nerve, they set off another depolarization.

[00:27:36]So, it goes electricity, chemicals, electricity, chemicals as it travels from one nerve to the next through your body, and then you can end up doing something like I want to move my finger, and your finger moves.

[00:27:47]Now, I'm guessing does is that helpful a bit? And can I suggest Wikipedia as well?

[00:27:53]>> Yeah, that was really helpful. Like I had a general idea, but I think that really narrowed it down. Um, especially with like the sodium and potassium kind of ideas as well. So, thank you so much.

[00:28:05]>> sodium potassium pumps work on a three-to-two ratio of three atoms of one to two atoms of the other, and you normally have a high blood sodium, so inside the cells is very low, and you have a low blood potassium, so inside the cells is high. And so, these pumps are always running. So, start learning about these pumps, and once you understand the pumps maintain the electrical balance, then you're on a good start. And and best of luck with your exam, Dr. Aaron.

[00:28:32]>> Yeah, good luck for your exam, Aaron.

[00:28:33]>> Break a leg, as they say.

[00:28:34]>> Yay! Text us in a couple weeks and let us know how it goes.

[00:28:38]>> Sure.

[00:28:39]>> Love you, kid. We've got Ellie in Tiak here. Ellie, what's your question?

[00:28:44]>> Hi, doctors. Um, I my partner and I own a little bit of land and we have noticed that we will walk past a certain spot, you know, a hundred times and see absolutely nothing in the ground, but then you walk past one day and there'll be just like a random like bit of hose or like a tap sticking out of the ground that you've never seen before. We're just wondering where it is like how does that get to the surface and like the Is it erosion or but these things could be really really old. And they [clears throat] just turn up and you're just like, "How did How did you get up there?" even when it hasn't rained or anything like that.

[00:29:21]>> But you do have ground movement all the time. So, the classic case relates way back to Henry Thoreau who about a century and a half ago in the top right-hand corner of the USA decided he would go and think his way into clarity and went to a place called Walden Pond and built a house and then he's realized that there were rocks that would heave themselves out of the ground.

[00:29:45]>> Mhm.

[00:29:45]>> And that was due to freeze-thaw cycles and they force themselves into rings and he wrote a poem called Building Wall. I think my memory's right on that. Maybe somebody else wrote it, but it's called Building Walls and it's related to these things heaving themselves out of the ground and you're dead right. So, if you've got big temperature changes and especially ice being formed and melted, you'll get stuff heaving out of the ground.

[00:30:08]Otherwise, you're relying on movement in the ground. The ground is not dead solid. You want dead solid, you put in it some rock or some concrete. But if the ground will move anyway and so you can have rain and you can have just um temperature cycles as well slowly heaving stuff out. But you're saying you find even a tap coming out of the ground? Can you tell me about that?

[00:30:29]>> Oh, like taps and like tap handles and just like old rubbish that's obviously been in the ground for a long time and then all of a sudden it's there and sticking out of the ground.

[00:30:40]>> dump or waste heap?

[00:30:41]>> Yeah.

[00:30:42]Oh, there was a hoarder that lived there. Yeah.

[00:30:44]>> Wow.

[00:30:45]>> [laughter] >> You do find a >> There's treasures everywhere.

[00:30:48]>> Yeah. So, it's basically the wind and the water and the temperature change.

[00:30:53]And as I said, it happens faster the bigger the temperature change.

[00:30:57]>> Yeah, right. There you go.

[00:30:59]>> And it's it's really weird. So, we had our little um grandson over from New York and it was the first time, he was 2 years old, he ever played in dirt.

[00:31:09]Cuz you can't play in dirt in New York cuz you'll find all sorts of bad things.

[00:31:12]>> Yeah, that's true.

[00:31:13]>> The first time in his life he walked on sand. He loved [laughter] it. He loved it. He loved it. And so, there's all these photos of them running around all new.

[00:31:21]Oh, sand. I'll roll in the sand. I'll roll again.

[00:31:23]>> It's so nice. Clean sand.

[00:31:25]>> So, yeah, that you just see the debris of the past.

[00:31:28]>> Ellie, thanks for your question.

[00:31:30]>> No, thanks, doctors.

[00:31:31]>> [music] >> Right now, we're going to go to Newcastle with Nate. Now, Nate, something pretty traumatic happened to you a couple of years ago. Do you mind talking to us about it?

[00:31:41]>> Not a problem. Thank you for having me.

[00:31:42]Good morning, doctors.

[00:31:44]>> Good morning, Dr. Nate. Welcome.

[00:31:46]>> Uh so, yeah, about a year and a half ago, um I was unfortunately coward punched in the side of the of my right right side of my head.

[00:31:55]Um and ever since I've had um basically shots of pain uh that shoot through my head and go all the way down the side of my body.

[00:32:05]Um not a migraine. I've had a migraine.

[00:32:07]I felt that I know what that's like.

[00:32:08]This is something different. I have had an uh an MRI scan as well and got the all clear. So, I guess I'm just kind of putting it out there. What could I possibly dealing with? Like, is there any other information I could maybe get?

[00:32:22]>> Uh have you been dealing with a pain clinic or neurologist?

[00:32:27]>> Not as of yet, no. That's kind of been my next thing is maybe I should go to a neurologist, but >> Okay. Look, I'll give you the good news first. So, um the good news is that you can recover from whatever damage was caused. So, some damage was caused um and you can recover from it. So, the first example is way back when CAT scanners were first invented.

[00:32:52]And they were trying to work out how to make this complicated technology work and they were just testing it on each other. And there was a guy there who was a physics honors graduate. Um he had an IQ of 123 and he said, "I have my turn to scan me." Now, in your brain, in your head, you've got firstly, this hard skull, then some skinny membranes, and then the brain meat, the flesh of the brain, and then a hollow chamber in the middle with liquid. And the brain meat is, I don't know, 50-60 mm thick.

[00:33:22]He had 1 mm.

[00:33:24]Not 60 mm, right? And it doesn't show that you don't need your brain. It says that you can recover from trauma or defects and still have a normal life.

[00:33:36]Okay, so that's the first message of good hope. Um and the second one is that if you people who have suddenly acquired blindness for whatever reason in life and learn braille, they're not using their visual cortex anymore and they retrain their visual cortex, two areas the size of a ping pong ball at the back of your head, to do the braille. You and I do braille, we do it um at the front part of our brain. They do it in the visual cortex at the back. So, you can retrain your brain. So, so they've had an injury and the good news is you recover from. With pain, it's really worthwhile going to a pain clinic.

[00:34:13]Um a little diversion here. With back pain, often you have an injury, the injury heals, but your brain has learned to have the pain, and so even though there's the injury is gone, you still have the pain, and pain clinics can help you get out of that. And also a neurologist, so you need to go through your GP, and there are the two pathways to head down. Pain management and a neurologist, and almost certainly you can have a better outcome further down the line.

[00:34:37]>> Wonderful. Thank you so much for that. I do appreciate it.

[00:34:40]>> Yeah, thanks for sharing, Nate. Hope you get well good.

[00:34:42]>> I really hope you get better. I I I'm confident that something better will come out of it.

[00:34:46]>> I'll push through. Won't keep me down.

[00:34:48]>> Oh, thanks, Nate. We got Bex in Yarra Lake now. Bex, this is something Dr. Karl and I deal with all the time.

[00:34:55]What's your question?

[00:34:56]>> So, I was just wondering why I sometimes mix up my words. Um it'll happen randomly with random words, but then it always happens with orange and green. Like I'm thinking orange, I think I've said orange even in hindsight, but green comes out of my mouth.

[00:35:12]>> [gasps] >> Wow.

[00:35:13]>> Bex, a great color combination as well, and a very flavorsome color combination.

[00:35:17]I won't say what product, but I love an orange and a green together. Yeah, why what is that, Dr. Karl? That kind of association maybe.

[00:35:26]>> Yeah, the the thing is that talking is the most complicated activity that a human can do, and if you get a child who apparently talks fairly well, an 8-year-old 8-or-9-year-old child, and say, "Can you say for me the words British Constitution?"

[00:35:41]Almost certainly [snorts] they'll slur, because they can't do it yet, but they will. Normally they get there by 10 or 12. So, I have a brain defect, which is that I will very confidently say the wrong word, and I can be reading off a script or an auto-cue, and if my producer here at the ABC is paying not paying attention, instead of saying "The environment has changed blah blah blah," and I will say very confidently, "The elephant has changed," and I I'll I'll put it totally confidently, and I don't I have no record of saying that.

[00:36:13]And it happens. So, trying to speak is really really complicated, and it's amazing that we can do it as well as we do, and that's a very poor explanation of why we make mistakes. It's admitting that we do, but why you juggle up different things is such a complicated activity cuz you got to use so many things in your airways and that's part of the reason that many people, 1 to 5% of the population, will poke their tongue out to disable their tongue uh when you're doing a complicated activity uh so they're not using up extra processor cycles from their brain if they're trying to, for example, like Shane Warne spin a ball from the past cuz he was brilliant at that or like a basketballer they'll poke their tongue out and immobilize it with their lips or tongue. And so your tongue is using up just so much energy and processor cycles.

[00:37:03]I know it's a weak explanation and it's not surprising you make mistakes. I don't have a better explanation than that.

[00:37:07]>> Becks, what if you were talking about orange in the context of a fruit bowl, would you ever mix it up there?

[00:37:14]>> I don't think so. I think it's just in color context. Like I'll Yeah, but it's always those two colors so I just thought it was super weird.

[00:37:22]>> Wow. Okay. I reckon a lot of people could relate to this one, Becks. Thank you so much for sending in your question. Sorry we couldn't come up with something more solid.

[00:37:30]>> No, we really need a linguist person to talk to us.

[00:37:33]>> All right, Becks. Thanks for your question.

[00:37:36]>> Thank you.

[00:37:37]>> And we're going to finish up here super quick. Oh, actually, sorry. William, do you want to ask a question? We'll see if we can do it super quick.

[00:37:43]>> Yes, Dr. William, come on down.

[00:37:46]>> Hello. I'm just wondering what do scientists believe the next evolutionary change in humans will be?

[00:37:50]>> Dr. Karl, can you answer that in 50 seconds?

[00:37:53]>> Um there was a case of uh two athletes who got married and they had a baby who had muscles at the age of three.

[00:38:01]>> Crazy.

[00:38:02]>> Muscles at three, will that pass on? We don't know. Secondly, evolution is fairly slow because you got to have it consistently happening over a large number of people and generations.

[00:38:10]Thirdly, the plague swept through Europe but did not sweep through Africa. And it turned out that some people became resistant to the plague and therefore accidentally resistant to AIDS because they both, the plague and AIDS, use the same receptor to get into the body. And so there are people in Scandinavia who are have evolved to be totally resistant to AIDS. And then thirdly, with regard to living at high altitudes like in Tibet or the Andes or in Africa, there are three separate mutations we humans have done. What the next one will be, we have no idea.

[00:38:45]>> Wow.

[00:38:45]>> There are a good way of saying I don't know.

[00:38:47]>> Yeah.

[00:38:47]>> We've seen mutations come.

[00:38:48]>> And in just the right amount of time.

[00:38:50]William, thanks for your question.

[00:38:52]>> Thank you, Dr. William. Sorry we had to do so fast.

[00:38:55]>> Got nothing to say?

[00:38:57]>> He's being shy.

[00:38:58]>> He's William, you there?

[00:39:00]>> Oh, yeah. Sorry.

[00:39:01]>> Where did you go? WHERE DID YOU GO?

[00:39:03]>> [laughter] >> AND ALSO, WE ALSO CHANGING the diseases we have. It used to be in the old days that if you had cystic fibrosis, you did not have children. But now they do and they can pass the gene on. So we're doing that change to our society as well, which will have good effects and bad effects as well.

[00:39:19]>> William, you looked into it. Does that help?

[00:39:21]>> Yep, that helped. Thank you.

[00:39:23]>> [laughter] >> Where did he go? I've got no idea. All right. Dr. Karl, we'll do this again next week.

[00:39:29]>> It's good.

[00:39:31]>> And that's it. Thank you so much for listening to this week's episode of Science with Dr. Karl. Remember, if you want to submit a question right now, you can do so via a link in the show notes.

[00:39:41]It's going to take you to a Google Doc where you can submit your name, where you're from, your question for Dr. Karl, and whether we can give you a call. P.S.

[00:39:48]We really want to call you about your question, so please include it so we can have you on a future episode. This one was produced by Josh Brennan. I'm Lucy Smith. We'll catch you next week.

[00:39:59]>> Dave Marchese here from the Triple J Hack team. Hey, if you love Dr. Karl's podcast like I do, you might enjoy the Hack podcast as well. Each day we bring you the news that matters to you. From the latest science on climate change to what's happening in politics and news around the world. The Hack podcast, it's your daily fix of the news you need to know. Get it wherever you're listening now.