6ish of Your Everyday Actions, Explained | Compilations

the human body is a remarkable machine that can do all sorts of amazing things we can dive tens of meters into the ocean on a single breath or climb thousands of meters toward the sky to summit the tallest peaks but sometimes our bodies also do stuff that's pretty weird gross or just plain annoying over the years we here at scishow have talked about a lot of these other everyday things that our bodies do and apparently our patrons are big fans of these episodes when we asked them to pick a compilation topic they voted for us to smush a bunch of why do we episodes into one so here we go first you've probably laughed at some point today and if not well hopefully you will in the next 15 minutes or so at least we'll try to make it happen anyhow laughing is just one of those things all people do we laugh when were amused and when we're anxious but why what's the point of laughing let's let Hank explain you know it's like super funny laughter laughter is a physiological response that involves at least 15 facial muscles the respiratory system the brains limbic system and if the joke is really really good even your tear duct thought laughter doesn't always indicate happy times it can actually be a sign that something is seriously wrong with your brain gelastic seizures or uncontrollable and random laughter or crying can indicate the presence of brain tumors or other conditions like pseudobulbar affect a neurological condition that can affect stroke and brain trauma survivors and MS patients these conditions are sometimes called emotional incontinence because the sufferer can't control the outbursts which often have no root and now they're feeling and how we feel especially in groups seems to be what laughing is all about some laugh researchers and yes they are things known as gel atala gists think that much of our laughter is rooted in strengthening social bonds we're much more likely to laugh in a group than we are alone and we tend to laugh more easily around friends and family that shared experience brings us closer makes us feel part of the group we also laugh to express relief or to ease our nerves in stressful moments researchers theorize that there are a few specific reasons for laughing first there's the incongruity theory which maintains it's the element of surprise that triggers laughter whether it's an unexpected punchline or your friend tripping over a throw rug so like say you're watching people walk through a room all day your brain registers this as predictable and boring behavior then your friend walks in trips on a rug and drops a box of ping pong balls once you're sure that your friend hasn't safe falling on a bag of rusty knives you'll find the fall hilarious because it was sudden and unexpected and incongruous to the string of people you'd seen safely walking by and because ping pong balls babies and little kids go for this kind of laughter a lot they think really simple unexpected things like my my face is here it stared for five consecutive hours it's still funny here like using a banana as a telephone now if you're the one who tripped on the throw rug you're much more likely to laugh and surprised if you see your friend laughing with you this goes back to that shared laughter as social bond thing you're probably feeling pretty embarrassed intense but are also relieved that you aren't hurt that's where the relief theory comes in laughing is like a mental mini break your brain is constantly working taking in all sorts of information and/or around the body sometimes it just needs a happy surprise this is particularly handy in stressful moments the whole Hollywood wisecrack in the middle of a suspenseful scene phenomenon is predicated on this idea when Han Solo is in mortal danger he cracks a joke to lighten the mood he needs it chewy deeds it the audience at the edge of their seats need it humor helps us cope with stressful situations it sort of recharges our brains to face the task at hand scientists call this releasing cognitive energy the rest of us call it comic relief but now back to you tripping on that throw rug if everyone in the room is laughing at you and none of them are your friends they may be proving the superiority Theory of laughter it means that they're laughing at your misfortune and probably means that they're kind of a bunch of jerk faces superiority laughter still promotes bonding and in us-versus-them kind of way it doesn't show much goodwill though teenagers make fun of their parents and you know each other and pretty much everyone and so do lots of adults as well but our teen years are usually awkward and confusing and superiority laughter may help ease some of that pain so simply put we laugh hardest at what we know best and at what stresses us out the most and maybe that's why it's great for you both physically and emotionally it reduces the release of stress hormones that jac those fight-or-flight feelings it lowers blood pressure and oxygenates your blood flow it even increases your t-cell levels that help your immune response and B cells that produce antibodies also laughing a hundred times is estimated to burn as many calories as a 15-minute bike ride so you see laughter is not the best medicine but it's not a bad medicine either Wow there is a lot more to laughter than I thought but of course laughter isn't the only way we express emotions physiologically for example when we're embarrassed our cheeks turn bright red whether we want them to or not but other animals don't do this so why do we here's michael with some ideas in every culture and every ethnicity around the world people blush but animals don't and it's not just that most animals faces are covered in fur and feathers and stuff so we can't see them blushing they actually don't blush Charles Darwin called blushing the most peculiar and most human of all expressions which is awesome but why do we blush physiologically we understand it I mean we get the mechanics of why your face turns red when Burnie sneaks up behind you and pulls your pants down in front of the whole rest of the marching band Bernice anyway your face turns red because your sympathetic nervous system kicks in that's the network of nerves that controls your fight-or-flight response when it's triggered it signals the release of adrenaline and suddenly your heart rate picks up and you start breathing faster and then you're ready to run away your pupils dilate and blood rushes to your brain so you can take in as much information as possible and your blood vessels dilate in a process called vasodilation to improve oxygen flow it's basically the same effect you get from warming up before a workout but in the very hypothetical instance of my pants being pulled down the blood vessels in my face were responding specifically to a chemical transmitter called adenylyl cyclase it basically tells the blood vessels in your face to let the adrenaline in the weird thing is that these same superficial blood vessels in your face aren't usually affected by sympathetic responses I mean we don't blush when we're scared if we did that might be a sign that blushing served some sort of survival purpose but it only happens when we're not actually in danger so like why well some scientists believe that blushing evolved as a social survival trait when you blush then the person who's angry you can see that you're really sorry and the person who's laughing at you can see that you're visibly embarrassed if that sounds weird just think about the last time your dog chewed on the furniture then rolled onto its back when you got mad lots of animals have evolved this sort of behavior so they can say hey whoa I messed up I feel terrible and it's really hard to stay mad at your dog when it does that that's how you know it's working we may never know for sure why blushing became a thing but it could just be our way of saying sorry for chewing on the furniture huh I never thought of it that way but blushing is a social signal does make sense especially when you consider how often our bodies involuntarily do things that are considered offensive like we burp and fart a lot and while I get that we all have gas why do we have to expel so much of it all the time here is Hank to explain formerly referred to is belching in flatulence these two often lampooned bodily functions actually share a common cause swallowed air every time you swallow you take in some air but you can swallow even more air than normal if you eat or drink too quickly chew gum smoke drink carbonated beverages or even wear loose fitting dentures now the majority of swallowed air comes back up in the form of burps as the air builds up in the upper portion of the stomach it causes stretching that eventually triggers the lower esophageal sphincter to relax the result is air escaping up the esophagus into the mouth where the sound and smell of the burp depends on how much coke you just chugged babies in particular are big burp errs especially for their small size mostly because they tend to go up in too much air while nursing and because young digestive systems haven't developed to the point where babies can easily burp on their own it's up to mom and dad to Pat their backs help get those gas bubbles out but for babies and adults what about the air that isn't burped out well it passes from the stomach into the small intestine and later the large intestine along the way as it passes through the gastrointestinal tract that air mixes with the products of some good old back to your fermentation that's going on your guts and fermentation is the result of carbohydrates like sugars and starches that can't be digested by enzymes in the small intestine some foods that include these hard to digest starches include cabbage cauliflower beans and bran which explains why you may feel excessively gassy after that big bowl of chili when those undigested and carbs reach the colon and the lower intestines bacteria take over the by-product is a combination of gases that include carbon dioxide hydrogen methane even hydrogen sulfide a stinky one that mix of gases plus the air that you've swallowed is what makes its way through the large intestine to the anus where it is expelled of course everyone has different amounts of various species of bacteria and yeasts working away in their guts but I'm sure you're dying to know so I'll just tell you the average human toot contains roughly 59% nitrogen 21% hydrogen 9% co2 7% methane and 4% oxygen if that last 1% in the form of hydrogen sulfide and other sulfur compounds that is the most potent in terms of producing those notorious unpleasant rotten egg smells well some of these chemicals are produced by bacteria you're got eating sulfur-rich foods like eggs and onions and beans that doesn't help on the smelly front well now I know more than I ever needed to about the composition of firts thanks Hank while we're on the subject of expelling air though sneezing is another kind of annoying thing our bodies do and the reason might seem obvious but expelling pathogens from our noses is only a part of the answer to why we sneeze as Michael explains everyone everywhere occasionally sneezes it's something that humans and even some animals like cats and dogs and chickens just do but why why do we sneeze if your answer is that it's our noses way of getting rid of irritants and excess mucus you're right but only partly the scientists have long thought that sneezing technically known as stern mutation is a reflex when irritants like dust dander germs or pollen get into your nose your brain sends out a signal to get rid of it that same signal goes out if an excessive amount of mucus is hanging out in there to say if you have a cold this signal triggers a deep breath which you hold in your lungs for a moment and while you're holding your breath your chest muscles clench and pressure builds your tongue is forced to the roof of your mouth and you breathe out fast through your nose in the form of a sneeze that is the old short and still correct answer to the question why do we Sneed according to a paper published in 2012 in the journal fathom there's a little more to it than that and it all has to do with cilia the tiny hairlike paddles that line our noses and sinuses in the study a group of researchers from the university of pennsylvania basically grew a tiny nose they took cells from the nostrils of several healthy adults and grew them in an incubator for a few weeks until the cells had formed the same type of lining that's in your sinus complete with cilia then to mimic a sneeze the scientists puffed air onto the lining they noticed that the bursts of air triggered the celia to kick into high gear moving back and forth repeatedly for up to several minutes after the trick sneeze so why were they so active for so long any potential irritants would have been cleared out already well the triggered cilia were acting as a broom basically resetting the entire nasal environment not just the parts where there'd been irritating gunk just like computers do biologists think that our nose needs a reboot every once in a while and it's kind of furry restart button is made of all those cilia but it turns out that not everybody's sneezes actually reboot their nose in addition to looking at healthy people cells this same group of scientists took a peek at the cells of people suffering from sinusitis which causes inflamed sinuses and general nasal discomfort runny nose nasal congestion all that stuff they discovered that when they puffed air onto the tissue of the sinusitis sufferers the cilia didn't beat fast meaning that chronic sinusitis might have to do with cilia that can't properly reset post sneeze and that knowledge might help researchers develop treatments for it I hope my cilia stays healthy so my nose can stay clean with some occasional cellular sweeping though all this talk about your tents and nasal cells wriggling is making my nose itch and actually that's another odd thing our bodies do [ __ ] even when we just think about things here's Michael again to explain why that is hitching just thinking about it is making me kinda itch image can be caused by all kinds of things the usual culprits are things like bug bites poison ivy or strands of hair brushing against your skin but it's also brought on by skin conditions like eczema or psoriasis as well as seemingly unrelated things like brain tumors diabetes and chemotherapy with such a wide range of causes the itch seems to be kind of mysterious and it is but in the 2013 study published in the journal science two researchers from the National Institutes of Health discovered the physiology of how itching works which may eventually help chronic itches find relief scientists used to think that an itch was basically a low-level pain signal meaning that one kind of nerve cell detected both itching and pain but the study found that itching is actually linked to a set of special neurons that produce a neuropeptide called NPPB the scientists genetically engineered mice said that they wouldn't produce NPPB that exposed the mice to chemicals known to produce itching these mice could still feel their bodies heat pain and touch but they didn't scratch no NPPB no itch that's good news for people who want to stop itching because the more we understand about how itching works the closer we can get to be able to control it unfortunately it's not as simple as just blocking this neuropeptide because NPPB has another job too it's released by the heart to regulate the amount of sodium released by the kidneys which helps control blood pressure but for most people blocking itching wouldn't be a good idea anyway the itch gets a bad rap but it's a useful evolutionary development scratching an itchy spot could remove a pesky bug a dangerous plant or some kind of other irritant before they do damage to your body with all this talk of itching you might be starting to feel pretty itchy by now I know I am just thinking about itches can make you feel like spiders are crawling all over you researchers gave a lecture about itching to an unsuspecting crowd to study their response and the audience got to scratching with both a verbal and visual itch cues and it's not just us researchers have also studied the contagious effect of itching on monkeys and like a yawn being passed back and forth the monkeys watched another scratch and mirrored the behavior it might be annoying but there's also an evolutionary benefit to itching being contagious one member of your group is itchy that might mean they've been exposed to a parasite or there's some kind of irritant around which could mean that you've been exposed to so it's worth getting a head start on scratching just in case and now I'm feeling itchy all over and since he mentioned yawning I'm strangely tired too it's so weird that we yawn just because we hear or see someone else do it but why do we yawn in the first place here's Hank with some insights people are always wondering about why do people yawn and we do it every day especially when we're in a boring meeting or we didn't get enough sleep so it may not surprise you that we don't really understand all the reasons behind why we yawn and it's not just humans birds do it Jaguars do it even fetuses in the womb do it ah cetacean the act of yawning happens with almost all vertebrates the explanation you may be familiar with is that a great big gaping yawn is the brains way of ordering you to take a deep breath supposedly it gets rid of extra carbon dioxide and brings in more oxygen problem with that is that there is absolutely no truth that yawning really affects your oxygen levels instead recent studies show that yawning is your brains natural air conditioning system bringing cooler blood to chill out your overheated overtired grey matter your brain actually heats up as it uses some 40 % of your body's metabolic energy just like your laptop gets warm when it's been playing video games for hours body temperature also rises and falls as part of your circadian rhythm reaching its highest point just before we fall asleep which is why a series of yawns at 1:00 a.m. is your body's Way of telling you to stop going on reddit and just go to bed so just like your computer has a fan to cool things down a yawn does the same thing to your brain allowing you to continue processing information effectively how's that work well since you asked yawning has two parts first stretching your jaws when you yawn increases the rate of blood flow to your skull second the inhalation sends the gulp of air into your upper nasal and oral cavities which have mucus membranes covered with tons of blood vessels that project up into the forebrain this is the big part of the brain responsible for receiving and processing sensory information producing an understanding language in controlling motor functions many of the things involved in actually being you so the cool refreshing air entering your sinuses changes the temperature of the blood that's now hustling up to the brain making you more alert and helping you walk and talk and think more effectively don't believe us scientists study the brain temperatures of mice observing increased temperatures before yawning and measuring a dip in temperature afterward and a more simple experiment on humans ask volunteers to hold hot or cold packets to their heads to see if changing the temperature of their brain cases triggered yawning turns out that the hot-headed participants yawn 41% of the time all those who chilled out yawn only 9% of the time the next time you can't stop yawning as you're falling asleep in a sweltering class room in the middle of the afternoon remember that it's literally how your brain keeps its cool I guess my brain really needs to cool down right now because I I just can't seem to stop yawning so I'm gonna head out but before I go I want to say thank you to all of our patrons who voted for this compilation topic we hope you enjoyed the episode if you want to support what we do here at scishow and help us pick some future episode topics you can learn more about becoming one of our patrons at patreon.com slash scishow and if you can't stop yawning either well we have a whole episode on why yawning is so contagious you can find it over at our sister channel scishow site a channel which I might add was also picked by our patron community they're just so awesome [Music] you

Channel: SciShow

Views: 421,051

Rating: 4.8617282 out of 5

Keywords: SciShow, science, Hank, Green, education, learn, compilation, olivia gordon, why do we laugh, why do we blush, why do we burp, why do we fart, why do we sneeze, why do we itch, why do we yawn

Id: pxj0PRXaduI

Length: 18min 21sec (1101 seconds)

Published: Wed Oct 02 2019