When we think that we live this very moment, we are wrong. It turns out, our brain tricks us so we're always 15 seconds out of date. So basically we always live a little bit in the past. This way, your brain helps you stabilize your vision of the world around you. Your eyes receive a huge amount of visual information and they need a little time to process it. Let's find out how it works.
Here're 13 coolest body facts that'll help you realize how unique and special our bodies are. You'll find out why you produce more saliva when you go for a run. And how you can burn calories while thinking. Have you ever wondered why our distant relatives, the primates, are so much stronger than us? We're gonna explore these and more questions about human bodies...
00:00The cornea is the only part of your body with living cells that doesn't have blood vessels.
00:07It gets nutrients and oxygen directly from the tear fluid on the outside
00:11and the thick, watery substance you have between the cornea on the inside
00:15and also from the nerve fibers connected to the cornea.
00:20That's why contact lenses used to be a potential issue.
00:24The older ones were reducing oxygen supply
00:26since the cornea mostly gets oxygen from the outside.
00:30This problem was solved, or at least reduced, when silicone hydrogel lenses came to the market.
00:37Some other parts of your body with no blood vessels are your nails,
00:41hair, outer skin layers, and tooth enamel.
00:45Did you notice your sweat sometimes smells of onions after your workout?
00:50You have nothing to worry about.
00:51There are two types of sweat glands in your skin.
00:54The first kind of glands are located on certain areas of your body,
00:58like the groin region and the armpits.
01:02They produce a specific oily fluid, which is a response to certain emotional experiences.
01:08Another type of sweat gland is way more common.
01:11They're distributed all over your body
01:13and are responsible for the specific sweat you get after the workout.
01:17The sweat cools your body down as it evaporates from your skin.
01:21It's 99% water, so it's practically odorless.
01:26Well, at least when it first leaves the pores and comes to the surface of your skin.
01:31But there are many types of bacteria on the human skin,
01:34and they feed on the nutrients in that sweat, together with skin flakes.
01:38One of the byproducts of this is specific chemicals,
01:42and their smell can sometimes strongly remind you of onion.
01:46You may have noticed you produce more saliva when you go for a run,
01:50especially if it's a short jog in cold weather.
01:54But if you're running a marathon, and it's a nice warm day outside,
01:58you'll produce less saliva.
02:01It's your body trying to offset the drying effect,
02:04since you breathe through your mouth way more.
02:06But your body becomes more dehydrated over longer periods,
02:12which is why it's trying to conserve water by reducing saliva production.
02:17Every training you do, no matter how intensive it is,
02:20also makes you secrete more of a specific type of protein.
02:24It makes the saliva more viscous and sticky,
02:27which is why you may feel like your mouth is dry way more after your workout.
02:33Humans see the world 15 seconds out of date.
02:36Which means your brain constantly keeps you a little bit in the past.
02:41This way, it helps you stabilize your vision of the world around you.
02:45Your eyes receive a huge amount of visual information.
02:48Yep, literally millions of colors, shapes, and ever-changing motion, wherever you turn.
02:54It's not an easy task for your brain to process all that.
02:58The visual world alters all the time because of changes in viewpoint, light, and the rest of the outer factors.
03:06Your visual input changes because you need to blink.
03:10Plus, your head, eyes, and your entire body are always in some sort of motion.
03:15Your brain has to establish a mechanism that can create illusory stability.
03:21It automatically smooths your visual input.
03:24It doesn't analyze every little visual snapshot.
03:27It's like a time machine.
03:28You actually perceive an average of things you saw in the past 15 seconds at any given moment.
03:36The brain pulls together objects, so they appear more similar to each other.
03:40That's why it tricks you into believing you're in stable surroundings.
03:44If your brain kept you updated in real time, the world would feel like a very, very chaotic place.
03:50With constant changes in movement, light, and shadow.
03:53Your bones are really strong, but your teeth, which we also consider as part of the skeletal system, are even stronger.
04:07That's because of the enamel, the hard outer layer of your tooth.
04:11The enamel keeps the tissue and the delicate nerves inside your teeth safe.
04:17You're basically burning calories while you're thinking.
04:19When you rest and don't engage in any particular activity, except for the basics,
04:24which includes digesting, breathing, and keeping yourself warm,
04:29it's the stage where your brain uses up to 20-25% of the total energy of your body.
04:36That means your body will burn around 350-450 calories per day, while pretty much doing nothing.
04:43We're not the only ones in the animal kingdom with such a mechanism.
04:47Some small mammals, like the minuscule pygmy marmoset, and the tiny tree shrew,
04:53devote the same percentage of their total body energy to their brain.
04:58Most of the energy the brain burns is to help its cells, the neurons, to communicate with each other.
05:04They do it via chemical signals the brain transmits across synapses, those special cell structures.
05:10So, the brain directs a lot of energy towards synapses in order to make them work.
05:15Your brain never really rests.
05:19Even when you're sleeping, certain parts are active.
05:22So, your brain needs its fuel to work, and you're basically burning calories in your sleep.
05:28The more demanding mental tasks you take throughout the day, the more calories you burn.
05:33So, if you skip today's workout, solve some Sudoku!
05:37Do you like to rush with your ice cream?
05:41Sometimes it pays off, but if you do it often, you must know the feeling of brain freeze pretty well.
05:48It's a pretty intense and uncomfortable feeling that comes from the front or sides of your head,
05:54right after you drink or eat something cold, such as a slushy drink, ice cream, or an ice pop.
05:59Some people even go through a similar sensation whenever they're exposed to cold air.
06:06Scientists are still not sure exactly why this happens, but one of the theories is the cold substance stimulates a cluster of nerves located at the back of the palate.
06:15Another theory says the blood vessels in the roof of the mouth and sinuses quickly constrict because the temperature in your mouth drops before they dilate again.
06:26Brain freeze is not something dangerous that you should be seriously worried about.
06:31And no, hanging over the table, groaning, or clasping your head in your hands won't help much.
06:36Some people like to sleep a lot. Hey, guilty as charged.
06:42But some have a certain condition called familiar natural short sleepers, which means they're kind of immune to sleep deprivation.
06:51About 1% of our population has it.
06:54They can fall short on sleep and feel pretty good about it.
06:58They're fine with sleeping for 6 hours per night.
07:01This amount would wreck the majority of people after a couple of nights.
07:04The human eye normally has 3 cones.
07:09That means we can recognize approximately a million different shades in the green, red, and blue spectrums of colors.
07:16But there are some people with a rare condition, so-called tetrachromats, that have 4 cones in their eyes.
07:22This allows them to see ultraviolet shades, which means they can distinguish 100 million distinct colors.
07:30Did you know your skeleton is all wet?
07:33I mean, your entire body mostly consists of water, up to 60%.
07:37That fluid is not only in your organs, muscles, and skin.
07:42It's in your skeleton, too.
07:44Your bone mass is almost one-third water.
07:48There's this amazing hidden network a human body holds inside.
07:52Blood vessels are really small.
07:54But if you could line them all up, you'd get something huge.
07:57Your entire body boasts a network of 60,000 miles of blood vessels.
08:02One of the ways to keep your network healthy is by eating right.
08:07Have you ever wondered why our distant relatives, the primates, are so much stronger than us?
08:12In many ways, our bodies are very similar.
08:16Look at the chimp's muscle structure, for example.
08:19But our closest primate relatives are approximately 1.35 times stronger than us.
08:24The human body developed more slow-twitch muscle fibers compared to the rest of the primates.
08:31This type of muscle fiber is a less powerful one.
08:34But it lets us endure more than other primates.
08:37And do things like foraging and hunting.
08:40Activities that helped our distant ancestors to survive.
08:43That's also the reason why we can run a marathon.
08:46A monkey could never do it.
08:48But we'd still lose in a strength competition.
08:52Laughter is contagious.
08:54It's not just a metaphor.
08:57Researchers have found that strong emotions can make the brain activity of different people sink.
09:02Laughter is something science usually links with social creatures.
09:07People are almost 30 times more likely to laugh when in some social situations,
09:12hanging out with their friends or people they feel relaxed with.
09:14One of the theories says that you're probably going to join when you see your friend laughing
09:19because humans are empathetic beings.
09:23Your brain will release endorphins when you're laughing.
09:25These are special chemicals that make you feel safe and at ease.
09:29So we're not sure why exactly our laughter is contagious.
09:32But it feels really good, so...
09:35Join us on the Bright Side of Life and Laugh Away!
09:44Thank you so much for joining us on the Bright Side of Life and Laugh Away!
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