Sunburn, Sweat and the Science of Summer!

Sunburn, Sweat and the Science of Summer!


[MUSIC] Hey everybody! It is deep in the heart of
summer deep in the heart of Texas here. As much as I’d love to be inside watching
YouTube videos with all of you, I had to get outside and enjoy this day. Now that we’re
out here, why don’t we check out some summer science. We can start with all this sweat. Sweat glands come in primarily two forms:
eccrine and apocrine. Apocrine glands are mainly found in places like armpits, and places
that contribute to body odor. Eccrine glands are distributed throughout your whole body,
and those are the ones that most of the cooling, and the shirt soaking. You’ve got between 1.5 and 4 million eccrine
sweat glands distributed throughout your skin. When your body’s thermostat, in the hypothalamus
region of your brain, detects a rise in body temperature or emotional changes or stress,
special nerve impulses turn on your dermal waterworks. Sweat glands work a lot like a well. Cells
at the bottom release little packets of water, salt and other molecules into the duct, and
it rises to the surface., where the cooling happens. Inside of a liquid, molecules are shaking
around, some a bit faster than others. Every so often one of them breaks free of the attractive
forces of its neighbors and flies off into the vapor phase. Over time, the molecules
that are left in the liquid phase are jittering less on average, and the liquid is cooler
than it was before That cools the blood near the surface, so
it flows back into your core and cools you off as a whole. And that might actually work
if you live somewhere less humid than here in Austin. Our bodies can make a max of 3
liters of sweat an hour, and I think I might be getting there. I need another way to cool off.
Now that I’m chilling out off in this 70 degree spring-fed water, something else cool
is happening. My fingers are getting all pruney. Scientists used to think that our fingers
and our skin were actually soaking up water, but it turns out, it’s an active process.
If we sever the nerves to the hand, then… no more pruney fingers. There must be a good
reason for it, right? Last year, neuroscientists tested people’s
grip: people with pruney fingers versus people with dry fingers, in wet conditions. It turns
out the people with pruney fingers had better grip, just like the treads of a tire on a
wet road. As you can tell I tan extensively, but I’ve
probably had enough sun for one day. A sunburn is most definitely an actual burn,
only instead of fire, it comes from radiation. Our atmosphere and ozone layer absorb different
wavelengths of UV light to varying degrees, but a good amount makes it down to Earth. When those UV rays hit your skin cells, they
can damage nucleic acids, either killing the cells, or engaging an immune system emergency
response… a lot like if you cut yourself. To repair the damage, cells release inflammatory
chemicals that make your skin painful to touch. And your skin turns red thanks to swollen
capillaries that are delivering white blood cells to the damaged area. Those damaged cells might die and peel away,
or they might respond by producing melanin, a natural sun protectant. But even with a
tan, and whether they come from the sun or a tanning bed, UV rays can fry your DNA into
these thymine dimers, which, when repaired by your cells, introduce genetic mutations
that can cause cancer. Ever wonder what those SPF numbers mean? Sun
Protection Factor measure how much of the UVB rays the chemicals in this sunscreen happen
to block. Unfortunately that scale tops out around 50, so don’t be fooled into paying
more for higher numbers. Unfortunately there’s no precise measure
of protection for UVA, the other UV component in sunlight. Bill McElligott drove a truck
for 28 years, and this incredible photo shows how those UVA rays, beaming through his driver’s
side window, can age skin. When you’re done watching YouTube for the
day, grab yourself a sweet treat, head outside, and try to find some summer science of your
own. Stay curious… and don’t forget your towel.

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About the Author: John Markowski

64 Comments

  1. I was wondering if people who live where the temperature is normally cold sweat easier/more when they visit a location with a higher temperature.Β 
    I know a family from Nigeria who moved to Ohio. They always dress their infant in sweaters and blankets even though it is summer. The mother said it was to get him used to the heat for when they go back to Africa. Is there any science behind that?Β 

  2. Here's a bit more in depth on the finger wrinkles by Alexis Dainis:
    Wrinkled Finger Rain Treads: Bite Sci-zed

  3. Dude.. that truck driver. Some of us are eating while watching! But informative as always πŸ™‚ As for wrinkled fingers, do any of our primate relatives have the same thing happen? Or is this unique to humans due to how our skin is?

    Also, random question.. What % of your total weight do you think you'd actually be if you took away the water weight and the weight of all your microbes?

  4. You should probably mention that when it's summertime for people up on the northern hemisphere, it's actually wintertime for people in the southern hemisphere.Β  I say this mostly because there still seems to be a lot of people don't understand that Earth experiences summer and winter at exactly the same time.

  5. The Heat of Sumner

    Very cool video, Joe! No pun intended. By the way, Barton Springs in good ol' Austin, Texas never looked sweeter! Thanks for the knowledge. The bit on "pruning fingers" is crazy good #science stuff!

    Thanks to @It's Okay To Be Smart for this original video!

  6. Science is awesome and everything, but the best part of the video is seeing a shirtless, wet Joe. πŸ˜‰

    But seriously, I had no idea UV-A was so prevalent. And the truck-driver photo was creepy. I used to wonder whether driving populations were more prone to getting skin cancer on the driver's side of the body (left side for countries like the USA, right side for countries like the UK). Probably too small to measure.

  7. When I see the host and others swimming in the spring or stream all I can think about is naegleria fowleri. I'm so freaked out by it that I do not even want to go near water especially in nature.

  8. I shouldn't have watched this video! It's 8 degrees today and almost snowing. Sucks to be in Australia right now!

  9. If you've ever found a severed hand in a creek before you know the nerves don't have to be intact for it to be pruney as hell.

  10. Three liters of sweat per hour!? Wow, I didn't even know I could drink that much water. The Boston Marathon had a one liter restriction. Unfortunately, Orwell didn't wake up.

  11. Ok, cool about why our fingers prune, but HOW?!?! How do we get those extra folds of skin on our fingers? We don't suddenly get a ton of extra skin cells, so what happens?

  12. Why do we find some video games satisfying and other a waste of time? Like graphics. But some people cant stand 1st person view but others cant stand 3rd person

  13. If brains and bodies are the same, why do we have so many different interests and a different way if thinking or processing information? And why some thought or interests are considered strange?

  14. Can animals sunburn? Is it because of their fur? If so, could we grow enough hair to never get sunburned?

  15. it would have been cool to get the different perspectives of different shades of skin, or different ethnicitiesΒ 

  16. Wow. That picture.Β 

    It makes sense, though. Both of my grandfathers were farmers, except one was a crop farmer, the other a cattle farmer. The cattle farmer spent more time inside working on milk processing and projects for the farm, and the crop farmer spent more time outside on the tractor, and his face looks very much like the photo you showed (the right half of the photo, that is). The other, the cattle farmer, had a very good complexion right until he passed away at 83 years old.Β 

    Oddly enough, my grandfather who was the crop farmer comes from a long line of crop farmers (both back in England and here in the states), and holy shit does skin cancer run rampant on that side of the family. πŸ™

  17. i have stayed out in the sun from sunrise to sunset doing stuff with my friends but never in my life did i got sunburnt yes i was black as a rock but it was never painful
    is it because iam from india?

  18. @Zubair Baraskar wow yeah that is indeed very likely, and its a hint about how adaptation works… if you think about it for a while… In hotter earth regions, there's darker skin people, in the coldest regions you see more whiter people, and its all thanks to the melanin protein, besides protecting the skin it also gives it that sexy brownish color to it.

  19. Somebody once said the SPF number was the number of extra hours you could safely spend in the sun per week by using that particular rating of sunscreen … it never sounded credible.

  20. I don't want to know how hot it can get in Texas in the summer. I live in Minnesota and I think our summers are hot enough! (but fun fact, I went to Florida one summer and when I came back to Minnesota, it honestly didn't feel that different) but urgh… I do know about humidity. I live in a suburb of Minneapolis, and it gets so humid it feels like it takes more effort to breathe.

  21. I was once trained how to be a lake/pool lifeguard buy a beach life guard that worked with the Red Cross. He was roughly 50, with good muscle mass for his age. But he had the skin of an 80 year old.. I guess all that time out on the beach did a dent to him

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