Recently, I made a video about
what the world looks like in the ultraviolet.
Some things look the same,
but generally it’s hazier.
Sometimes light and dark are flipped.
Skin looks blotchier,
and fake teeth stand out.
Whoa, smile for me.
– 我的天- 我牙齿黑吗
– Oh, my goodness!- Are my teeth black?
– Do you have fake teeth, baby?
– 戴了- 哪颗？
– Yes.- Which one?
But the idea for this video started a long time ago,
with a question I had which is
how does non-ionizing radiation, like ultraviolet light,
damage skin and lead to cancer?
I do like to tell people that if you wanna see
how good your skin could look,
look at your butt,
cause that’s an area that doesn’t get the sun
and even old people have perfect butts.
It’s how your skin would age without the sun.
When I thought about what UV light
must be doing to our cells and our DNA,
I imagined it would be getting in there
and breaking all these bonds, and that would be the problem.
But in fact, it’s kinda the opposite.
UV actually facilitates the formation of covalent bonds
in our DNA that shouldn’t be there.
It comes in and it kinda creates these unauthorized bonds
between the basis called pyrimidine dimers.
Instead of having them bonded across,
it bonds the one next to each other, if that makes sense.
– 哦- 嗯
– Oh.- Yeah.
So what happens is two thymines which are side by side
can actually get covalently bonded together.
And that creates a lesion on the DNA.
You can think of it like a little bump that makes the DNA
hard to read and work with.
That’s not enough itself to cause skin cancer.
If that were the case, we would just be covered in skin cancers.
Then the next step is that we have to repair it.
And in the repair, that’s when you form mutations
that could eventually lead to cancer through bunch of different pathways.
And there’s actually people who have specific genetic issues
that they can’t repair these issues.
And they are covered in skin cancer.
UV has other effects on the body,
like it suppresses the immune system.
So, as Hayley says, it’s a double whammy.
There’s also kind of a double whammy,
because UV not only induces these unauthorized bonds,
it actually tamps down our natural immune system.
So one of the best ways we fight cancers through our immune system –
we have constantly immune surveillance through our skin.
So not only a sun like creating these problems,
– it’s actually kinda… that’s reducing our ability to fix them. – Reducing our ability to fix them.
So, so unfair.
UV light also causes us to visibly age.
It’s called photoaging.
I should clear up a misconception here that I had which was
I thought glass blocks all ultraviolet light.
So I thought if you’re inside a car, for example,
you really don’t need to put on sunscreen,
because you’re not being exposed to UV light.
The car does not block UVA, it’s glass.
It does block most UVB.
But you’re still susceptible to
those sunspots, those wrinkles through the glass.
And a lot of my patients, if you look,
and you compare their hands,
左手往往皱纹更多 看起来更老 有更多雀斑
the left is more wrinkled, older, has more sunspots on it,
because they’re driving.
– So they stick their hand.- Sticking their hand out. They’re truckers.
Absolutely you can see it the worst.
And there’s a really famous picture of
someone whose left side of the face
is significantly more, we would call it, like photoaged, old looking
than the other side of their face.
So that’s mostly UVA.
And UVA, as they set to longer wavelength,
penetrates a little bit deeper.
So wrinkles mostly come from destruction of our collagen and elastin,
which is natural fibers that hold up the scaffolding of our skin.
随着年龄的增长 那些分泌胶原质的细胞 即纤维原细胞
So with age, the cells that secrete collagen, they’re called fibroblasts,
they stop producing as much.
And what the sun does is it breaks down
the existing collagen and elastin we have.
So fibroblasts really like to be stretched, they like to be pulled.
And collagen does that collagen matrix.
So the sun damages the collagen fibers,
leading to less stretch on fibroblasts
and less production of collagen,
which means that we look a little more saggy.
I know it’s very depressing.
So sun protection helps…
the degradation of those collagen and elastin fibers.
You know, there are a lot of creams on the market
that claim to be anti-aging,
but the one that really works is sunscreen.
Preventing ultraviolet light from hitting your skin
is the best thing you can do to avoid skin cancer
and to avoid photoaging.
So yeah, it’s good advice. Use sunscreen.
Hey, I’m on set for Jurassic World: Fallen Kingdom.
And I’m here filming Sci-Fi Test Lab,
where we try to recreate some dinosaur parts
out of machinery and test them out.
So if you wanna see that, then click here.