Why Can’t Scars Tan or Grow Hair?


I have a huge scar on my spine and two on
my abdomen, but whenever I spend time in the Sun they turn bright red, and I’ve always
wondered why? Hello everyone, proud scar owner Amy with
you on DNews today! Scars are our body’s way of recovering from
trauma. Whenever body tissue is broken, it heals itself by producing more collagen to
fix the damage. For about three months, this process draws more blood to the area, which
is why scars start red, and eventually fade to pale. In the end, the new tissue heals
into a scar, and you’re left with a permanent reminder of whatever happened on that one
night in Vegas. But why do scars not look like the rest of
your skin? Our individual skin colour is determined by
a pigment called melanin. It’s made by specialized cells in our skin called melanocytes, in organelles
called melanosomes. The type and amount of melanin gives skin its individual colour:
more melanin, darker color, less, lighter. The amount of melanin is dependent on your
ethnicity, environment, and hormone levels. But, it can also change with exposure to the
UV radiation in sunlight. Tanning, which we’ve discussed before, is
the skin’s way of protecting itself against ultraviolet light. Certain skin cells produce
more melanin the longer you spend in the Sun. The darker pigment absorbs UV radiation so
it can’t penetrate the skin any further, which sounds great except that too much radiation
damages the skin causing what we know as a sun burn. The thing is… scar tissue doesn’t
do this! Scar tissue doesn’t have melanin, so doesn’t
have pigment! The reason why is actually a bit of a mystery to scientists. But one study
I found in the Indian Journal of Plastic Surgery suggests that the availability of melanocytes
to repigment scarred skin depends on the mechanism of the injury. Superficial injuries retain
the cells adjacent to the wounded area, but deep cuts destroy more elements, meaning the
only available source for melanocytes are the wound’s edges. So, deeper injuries take
longer to heal and end up with a lighter, melanin-free center compared to the surrounding
skin. And because they lack melanin, the cells that
form scars can’t produce more of it! So when a scar is exposed to sunlight, it just
can’t tan. And this doesn’t only make the scar stand out more, it also puts the
scar owner at an increased risk of UV-related skin damage! I’ve noticed this myself. My
scars turn red really fast if I don’t put sunscreen on them. Another odd thing about scars? They’re typically
hairless. And like a lack of pigment, this has to do with how damaged the skin is. Hair grows from the papilla, the living part
of the hair follicle inside the skin. When the skin is damaged deeply enough to disrupt
the follicle, the hair can’t grow. So, scars don’t tan and don’t grow hair, but
why are some more visible than others? Skin cells grow in specific directions in different
parts of your body. A cut made with the grain will heal into a much thinner scar than one
made against the grain. What all this boils down to is that scars,
for a lot of people, are unsightly and make them feel ugly, but they’re really evidence
of how incredible our bodies are at taking care of themselves. Speaking of scars, did you guys know Al Bean
got smacked in the head with a camera when Apollo 12 splashed down and ended up with
a nice little scar on his forehead? True story, and that’s not the weirdest space fact I
could throw at you! If you’re a sucker for old things in space come check out my channel,
Vintage Space, where I dig into all kinds of minutiae relating to America’s Moonshot! My scars came from surgeries after a car accident
when I was a kid, and I wear them proud! What about you guys? Tell us your scar-y stories
in the comments and make sure you subscribe so you never miss an episode of DNews.

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