Your Tattoo is INSIDE Your Immune System. Literally

Summary

When you get a tattoo, the needle violently pierces your skin, killing cells and letting in ink and bacteria. Your immune system rushes to the site, but can't break down the ink particles. So macrophages surround the particles, permanently trapping them in place to protect your body, which is why tattoos last. Over time, some ink escapes and spreads or fades. Laser removal also breaks particles apart, but new macrophages quickly take their place. Your lasting tattoo is a visible tribute to your immune system constantly working to protect you.

Takeaways

• 😲 Your skin is like a conveyor belt constantly shedding dead cells from the outside in
• 🩹 Tattoo ink particles get trapped inside immune cells called macrophages
• 🔬 Macrophages try to destroy the ink but can't, so they isolate it
• 🎨 Your tattoo fades over time as some ink escapes the macrophages
• 💉 Laser removal breaks up the particles, but new macrophages rush in
• ❤️ Your immune system fights to keep the ink in place because it loves you
• 🔎 Understanding your body requires exploring science interactively
• 🤖 Brilliant's new course demystifies AI language models like ChatGPT
• ✏️ Brilliant gives you tools to grasp how everything scientific fits together
• 🔬 The first 200 people get 20% off Brilliant with the special link

Q & A

What is the conveyor belt of death in relation to skin?

The conveyor belt of death refers to the top layers of skin that are constantly being shed and replaced by new skin cells moving up from below. These top layers are mostly dead cells that form a protective barrier.

Why can't macrophages break down tattoo ink?

Tattoo ink particles are made of heavy metals and other substances that are too large and inert for macrophages to break down with acids and chemicals. The immune system has to admit defeat and instead works to trap the particles in place.

What happens to tattoo ink over time?

Over time some tattoo ink escapes from dying macrophages. Most is recaptured but not always in the exact same place, leading to fading and blurring of the tattoo.

How does removing a tattoo work?

Tattoo removal uses lasers to heat up and break tattoo ink particles into smaller pieces that can then be carried away by fluids. But new macrophages also rush in to trap any remaining particles.

Why should tattoo ink not be poisonous?

If tattoo ink spreads through the body it can be poisonous over time. So tattoo ink should use non-toxic and non-carcinogenic pigments as much as possible.

How does the immune system react to getting a tattoo?

Getting a tattoo triggers inflammation, swelling, and a massive immune response as macrophages rush to the site to contain foreign material and ink.

What role do macrophages play in tattoos?

Macrophages are unable to break down tattoo ink so they surround and contain the particles, holding them in place forever inside the skin.

Why do tattoos fade over time?

As old macrophages die some tattoo ink particles escape and spread through the body. Most are recaptured but not always in the exact same spot, leading to fading.

How deep into skin do tattoos go?

Tattoo ink has to penetrate deep into the dermis level below the dead outer skin layers in order to remain permanent.

How does skin protect the body?

Skin protects the body by constantly shedding its outermost layers which traps debris and bacteria that can then be safely discarded.

Outlines

00:00

🎨 The Conveyor Belt of Death and Immune System Drama in Your Tattoo

Paragraph 1 explains how tattoos involve piercing deep into the dermis layer under the 'conveyor belt of dead cells' on the epidermis surface. This causes massive damage, killing skin cells and possibly letting in bacteria. The immune system responds aggressively to the 'exploding fleshy world', trying unsuccessfully to destroy the tattoo ink particles which can be toxic heavy metals.

05:06

🧬 Your Macrophages Imprison the Ink Forever, Protecting You

Paragraph 2 describes how over time, macrophages in the immune system surround and engulf tattoo ink particles they can't eliminate, freezing in place to trap the particles so they don't spread through the body. This is why tattoos are permanent - the macrophages patiently hold the ink. But some ink still escapes over decades, reducing sharpness. Laser removal also challenges macrophages to recapture escaping ink.

Keywords

💡Tattoo

A tattoo is a form of body modification where ink is inserted into the skin to leave a permanent design. In the video, getting a tattoo triggers an immune response as the skin is damaged and foreign particles (ink) enter the body. The immune system tries unsuccessfully to eliminate the ink particles before finally surrounding them to contain the threat.

💡Immune system

The immune system is the body's defense mechanism against disease and foreign invaders. In the video, immune cells like macrophages rush to the site of the tattoo to defend against bacteria and contain the ink particles which they cannot eliminate.

💡Skin

Skin is the largest organ and outer covering of the human body. The video explores the different layers of skin cells, describing the "conveyor belt of death" in which older skin cells are constantly shed and replaced by newer ones from below.

💡Macrophages

Macrophages are a type of white blood cell that engulf and digest cellular debris, foreign substances, microbes, cancer cells etc. In the video, they unsuccessfully try to eliminate tattoo ink particles before surrounding them to contain the threat.

💡Inflammation

Inflammation is the body's protective response to infection or injury, marked by redness, swelling, heat and pain. Getting a tattoo triggers inflammation as the skin is wounded and flooded with ink chemicals.

💡Healing

Healing refers to the body's natural process of regenerating and repairing damaged tissue. After getting a tattoo, the puncture wounds heal as skin cells proliferate to close gaps, though some ink particles remain trapped forever.

💡Fading

As a tattoo ages, it often fades and loses vibrancy as some ink particles escape macrophage containment over time. Fading can also be induced through laser removal which breaks up ink particles.

💡Infection

Infection refers to the invasion and multiplication of pathogen microorganisms like bacteria inside the body. Tattooing risks infection if tools are not properly sterilized, allowing bacteria to enter skin wounds.

💡Scarring

Scars occur when skin is damaged faster than normal healing can replace cells. Tattoos risk scarring if they penetrate too deeply or cause excessive inflammation and swelling.

💡Toxicity

Toxicity refers to the level of poisonousness or danger from chemical substances. Tattoo ink can contain heavy metals and other toxic ingredients which the video warns should ideally not spread through the body.

Highlights

Your skin is a conveyor belt of death, with new cells constantly pushing old ones to the surface.

Tattoos go deeper than dead skin cells, into the active layers where immune cells reside.

Tattooing rips holes in the skin, kills cells, and allows in bacteria, triggering an immune response.

Macrophages try unsuccessfully to destroy tattoo ink particles, which are too big or inert.

With no way to eliminate the ink, immune cells envelop and trap particles to contain them.

A fresh tattoo has vibrant ink sitting in damaged skin that slowly heals around it.

Over time, some ink escapes and spreads through the body or makes tattoo edges blurry.

Laser removal breaks ink into smaller pieces, but new immune cells still try to contain it.

Macrophages sacrifice themselves to imprison tattoo ink and protect the body.

Seeing your immune system respond shows how much your body tries to care for you.

Kurzgesagt made interactive science lessons with Brilliant exploring popular video topics.

Brilliant's new course demystifies AI language models like ChatGPT.

The course lets you tune models and understand why training data impacts output.

You can start Brilliant's free 30-day trial through a special Kurzgesagt link.

Brilliant gives interactive tools to see how scientific concepts interconnect.

Transcripts

Your tattoos are inside your immune system,  literally. With each very tasteful piece of art,  

you kick start a drama with millions of deaths,  

grand sacrifices and your immune system  stepping in to protect you from yourself.  

Let's give you a tattoo and zoom in  to see what happens inside your skin.

The Conveyor Belt of Death

Your skin has to solve a huge problem – it's your  largest organ and has the most direct contact with  

the world around you. Trillions of microbes, dirt,  insects and vermin can’t be allowed to get inside you

– but your skin is also constantly  damaged by you moving through the world.

Your body solved this by making your skin a  conveyor belt of death. All the skin you see  

is actually dead stuff. The alive part of your  skin cells begins around one millimeter deep,  

in the skin industrial complex. Stem cells  constantly clone themselves producing new  

skin cells that begin a journey  from the inside to the outside.

Each new generation pushes the older ones  further up. As your skin cells mature,  

they interlock with each other and produce  Lamellar bodies, tiny bags that squirt out  

fat to create a waterproof coat that  closes any gaps between them.

And then,  they dry out and kill themselves,  merging together into inseparable lumps.

This wall of dead corpses is consistently  pushed upwards. Up to 50 layers of dead  

cells cover your whole body and are constantly  replaced by new cells moving up. Every hour,  

you shed around 200,000,000 dead skin cells and  all the dirt or bacteria that are stuck to them.

Tattooing this part of your skin would be  

useless as nothing would stick  around. We need to go deeper.

When the Fleshy World Explodes

Below the conveyor belt of death lies the  dermis. It's full of structural tissue and cells,  

tiny blood vessels, sensory cells that report  to nerve endings, the roots of your hairs,  

sweat glands regulating your temperature.  And of course loads of immune cells,  

guarding your flesh right  below the moving border wall.

This region and below is where  your new tattoo will go. Ok! Ready?

The world explodes. Half a dozen monoliths  the size of skyscrapers slam through the fifty  

layers of dead cells, deep into the dermis,  ripping huge holes into the skin – only to  

retreat and smash through the tissue again  about twice a second. Tens of thousands  

of cells are violently killed right away,  ripped into pieces or damaged beyond repair.

Luckily, you did your research and chose  a responsible tattoo artist who properly  

disinfected their tools and your skin. But  you only ever get 99.9% of all bacteria,  

and some of the survivors made it into your flesh. 

To put it mildly, your immune system is not  amused at all! All the death and destruction  

wakes up hundreds of thousands of Macrophages in  your dermis, that rush into the open wounds to  

defend you. Immediately they start killing  bacteria, release chemicals that call for  

reinforcements and order your blood vessels to  open up and make your dermis swell up with fluid.

But worse than the hundreds of wounds  and a few invaders is the tidal wave  

of chemicals that floods your tissue. Tattoo  ink can be made from hundreds of substances,  

some may even be toxic or carcinogenic.  Most are from heavy metals like lead,  

nickel or chromium dissolved in distilled water.

The battlefield is now a wild mix of  dead cell parts, a few panicked bacteria,  

blood and bodily fluids, platelet  cells trying to close wounds,  

more and more fresh immune cells  and the flood of tattoo ink.

On the scale of your cells, clumps of  ink particles are huge – if you were  

the size of a cell, they’d range from  big dogs to small office buildings.

Your immune system has one main job: Identify  what is not you and smash it until it's dead.  

The Macrophages are desperately  trying to do that. Like tiny octopuses,  

they extend arm-like structures and begin  pulling the ink particles inside. Usually,  

when a Macrophage has eaten an enemy, it showers  it in acid to dissolve it. But this doesn’t work  

with the ink. They try and try but nothing  works, the particles don't react in any way.

And this is just the particles  small enough to be devoured.

By now the larger chunks are surrounded by thousands of your structural skin cells

and macrophages that are nomming on them,  bathing them in acid and attack chemicals  

trying to destroy and kill them. But  they are not moving even a tiny bit.

Nothing works!

Finally your immune system has to concede. It  will not win this fight – so it does the next  

best thing: Not lose. Your cells don’t know  how dangerous these metals and chemicals are,  

but they can at least not let them spread  around. So they just stay in place. They  

vacuum up all the particles they can fit  into their bodies and surround the larger  

ones trapping them in the only prison they can  build: themselves. Bit by bit, the ink inside  

thousands of tiny wounds moves inside millions  of immune cells that freeze in place forever.

On the outside you don’t notice any of  this. Your new tattoo is fresh and the  

colours vibrant. Your skin hurts and is  irritated and swollen. But wounds heal,  

tiny holes close, dead cells are replaced. Bit  by bit, the conveyor belt of death does its job,  

shedding dead cells ripe in colour, replacing  them with fresh and clean ones. Your tattoo  

becomes a little less vibrant, now the ink  is no longer on your skin but inside it.

But what you are really seeing  is millions of your Macrophages,  

sitting in your dermis, patiently holding  the ink in place, protecting your body  

from poison. Your immune system  is why your tattoo is forever.

Actually Nothing is Forever

Over time your Macrophages get old and die  and new ones come in to gobble up the ink  

and keep it in place. But sometimes  a tiny bit of ink escapes. Most of it

is recaptured and locked in place,  but not always the exact same place.

You notice that as your tattoo fades out a bit  and turns less sharp and crisp at its edges.  

Some of the ink escapes the tattoo entirely.  It rides fluids flowing from your tissue  

and spreads around your body, another reason  why tattoo ink should ideally not be poison.

Your immune system also kind of doesn’t want  you to remove tattoos – to do that usually the  

ink is shot at with lasers, which heats up the  particles until they break into smaller chunks,  

cooking your brave Macrophages in the  process. With every round of lasering,  

more of your tattoo is broken down and  carried away by fluids. But also every time

new Macrophages rush into the tattoo  to lock the ink in place. So like uhm,  

maybe think about it carefully before you get the  name of your new bae tattooed, but you do you.

But if you got one, you can directly see  your immune system protecting you. This  

is how much your body loves you, which  is kind of sweet. And while tattoos are  

probably not that big of a deal for your  body if applied correctly: you now know  

about the struggle going on inside your skin  and the sacrifice of your Macrophage buddies,  

only for you to have that art forever.

To appreciate your amazing immune system,  

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