You Are Immune Against Every Disease

You Are a Planet#

Alright, so picture this: you’re not just one person, right? You’re actually like a giant planet made up of roughly 40 trillion cells. That’s a crazy huge number! If you could somehow turn each of your cells into a human being, you’d end up being as massive as 20 Mount Everests stacked up!

For all the tiny, creepy crawly inhabitants that live inside you, your body is basically a dream come true. It’s an ecosystem packed with goodies – plenty of resources, warmth, and space. A perfect spot for them to move in, settle down, and maybe even start a family. Now, while some of these little guests are totally fine to have around, honestly, most of them are definitely not welcome.

Your Immune System: The Planet’s Guardian#

This is where your immune system steps in. Think of it as the big guardian of your planet. Its main job is to protect all your cells from the constant threat of invasion. It’s always on guard.

The Enemy’s HUGE Advantage#

Here’s where things get a bit tough. Your enemies in this tiny world have a massive advantage. It all comes down to how fast they can multiply compared to you.

Making a Human: Think about how much effort goes into making just one copy of yourself (one human with trillions of cells).
- First, you gotta find someone who actually thinks you’re cute.
- Then comes the dating and all that awkward stuff.
- If things somehow work out, two of your cells do a super complicated dance and merge.
- After that, you wait for months while that single cell multiplies over and over.
- Eventually, a new human is born, but it’s just a mini copy that takes years to become even slightly useful.
Making an Enemy: Now look at your tiny invaders:
- A bacterium is just one cell. It can make a fully grown copy of itself in about half an hour.
- A virus can explode into hundreds of copies within just a few hours, and billions in a matter of days.

See the difference? Your enemies multiply orders of magnitude faster than you do.

Constant Evolution#

And it gets worse. Because bacteria and viruses go through so many generations so incredibly quickly, your body acts like a tough environment, pushing them to change (selective pressure). By sheer luck and chance, eventually, one of these tiny individuals will have a random change (mutates) and adapts in just the right way to shrug off your defenses. Then, boom, it multiplies like crazy again.

What this means is you’re up against a seemingly endless variety of different enemies. And you’re just too slow to keep up with how fast they change and evolve. Yeah, that sounds pretty bad.

Luckily, The Immune System is Amazing#

But don’t worry, your immune system is one of the most incredible things ever! It’s actually considered the second most complex biological system we know of, right after the human brain itself. It’s so mind-blowingly sophisticated that we still haven’t figured out all its secrets.

Because it’s so complicated, we’ll have to simplify things a bit and focus on one part at a time to get a handle on it. (If you want the whole massive story, keep an eye out for an announcement at the end of the video).

Two Immune Systems Are Better Than One#

So, how come we’re not all wiped out by some brand new super-bug? Well, in simple terms, you actually have two immune systems:

The Innate Immune System: This one was good to go the moment you were born. It’s mostly made up of general-purpose soldiers, like the ones introduced in the last immune video.
The Adaptive Immune System: This system uses two specific types of cells, called T-cells and B-cells. These are your super weapons, incredibly effective and absolutely deadly for your enemies. These cells are tricky and take a while to build and get ready, but when they are, they pack a serious punch.

The Adaptive System’s Super Library#

What makes your adaptive immune system so incredibly powerful? It has what you could call the largest library in the universe. It seems to have an answer for everything.

Seriously, you have at least one of these super weapon cells ready inside you right now, capable of fighting things like:

The Black Death (from history!)
The Corona virus (the one causing COVID-19)
And even the first deadly bacteria that might show up in a city on Mars a hundred years from now!

This huge capability is precisely what lets you counter the crazy fast changes and evolution of bacteria and viruses. But how on Earth is this even possible?

Understanding the Microworld Language: Proteins#

To get a grip on this, let’s take a step back. Every living thing on Earth is built from the same basic stuff, mostly proteins. Proteins are like the fundamental building blocks of life, and they can come in billions of different shapes. Imagine them like 3D puzzle pieces – there are billions of different ones.

Your enemies, the bacteria and viruses, use these protein puzzle pieces to build their own bodies. Why is this important? Because, in a way, proteins are the language of the microworld. Cells don’t have eyes or ears to see who’s who. To tell a friend from an enemy, they have to physically touch them and figure out if the protein they’re touching belongs to a friend or a foe.

Recognizing Friend from Foe: Receptors#

How do they “figure it out”? Well, cells have countless tiny gadgets on their surfaces called receptors. These receptors are specifically designed to connect with or “recognize” a particular protein puzzle piece.

So, your cells have these tiny puzzle pieces (receptors) on their outsides that can click together with or recognize other protein puzzle pieces they bump into. When one of your cells touches a protein, connects with it, and recognizes it as belonging to an enemy, it instantly knows: “Okay, time to attack!”

Your immune system can only fight off an invader if its cells can make this crucial distinction between Friend or Foe using these proteins and receptors.

The Problem with Billions of Pieces#

Here’s the catch: since there are billions of possible protein puzzle pieces out there, that means there are also billions of possible enemy puzzle pieces your immune system might encounter. This is a big part of why diseases like the flu keep coming back every year. The influenza virus changes (mutates) super fast, so the proteins making up its outer shell are constantly changing just a little bit.

The general soldiers of your innate immune system have a bunch of these protein puzzle pieces for common bacteria and viruses already “memorized.” That’s why they’re good all-purpose fighters. But they just aren’t effective against the countless billions of tiny mutations and adaptations that your enemies can come up with.

The Adaptive System’s Cheat Code for Variety#

The main reason you’re still alive and kicking despite all this is because your adaptive immune system has an incredible ability to recognize between 1 billion and 10 billion different enemy protein puzzle pieces. That huge range is enough to be prepared for pretty much every possible enemy out there.

But seriously, how is this possible? How could your immune system possibly have enough variety to be ready for every potential protein puzzle piece in the universe?

Here’s the cool part: the cells of your adaptive immune system found a clever cheat code. They mix and match their own genetic code to create this mind-blowing variety of receptors.

The really deep details are way too complex for right now, but the basic idea is that your adaptive immune cells are given special permission to take a small chunk of their own genetic code and shuffle it around in random ways. This lets them create billions of different receptor designs.

The Cook Metaphor#

Think of it like this: Imagine an army of cooks, and each one wants to invent their own unique recipe. They have 100 different ingredients they can pick from (these ingredients are like the tiny pieces of genetic code in this story).

Each cook grabs a few random ingredients and mixes them together randomly.

One might mix tomato, chicken, rice, and half an onion for an entree, then marshmallow, pepper, strawberries, and a quarter banana for dessert.
Another might grab cucumber, beef, potatoes, and two carrots, and mix them with blueberries, chocolate, and cream with a pinch of cinnamon.

Even with just slight variations and only 100 starting ingredients, you can create billions of possible recipes. It’s the same with your cells! Using just a small selection of gene fragments, your cells can whip up billions of unique receptors.

The specifics of how they do this gene mixing are so cool, they really deserve their own video or even a whole chapter in a book. But the result is amazing: by mixing up tiny gene fragments, you can get up to 10 billion different combinations.

Ultimately, you end up with billions of different immune cells, and each one has its own specific, unique receptor (like the distinct “dish” from our cook metaphor). This receptor is able to recognize one specific protein puzzle piece. When you add all these billions of cells together, you end up with at least one cell ready to recognize and fight every possible enemy that could potentially exist.

The Dangerous Problem: Attacking Yourself#

But here’s a really serious problem that comes up: If your adaptive immune system is busy making weapons (receptors) that can attack every possible protein puzzle piece in the universe, doesn’t that mean it will accidentally make some that can attack your own cells?

Yep. And this happens all the time.

This is so fundamentally dangerous to your survival that your body has a whole organ dedicated just to preventing this.

The Murder University of Your Thymus#

This special organ is called the thymus. It’s roughly the size of a chicken wing and sits right above your heart. Most people have probably never even heard of it!

Interestingly, your thymus is one reason why your immune system starts to get weaker as you get older. It’s in a constant state of shrinking and decline once you hit puberty.

But what does the thymus actually do? Think of your thymus as a kind of “Murder University” for your immune cells. Inside, your immune system puts these young adaptive immune cells through an intense and frankly, deadly training program.

Basically, the teachers in the thymus show these young cells all sorts of protein puzzle pieces that are used by your own body’s cells. They watch how the young immune cells react. If a young cell sees a body puzzle piece and recognizes it as something it wants to attack, the teacher cells immediately order that young cell to kill itself. These self-destructing cells are then eaten up and recycled by the body.

Your immune system is incredibly strict and particular about this training process. It’s so tough that around 98% of the adaptive immune cells that enter this “Murder University” actually die there! Only a tiny 2% manage to graduate and earn the right to go out and do their job of protecting you for real.

If this critical process goes wrong, and some cells escape that can recognize and attack your own body’s protein puzzle pieces, it can lead to what’s called autoimmune disease. This is where your own immune system turns on itself and attacks your body from the inside. But, like many other parts of this story, that’s a whole different topic for another time.

Quick Recap#

Let’s do a quick summary of what we’ve covered about your immune system so far:

You have two main parts to your immune defense:
- One that’s ready from the moment you’re born (the innate system).
- One that holds the largest library of super weapons in the universe but needs time to get ready (the adaptive system).
To create billions of different super weapons, your adaptive immune cells use a “cheat code”: they recombine a part of their own genetic code to build an incredible variety of attack receptors.
After they’re created, these cells enter a brutal “Murder University” (the thymus).
Only about 2% survive this intense training, specifically to make absolutely sure they don’t attack your own body.
In the end, you have billions of different specialized cells that, together, are equipped to protect you against pretty much every possible enemy you could face in the universe.

So Why Do We Still Get Sick?#

Now, you might be thinking, “Wait a minute! If all this is true, why do we ever get sick at all? How come a new disease like COVID-19 was able to kill millions of people around the world?”

Well, everything we’ve just talked about is just a tiny, tiny glimpse into the amazing, constant struggle for life and death happening inside your body every single day. There are so many incredible details and unanswered questions out there.

Like:

How does your body actually find the right immune cell (the one with the right receptor) at the right time to fight off an invader?
How do your enemies sometimes manage to fight back and overcome your amazing immune system anyway?
And what about all the other important things that just didn’t fit into this video?

Discover More in “Immune”#

Today’s the day! Everything you’re wondering about and more is explored in a brand new book called “Immune: A Journey into the Mysterious System That Keeps You Alive.” It’s written by Philip Detmer, who is the founder and head writer of Kts AR (that’s the name of the channel/creator).

The release of the book actually had to be pushed back a couple of times. First, because of problems with shipping cargo. Then, believe it or not, because so many people pre-ordered it that they didn’t have enough copies ready for the original launch day! A huge thank you to everyone who pre-ordered!

“Immune” tells the incredible, epic story of your immune system. Reading it will totally change how you think about your own body, how you feel when you’re sick, and how you appreciate being healthy. The book is written to be just as fun and easy to understand as the Kts AR videos you’ve watched, but it can dive much, much deeper into the subject matter.

It invites you to go on a journey through the hidden microverse right inside yourself. You’ll witness deadly wars fought between billions of invaders and your cells. You’ll really learn how your immune system actually works and how it protects you from everyday things like cuts, serious diseases like cancer, and viruses like COVID.

Seriously, right now, understanding how immunity works feels more important and urgent than ever before. The book “Immune” is designed to be fun to read, looks great, and apparently, it even smells good!

You can find a link in the description to order it today.

For the creator, this book marks the end of a decade-long personal journey working on this topic. So, a massive, heartfelt thank you to everyone for your support over the years, and thank you for watching and reading this!