How The Immune System ACTUALLY Works – IMMUNE

The human immune system is the most complex biological system we know, after the human brain,

and yet most of us never learn how it works.

Or, what it is.

Your immune system consists of hundreds of tiny—and two large—organs.

It has its own transport network spread throughout your body.

Every day, it makes hundreds of billions of fresh cells organized like an army.

With soldiers, captains, intelligence officers, heavy weapons, and crazy suicide bombers.

It's not some sort of abstract entity.

Your immune system is you.

Your biology protecting you from the billions of microorganisms that want to consume you,

and from your own perverted cells that turn into cancer.

It's so manifold that it's impossible to cover in one video,

so we'll make a series looking at different aspects of it.

Today: What happens when your body is invaded

and your first lines of defenses are engaged in a fight for life and death.

It's been a normal day,

when suddenly the world explodes and an asteroid rips the sky open.

Countless alien life forms invade,

ready to destroy cities and infrastructure, and eat civilians...

Or, this is what your cells experience.

You look at your bleeding thumb that you just cut on a dirty twig in the park.

How annoying!

But inside the wound, a horrible catastrophe has happened.

There are dead cells, and blood and dirt everywhere.

Even worse, countless bacteria invade the warm caverns between your helpless cells

to explore their new home, steal your resources, and poop everywhere.

Immediately, the first stage of your defense kicks in.

The cells that survive the impact, or are hurt or dying, scream in panic

releasing an onslaught of chemical alarm signals that awaken your immune system.

The first cells to show up are macrophages.

If an average cell were the size of a human, a macrophage would be the size of a black rhino.

A stoic cell in principle but you wouldn't want to annoy it.