fibrin is your friend

It's science day!
Here are some fun little facts:

You have between 7 and 11 pints of blood pumping thru your system at high pressure.
What happens if you develop a tear?
That can't be good, right?

A-ha!
You've already got a process in place to take care of that. You've got platelets and proteins that act as clotting factors.

Platelets and proteins are two of the 14 players that make up the clotting team.

Fibrin.
Fibrin is a tough, filament like molecule that forms the framework of a clot. It's a little like chicken wire.

Platelets.
Platelets are tiny membrane enclosed packets of cytoplasm. Cytoplasma is the gel-like substance inside a cell. They are shaped like flattened disks. There is approximately one platelet for every 15 red blood cells you own.

Alright, now say your blood vessel wall becomes damaged and a tear developed. MILLIONS of platelets come together to form a platelet plug.

This process is triggered when a tear in the blood vessel wall exposes the collagen fibers inside it. Then your body pretty much goes, "wtf is going on over there?! Someone go check!..."

Receptors on the surface of passing platelets bind to the exposed collagen fibers. The platelets become crinkly (let's call that a technical term... crinkly) to increase their surface area and stickiness. At the same time, they release signaling chemicals that attract other platelets and trigger substances called clotting factors.

The clotting factors activate each other in a series which results in the production of fibrin.

Platelets and strands of fibrin combine into a clump that plugs the gap in the blood vessel wall. The platelets in the plug contain protein filaments like those found in muscles.

To recap:

- You have a tear
- Your body is like, "wtf..."
- This mesh is formed over the tear and platelets get all flat and sticky and yell out to all their little friends in the area to come hold hands. Eventually there are so many of them mobbing the area that the dam is in place!

a little like decoupage from the inside out for all you crafty people out there.

This is the cool part.

You know how when you get a cut, you can see the skin pulled in towards the center of the cut. How it tightens?

That's because after this process is done - the platelets in the plug SHRINK!
The filaments contract, shrinking the plug and pulling the sides closer together.

It is...GENIUS.

Then your immune system cells move in under the clot to play bouncer and clear away any invading pathogens.

So, fibrin is truly your friend. Pretty much anything that prevents you from bleeding to death is your friend.

There are about 2 trillion platelets in the blood plus another trillion in reserve in the spleen. A platelet lives for 10 days, so every day you lose and replace more than 200 billion of those little suckers.