Learning about the coagulation cascade might sound intimidating, but it’s actually a fairly easy to understand part of the healing process. Learn more!

There are thirteen different clotting factors involved in the coagulation cascade. This doesn’t even count the cofactors and inhibitors etc.

Many students take one good look at that diagram and start thinking about studying something else. Memorizing each and every step forward and backward is time-consuming. What is more important in the long run is that understand it.

Don’t be intimidated by complicated graphs and confusing lectures. Keep reading for an easy-to-understand explanation of the coagulation cascade.

Bombo Clot

The process of coagulation is the process in which blood clots are formed. When something coagulates, it goes from a liquid state to a gel or solid.

To make cheese curds, you need to coagulate milk using a culinary process known as curdling. People across the world make a number of delicious dishes this way.

Come to think of it, blood sausage (morcilla) is basically just coagulated blood. Before we get any hungrier, let’s get back to the lesson.

Hematology and You

You have about a gallon and a half of premium blood pumping through your arteries and veins. The blood plays numerous vital functions in the human body.

Perhaps, the most imminently vital of these is to transport erythrocytes, aka red blood cells (RBCs), to the different tissues and organs. RBCs ‘pick up’ oxygen from the lungs and ‘carry it’ using a molecule called hemoglobin.

Without oxygen, your cells will die and so will you. So, you can see why it’s imperative that our blood vessels can function properly.

Keeping The Blood Where It Belongs

Hemorrhage is the scientific term for blood loss. It refers to the rupture of a vessel and the resulting loss of blood.

The blood doesn’t necessarily have to leave the body, as is the case with internal bleeding, bruising, hematomas.

In most injuries, the blood vessels are able to repair themselves relatively quickly. This is thank to, in large part, the effects of coagulation

Stopping Power

Hemostasis (not to be confused with homeostasis) refers to the mechanisms the body uses to stop bleeding. It is the opposite of hemorrhage.

Before coagulation itself can occur, a few things need to happen.

The Main Squeeze

Let’s imagine that you were walking barefoot and cut your foot on some glass. It’s not a huge gash but you’re definitely bleeding and in pain.

The initial response (after yelling an expletive) is to undergo vasospasm. Remember, blood vessels contain a layer of smooth muscles that allow them to dilate and contract. This allows them to regulate your blood pressure and send more blood to certain parts of the body as needed.

Vasospasm is sudden, prolonged vasoconstriction. In this case, the affected blood vessel in your feet will contract to reduce blood loss.

Meet the Plug

Now that your vasculature has put some pressure on the wound, so to speak, it’s time to plug the leak.

Earlier we mentioned the RBCs, your blood also contains platelets (thrombocytes). These are fragments of cells that are derived from the jumbo-sized megakaryocytes.

They might not have a nucleus but they are smart enough to find the damaged endothelium (inner wall of the blood vessel). They form a plug and release adenosine phosphate, thromboxane, and serotonin to increase vasoconstriction and call for more platelets.

Coagulation and Culmination

The platelet plug is slowing the bleeding but it’s not quite enough. It’s kind of like stopping water with a net.

Now, it’s time for coagulation to occur. The coagulating blood is not able to pass through the platelet plug reinforced with fibrin. It’s like a clog in a sink.

Once the clot has served it purpose, it then dissolves so normal function may resume.

Making Sense of the Coagulation Cascade

The coagulation cascade is a metabolic pathway in which certain peptides undergo changes for clot formation to occur.

What are peptides? They are relatively short chains of amino acids. Think of them as simple mini-proteins.


The clotting factors are found in their unactivated form circulating throughout the blood. They can become activated through the intrinsic or the extrinsic pathway. Either way, the end in the common, final pathway.

Also called the contact activation pathway, this begins when blood vessel is damaged. It starts with high-molecular-weight kininogen (HMWK), kallikrein, and factor XII.

Then, factor XI and factor IX are activated. Activated factor IX, factor VIII, calcium, and platelet phospholipids form a complex to activate factor X.


The extrinsic pathway begins when tissue factor activates factor VII. Activated Factor VII activates factor X.

See? That wasn’t so bad. Umbrella labs do a great job demonstrating this with the coagulation cascade diagram. Check it out.


The common pathway starts with activated factor X. This converts prothrombin to thrombin which, in turn, converts fibrinogen to fibrin.

This results in a stable fibrin clot.

Not Too Little, Not Too Much

Blood clots are essential in preventing and controlling blood loss. On the other hand, uncontrolled coagulation can be life-threatening.

If a blood clot completely occludes a given vessel, the tissues it supplies won’t receive as much oxygenated blood. Some people have a predisposition to form clots due to genetic factors and/or medical conditions.

Just like you have coagulation factors, you also have proteins that are in charge of cleaning up after.

Don’t Go Chasing Cascades

The coagulation cascade can difficult to navigate at first glance. All the branches and activating factors are tricky to memorize.

However, if you understand how it works, it will help when you are learning about bleeding disorders, pharmacology, and how to interpret a blood coagulation test.

Hopefully, this guide cleared a few things up. Visit our blog for more articles about health and science.