Blood Clotting Pathways: Extrinsic and Intrinsic (Free Notes, Practice Quiz & FAQs)

Introduction

Coagulation, another name for the intriguing process of blood clotting, prevents excessive bleeding after cuts or other injuries.

The two main blood clotting pathways:

• The extrinsic pathway
• The intrinsic pathway

These will be dissected in this article with concise explanations and bullet points by making everything simple to grasp.

The Extrinsic pathway

When it comes to fast response, the extrinsic pathway is the blood clotting super hero.

1. Injury Found at the Trigger Point:

The blood vessels in an injury or cut are harmed. A substance known as tissue factor is released by cells around the injured area.

2. Tissue Factor Requests Assistance:

The extrinsic route is started by tissue factor. It makes the blood’s clotting protein Factor VII active.

3. The Cascade Begins in the Domino Effect:

A series of events known as the clotting cascade are triggered by factor VII. Factor X is activated as a result of this chain of events.

4. Production of Thrombin:

To create thrombin, factor X mixes with other clotting factors. The mastermind behind blood clotting is thrombin.

5. Formation of Fibrin

The function of thrombin is to change fibrinogen, a soluble protein, into fibrin threads, which are insoluble. A clot is made when fibrin meshes with blood cells to form a mesh.

6. The Birth of the Clot:

A blood clot you have prevents the bleeding.

Intrinsic pathway

The intrinsic pathway, which functions inside your blood vessels, is more akin to a backup plan.

1. Begin within the vessels

The intrinsic pathway begins inside your blood vessels, in contrast to the extrinsic pathway.

Hageman Factor Kickstarts Things:

The main player in this scenario is the Factor XII also called as Hageman Factor. When it comes into contact with the blood vessel wall’s exposed collagen, it becomes active.

3. The Cascade Keeps Going:

A cascade starts, exactly as it starts in the extrinsic pathway. Factor XII makes Factor XI active.

4. Generating Thrombin

Factor XI works in tandem with Factors IX, VIII, and IX in order to activate the Factor X.

5. Take the Well-Traveled Route:

Factor X then causes thrombin to be activated, turning fibrinogen into fibrin.

6. The Clot Prevails:

A blood clot is formed when fibrin mesh develops.

Learn more about this topic here. Free handwritten notes, FAQs and Practice Quiz Included.