Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Fibrin is a protein that plays a crucial role in blood clotting, forming a fibrous mesh that impedes blood flow at the site of injury. It is created by the action of the enzyme thrombin on fibrinogen, a soluble protein found in blood plasma.
The physiological process that stops bleeding at the site of an injury, involving blood vessel constriction, platelet plug formation, and blood coagulation.
A small cell fragment without its own nucleus, circulating in the blood and involved in clot formation by adhering to other platelets and damaged tissue