Fibrin
fibrous protein involved in blood coagulation
Fibrin (also called Factor Ia) is a fibrous, non-globular protein involved in the clotting of blood. It is formed by the action of the protease thrombin on fibrinogen, which causes it to polymerize. The polymerized fibrin, together with platelets, forms a hemostatic plug or clot over a wound site.
When the lining of a blood vessel is broken, platelets are attracted, forming a platelet plug. These platelets have thrombin receptors on their surfaces that bind serum thrombin molecules, which in turn convert soluble fibrinogen in the serum into fibrin at the wound site. Fibrin forms long strands of tough insoluble protein that are bound to the platelets. Factor XIII completes the cross-linking of fibrin so that it hardens and contracts. The cross-linked fibrin forms a mesh atop the platelet plug that completes the clot. Fibrin was discovered by Marcello Malpighi in 1666.
Role in disease
Excessive generation of fibrin due to activation of the coagulation cascade leads to thrombosis, the blockage of a vessel by agglutination of red blood cells, platelets, polymerized fibrin and other components.
Begin with the source’s own compact description: “Fibrin” is fibrous protein involved in blood coagulation. The dossier treats that line as a proposition to test through Fibrin, fibrous and protein, not as a finished interpretation.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Aug 23, 2026. The linked authority identifier is Q27205. The Library of Congress control number is sh85048029. 1 of 1 selected statements include explicit references; 1 carry qualifiers and 0 use preferred rank. The first chronological checks are 1666.
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This entry incorporates text from “Fibrin” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.