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Pathology Outlines - Intrinsic / extrinsic / common pathway

source : pathologyoutlines.com

Pathology Outlines – Intrinsic / extrinsic / common pathway

Coagulation

Physiology

Intrinsic / extrinsic / common pathway

Topic Completed: 1 June 2012

Minor changes: 9 March 2021

Copyright: 2002-2021, PathologyOutlines.com, Inc.

PubMed Search: Common pathway [title] coagulation

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Cite this page: Parsons JC. Intrinsic / extrinsic / common pathway. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/coagulationcommonpathway.html. Accessed April 19th, 2021.

Common pathway

Involves fibrinogen (factor I), factors II (prothrombin), V, X
Thrombin converts soluble fibrinogen to insoluble fibrin
Releases fibrinopeptides A and BRemaining fibrin monomers polymerize to form fibrin
Thrombin also binds to antithrombin, which inhibits thrombin to prevent excessive clotting
Thrombin may also activate factor XI (part of intrinsic pathway), factors V, VIII, XIII, XI and platelets
Factor XIII cross links fibrin to increase stability of fibrin clot
While both PT and aPTT include the common pathway, the PT is a more sensitive screening test for common pathway problems
References: Blomback: Essential Guide to Blood Coagulation, 1st Edition, 2010

Extrinsic pathway

Involves tissue factor (TF), originally considered “extrinsic” to blood since it is present on cell surfaces not normally in contact with (i.e. extrinsic to) the circulatory system
The primary mechanism of the coagulation pathway in vivo is tissue factor binding to activated factor VII (factor VIIa)
TF-Factor VIIa complex activates factors X and IX (though in vivo it appears to first involve factors VIII and V from the intrinsic pathway, which then activate factors X and IX)
Activated factor IX activates more factor X, with cofactors activated factor VIII, anionic phospholipids (from activated platelets) and calcium
Activated factor X converts prothrombin to thrombin, with activated factor V, anionic phospholipids (from activated platelets) and calcium as cofactors
After initial activation, pathway is inhibited by the binding of tissue factor pathway inhibitor (TFPI) to factor Xa, which inhibits TF-Factor VIIa complex, and further coagulation is dependent on the intrinsic pathway
Merges with extrinsic pathway into common pathway
The prothrombin time (PT) measures the extrinsic and common pathways
References: Kolde: Haemostasis: Physiology, Pathology, Diagnostics, Limited Edition, 2004

Intrinsic pathway

Involves factors VIII, IX, XI, XII (Hageman factor), prekallikrein, high molecular weight kininogen (Wikipedia – Coagulation)
Merges with extrinsic pathway into common pathway
Activated when factor XII binds to negatively charged “foreign” surface exposed to blood
Then sequentially activates factors XI, IX, X, then factor II (prothrombin to thrombin), which converts fibrinogen to fibrin (see common pathway)
Once extrinsic pathway is inhibited by TFPI-Xa complex (see extrinsic pathway), factor VIIIa / IXa complex becomes dominant generator of factor Xa, thrombin and fibrin
Factor XIIa also converts prekallikrein to kallikrein, which activates more factor XIIa
Both require high molecular weight kininogen as cofactorsKallikrein also releases bradykinin from high molecular weight kininogen, which causes vasoconstriction
The activated partial thromboplastin time (aPTT) measures the intrinsic and common pathways
References: Kolde: Haemostasis: Physiology, Pathology, Diagnostics, Limited Edition, 2004

Diagrams / tables

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Common Pathway (Coagulation) - Perfusion.com

Common Pathway (Coagulation) – Perfusion.com – Common Pathway (Coagulation). February 18, 2011 / No Comments. AddThis Sharing Buttons. The endpoint of activity for both the extrinsic and intrinsic pathways for coagulation is the activation of factor X. Reactions beyond this point are common to both pathways, and involves the combining of…Common pathway activator: Viper venoms, e.g. Russell's viper venom, can activate factor X. Thrombin can be used to measure the thrombin clot time Activated coagulation time (ACT). A diatomaceous earth ACT tube. The ACT is a useful screen for evaluation of the intrinsic and common pathways…Modern coagulation pathway. Hand-drawn composite from similar drawings presented by Professor Dzung Le, MD, PhD, at UCSD Clinical The coagulation cascade is therefore classically divided into three pathways. The tissue factor and contact activation pathways both activate the "final common…

Coagulation assays | eClinpath – Coagulation Cascade. Intrinsic Pathway. Contact System. AT III. Fibrin. Common Pathway Degradation. Action of an enzyme. Enzymatic conversion of substrate to product….that factor 2 located in common pathway of coagulation cascade, so inhibition of factor 2 or any factor in common pathway will prolong both PT and PTT, so this mean that heparin has indirect effect on extrinsic pathway and warfarin has…The extrinsic pathway for coagulation starts with the trauma to the vascular wall or surrounding tissue They just both end up making activatated Factor 10. Edit. Some extra things and clarity. The common pathway of blood clotting starts. The Hidden Divine Message: Do you see easy mathematics?

Coagulation assays | eClinpath

Coagulation – Wikipedia – Intrinsic pathway enters into a common pathway of blood coagulation after activating prothrombin activator. When prothrombin activator is activated, it facilitates the Both pathways proceed towards the formation of prothrombin activator or the factor X. Both pathways end up in a common pathway.Blood coagulation pathways in vivo showing the central role played by thrombin. Coagulation begins almost instantly after an injury to the blood vessel has damaged the endothelium lining the blood vessel. They join end to end and they create a fibrin strand. So the question then becomes, how do…Aka: Clotting Pathway, Clotting Cascade, Coagulation Pathway, Clotting Factor, Coagulation Factor. Vitamin K is required for carboxylation of terminal ends of coagulation proteins. Factors in the blood that are essential for blood coagulation. The absence or mutation of these factors can lead…

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