Clotting Factors List – Names, Numbers and Actions (Functions)

What are clotting factors?

The clotting factors are the group of chemicals that are constant circulation in the blood or present in tissues of the blood vessels. These compounds are responsible for the formation of a blood clot. Clotting factors are usually inactive but once there is tissue injury to the wall of the blood vessel, the first factor is activated. This has a cyclical effect with each factor activating the next. The ultimate aim is for these clotting factors to eventually convert the necessary components that will form a blood clot.

Functions of Clotting Factors

Hemostasis is the body’s mechanism to stop blood loss. It is made up of several mechanisms with the coagulation phase involving the clotting factors and the formation of a blood clot. The series of reactions whereby one clotting factor activates the next is known as the coagulation cascade. The clotting factors eventually convert fibrinogen to fibrin which then forms a mesh network at the site of injury. This traps blood cells and other components to form a firm blood clot and thereby completely stop blood loss. Therefore the function of clotting factors are to trigger the formation of a blood clot and stabilize it for as long as necessary. Clotting factors are therefore known as procoagulants.

List of Clotting Factors

Factor I

Name : Fibrinogen
Source : Liver
Pathway : Both extrinsic and intrinsic
Activator : Thrombin
Actions : When fibrinogen is converted into fibrin by thrombin, it forms long strands that compose the mesh network for clot formation.

Factor II

Name : Prothrombin
Source : Liver
Pathway : Both extrinsic and intrinsic
Activator : Prothrombin activator
Actions : Prothrombin is converted into thrombin which then activated fibrinogen into fibrin.

Factor III

Name : Thromboplastin / Tissue factor
Source : Platelets (intrinsic) and damaged endothelium (cells) lining the blood vessel (extrinsic).
Pathway : Both extrinsic and intrinsic
Activator : Injury to blood vessel
Action : Activates factor VII (VIIa).

Factor IV

Name : Calcium
Source : Bone and absorption from food in gastrointestinal tract
Pathway : Both extrinsic and intrinsic
Action : Works with many clotting factors for activation of the other clotting factors. These are called calcium-dependent steps.

Factor V

Name : Proaccerin / Labile factor / Ac-globulin (Ac-G)
Source : Liver and platelets
Pathway : Both extrinsic and intrinsic
Activator : Thrombin
Action : Works with Factor X to activate prothrombin (prothrombin activator).

Factor VII

Name : Proconvertin / Serum prothrombin conversion accelerator (SPCA) / stable factor
Source : Liver
Pathway : Extrinsic
Activator : Factor III (tissue factor)
Actions : Activates Factor X which works with other factors to convert prothrombin into thrombin.

Factor VIII

Name : Anti-hemoplytic factor / Antihemophilic factor (AHF) or globulin (AHG) / antihemophilic factor A
Source : Endothelium lining blood vessel and platelets (plug)
Pathway : Intrinsic
Activator : Thrombin
Actions : Works with Factor IX and calcium to activate Factor X.
Deficiency : Hemophilia A

Factor IX

Name : Christmas factor / Plasma thromboplastin component (PTC) / Antihemophilic factor B
Source : Liver
Pathway : Intrinsic
Activator : Factor XI and calcium
Actions : Works with Factor VIII and calcium to activate Factor X.
Deficiency : Hemophilia B

Factor X

Name : Stuart Prower factor / Stuart factor
Source : Liver
Pathway : Extrinsic and intrinsic
Activator : Factor VII (extrinsic) / Factor IX + Factor VIII + calcium (intrinsic)
Actions : Works with platelet phospholipids to convert prothrombin into thrombin. This reaction is made faster by activated Factor V.

Factor XI

Name : Plasma thromboplastin antecedent (PTA) / antihemophilic factor C
Source : Liver
Pathway : Intrinsic
Activator : Factor XII + prekallikrein and kininogen
Actions : Works with calcium to activate Factor IX.
Deficiency : Hemophilia C

Factor XII

Name : Hageman factor
Source : Liver
Pathway : Intrinsic
Activator : Contact with collagen in the torn wall of blood vessels
Actions : Works with prekallikrein and kininogen to activate Factor XI. Also activates plasmin which degrades clots.

Factor XIII

Name : Fibrin stabilizing factor
Source : Liver
Activator : Thrombin and calcium
Actions : Stabilizes the fibrin mesh network of a blood clot by helping fibrin strands to link to each other. Therefore it also helps to prevent fibrin breakdown (fibrinolysis).

Prekallikrein

Source : Liver
Pathway : Intrinsic
Actions : Works with kininogen and Factor XII to activate Factor XI.

Kininogen

Source : Liver
Pathway : Intrinsic
Actions : Works with prekallikrein and Factor XII to activate Factor XI.