Factor I

Fibrinogen

Made in the liver

Active form-fibrin

Cross links plts in aggregation

Absorbed in platelets alpha granules

Acute phase reactant

Increased w/pregnancy & smoking

High fibrinogen assoc w/MI & stroke

Low/dysfunctional assoc w/bleeding

Dysfunctional assoc w/thrombosis

Factor II

Prothrombin

Made in liver

One of Magic 4 (II,VII,IX,X)

Vit K dependant

Activated by "Prothrombinase complex"

Active form is thrombin

Responsible for conv of Fbg to Fibrin

Factor III

Tissue Factor III ( TFIII)

Found in all tissues

Esp brain,liver,lung,placenta

Released from injured tissues

Cofactor for activation of Factor VII

No known deficiency

Factor IV

Calcium - Ca ⁺⁺

Mediator of platelet activation

Required in several steps of cascade

Low Ca⁺⁺ not a problem w/invivo hemostasis

With coag screening tests must add Ca⁺⁺ to overcome anticoagulant

Factor V

Labile Factor

(Both V and VIII are labile)

Activity decreses rapidly at RT

Made in the liver

Attaches to receptor on activated platelets

Thrombin modifies or activates Factor V

Works in complex with Xa, Ca⁺⁺ and PF3to activate prothrombin

Inactivated by Protein C

Factor VI

(psych)

Factor VII

Proconvertin or Stable Factor

Made in the liver

One of the Magic 4 (II,VII,IX,X)

Vit K dependant

Activated by factors XIa or VIIa (alternate pathway)

Works in complement with VIIIa, Ca⁺⁺, and PF3 to activate factor X

Factor IX deficiency → Hemophilia B

(2nd most common)

Factor VIII

vonWillibrand Factor Complex

VIII is the coagulant or clottable portion

(AHF or VIII:C)

Produced in several tissues-mostly liver

Heat labile

Thrombin modifies or activates VIII (VIIIa)

Works in complex with IXa,Ca⁺⁺, and PF3 to activate Factor X

VIII Deficiency → Hemophilia A

Factor VII is unstable when not bound to vMF

Inactivated by Protein C

Factor VIII

vonWillibrand Factor Complex

(continued)

vWF is the carrier molecule for VIII:C

Produced by megakaryocytes and endothelial cells

Platelet adhesion to collagen

Deficiency in vWF → vonWillebrands Disease

DDAVP is a drug that stimulates the release of vWF from endothelial cells

Factor IX

Christmas Factor

Made in the liver

One of the Magic 4 (II,VII,IX,X)

Vit K dependant

Activated fu Factors XIa or VIIa ( alternate pathway)

Works in complex with VIII(a),Ca⁺⁺, and PF3 to activate Factor X

Factor IX deficiency → Hemophilia B

(2nd most common Hemophilia)

Factor X

Stuart-Prower

Made in the liver

One of the Magic 4(II,VII,IX,X)

Activated by complexes (Extrinsic and Intrinsic Tenase)

Works in complex with V(a),Ca⁺⁺, and PF3 to activate prothrombin

Made in the liver

Contact factor

Travels in blood complexed with high molelcular weight kininogen(HMWK)

Activated by Factor XIIa

(alternate activation by thrombin and autoactivate invitro by glass)

Only contact factor that a deficiency causes bleeding → Hemophilia C

Factor XII

Hageman Factor

Made in the liver

Contact factor

Activated by contact with subendothelial tissue

Activates XI with cofactor HMWK

XIIa also activates prekallilren to kallikrein

Kallikrenin can activate kinin & fibrinolytic pathways

Factor XII deficiency DOES NOT cause bleeding

Prekallikrein (PK)

Fletcher Factor

Made in the liver

Contact Factor

Activated by XIIa

Attached to HMWK (is a cofactor for PK activation)

Activates: more XII

Plasminogen to Plasmin

Hydrolyzes bradykins from HMWK to initiate kinin system

PK deficiendy does not cause bleeding

(usually asymptomatic)

Factor XIII

Fibrin Stabilizing Factor

Made in the liver

Contact factor

Complexes with XI and PK

Cofactor with XIIz to activate XI

Acts to a substrate for kallikrein in the production of kinins

(usually asymptomatic)

Increase vascular permeability

Contract smooth muscle

Dilate small blood vessels

Induce pain and inflammation

Release prostaglandins from tissues

Phospholipid surface that supports coagulation cascade

Provides binding site for Vit K dependant factors