BLOOD COAGULATION, ITS
MECHANISM DISORDERS AND
ITS ROLE IN HUMAN LIFE

Presenter: Muhammad Asad Ishaq
262/FBAS/BSBT/F12
• Blood
The fluid that circulates in the blood vessels of the body.

• Homeostasis:
Constant conditions within organisms i...
This over all process consists of 4 parts.
I.

Vascular constriction

II.

Platelet activation by thrombin

III. The clot ...
Coagulation:
The process of forming clots/semisolid
lumps in a Liquid.

Mechanism
Two pathways lead to the formation of a ...
Extrinsic Pathway:
Fibrin clot formation in response to tissue injury is the most
clinically relevant event of homeostasis...
Factors Pathway

Activities

XII

Intrinsic

Binds to exposed collagen at site of vessel wall injury.

XI

Intrinsic

Acti...
Activation of Prothrombin to Thrombin
The common point in both pathways is the activation of
factor X to factor Xa. Factor...
Disorders
Defects in the process of homeostasis, leading to bleeding
disorders, have been identified at the level of the p...
Blood Coagulation, its Mechanism Disorders and its role in Human Life
Blood Coagulation, its Mechanism Disorders and its role in Human Life
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Blood Coagulation, its Mechanism Disorders and its role in Human Life

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Blood Composition, Disorders and Coagulation and its Role in Hemostatsis.

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Blood Coagulation, its Mechanism Disorders and its role in Human Life

  1. 1. BLOOD COAGULATION, ITS MECHANISM DISORDERS AND ITS ROLE IN HUMAN LIFE Presenter: Muhammad Asad Ishaq 262/FBAS/BSBT/F12
  2. 2. • Blood The fluid that circulates in the blood vessels of the body. • Homeostasis: Constant conditions within organisms in interaction with external environment. Coagulation is a process for homeostasis of the body
  3. 3. This over all process consists of 4 parts. I. Vascular constriction II. Platelet activation by thrombin III. The clot formed IV. Fibrinolysis by Plasmin
  4. 4. Coagulation: The process of forming clots/semisolid lumps in a Liquid. Mechanism Two pathways lead to the formation of a fibrin clot: the intrinsic and extrinsic pathway. Although they are initiated by distinct mechanisms. The end product is common and Both pathways are complex and involve numerous different proteins termed clotting factors.
  5. 5. Extrinsic Pathway: Fibrin clot formation in response to tissue injury is the most clinically relevant event of homeostasis under normal physiological conditions. This process is the result of the activation of the extrinsic pathway. Intrinsic Pathway: The formation of a red thrombus or a clot in response to an abnormal vessel wall in the absence of tissue injury is the result of the intrinsic pathway.
  6. 6. Factors Pathway Activities XII Intrinsic Binds to exposed collagen at site of vessel wall injury. XI Intrinsic Activated by factor XIIa IX Intrinsic Activated by factor XIa in presence of Ca2+ X Both Activated on surface of activated platelets by tenase complex and by factor VIIa in presence of tissue factor and Ca2+. VII Extrinsic Activated by thrombin in presence of Ca2+. VIII Intrinsic Activated by thrombin; factor VIIIa is a cofactor in the activation of factor X by factor IXa. V Both Activated by thrombin; factor Va is a cofactor in the activation of prothrombin by factor Xa
  7. 7. Activation of Prothrombin to Thrombin The common point in both pathways is the activation of factor X to factor Xa. Factor Xa activates prothrombin (factor II) to thrombin (factor IIa). Thrombin, in turn, converts fibrinogen to fibrin. The activation of thrombin occurs on the surface of activated platelets and requires formation of a prothrombinase complex. This complex is composed of the platelet phospholipids, phosphatidylinositol and phosphatidylserine, Ca2+, factors Va and Xa, and prothrombin. Factor V is a cofactor in the formation of the prothrombinase complex, similar to the role of factor VIII in tenase complex formation. Like factor VIII activation, factor V is activated to factor Va by means of minute amounts and is inactivated by increased levels of thrombin. Factor Va binds to specific receptors on the surfaces of activated platelets and forms a complex with prothrombin and factor Xa.
  8. 8. Disorders Defects in the process of homeostasis, leading to bleeding disorders, have been identified at the level of the proteins of the clotting cascades, platelet activation and function, contact activation and antithrombin function. Hemophilia Disorders of Fibrinogen and Factor XIII vonWillebrand Disease (Deficiency of vWF results in defective platelet adhesion and causes a secondary deficiency in factor VIII, results are similar to Hemophilia) Antithrombin Deficiency (Antithrombin functions to inhibit several activated coagulation factors including thrombin, factor IXa and factor Xa, by forming a stable complex with the various factors.)

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