Factors Involved In Blood Coagulation
Write a short note on coagulation.
Answer. It is the spontaneous arrest of the bleeding.
Following are the factors which are involved in the mechanism of coagulation of blood:
- Factor I—Fibrinogen
- Factor II—Prothrombin
- Factor III—Thromboplastin (Tissue factor)
- Factor IV—Calcium ions
- Factor V—Labile factor
- Factor VI—Presence not approved
- Factor VII—Stable factor
- Factor VIII—Anti-hemophilic factor
- Factor IX—Christmas factor
- Factor X—Stuart-Prower factor
- Factor XI—Plasma thromboplastin antecedent
- Factor XII—Hageman factor
- Factor XIII—Fibrin-stabilizing factor
- Factor XIV—Prekallikrein
- Factor XV—Kallikrein
- Factor XVI—Platelet factor.
Coagulation Clotting Occurs In Three Stages
1. Formation of prothrombin activator.
2. Conversion of prothrombin into thrombin.
3. Conversion of firinogen to firin.
Formation of prothrombin activator: The prothrombin activator is formed in two ways:
Coagulation Extrinsic pathway
- Factor III initiates this pathway after injury to damage tissues.
After the injury, these tissues release thromboplastin which contains protein, phospholipid, and glycoprotein which act as proteolytic enzymes. - The glycoprotein and phospholipid component of thromboplastin converts factor X into activated factor X, in the presence of factor VIII.
- Activated factor X reacts with factor V and phospholipid content of tissue thromboplastin to form a prothrombin activator in the presence of calcium.
- Factor V is activated by thrombin formed from prothrombin. This factor V now accelerates the formation of the prothrombin activator.
Coagulation Intrinsic pathway: It occurs in the following sequence:
- During injury, the blood vessel is ruptured, the endothelium is damaged and collagen beneath the endothelium is exposed.
- When factor XII comes in contact with collagen, it is converted to active factor XII.
- The active factor XII converts inactive factor XI to active factor XI in the presence of kininogen.
- The activated factor XI activates factor IX in the presence of calcium ions.
- Activated factor IX activates factor X in the presence of factor VIII and calcium.
- When platelet comes in contact with the collagen of the damaged blood vessels, it releases phospholipids.
- Now, active factor X reacts with platelet phospholipid and factor V to form prothrombin activation in the presence of calcium ions.
- Factor V is activated by the positive feedback method.
Coagulation Conversion of prothrombin into thrombin: The Prothrombin activator converts prothrombin into thrombin in the presence of calcium by a positive feedback mechanism.
This accelerates the formation of extrinsic and intrinsic prothrombin activators.
Coagulation Conversion of fibrinogen to fibrin: During this, the soluble fibrinogen is converted to fibrin by thrombin.
The fibrinogen is converted to activated fibrinogen due to the loss of two pairs of polypeptides.
The first form of firing contains loosely arranged strands which are modified later into tight aggregate by factor XIII in the presence of calcium ions.
Leave a Reply