The research of coagulation

The definition of coagulation

Coagulation, refers to the flow of liquid from the state of the flow of gel state can not flow of the process, is an important part of physiological hemostasis. The essence of blood clotting is the process in which soluble fibrinogen in plasma becomes insoluble fibrin.

The basic introduction of coagulation

Blood clotting refers to the process of blood from the state of the liquid into a gel state can not flow, is an important part of physiological hemostasis.

In the role of the prothrombin activator, plasma inactive factor II (prothrombin) is activated as a factor of activity Ⅱ a, (thrombin).

In the role of thrombin, soluble in plasma fibrinogen into fibrin monomer; at the same time, thrombin activation XIII for XIIIa, so that fibrin monomers are linked to each other to form insoluble fibrin polymer, and Interwoven into a net, the blood cells included, the formation of blood clots, complete the blood clotting process.

Blood coagulation is a series of enzymatic biochemical reaction process, there are many positive feedback effect, once the start will be carried out rapidly in order to ensure a shorter period of time there coagulation hemostatic effect.

The process of coagulation

The basic process of coagulation is a series of limited proteolytic processes of proteins, generally divided into three stages:

1, prothrombin activator formation

2, thrombin formation

3, fibrin formation

Coagulation related to introduction

Prothrombin activator Xa, V, Ca²+ and PF3 (platelet factor 3, the platelet membrane phospholipid) complex, its formation requires the activation of factor x first. According to the formation of prothrombin activator pathway and the participation of different factors, can be divided into endogenous coagulation coagulation and clotting two ways.

Endogenous coagulation

All factors involved in clotting are plasma.

Blood contacts the negatively charged foreign body surface, coagulation factor 12 binds to the foreign body surface and is activated, activated coagulation factor 12 will activate coagulation factor 11 and further promote the activation of coagulation factor 12, binding from the coagulation factor 12 to the foreign body surface To the activation of coagulation factor 11 production process into a surface activation, the process also need to be as a cofactor to stimulate macromolecule kininogen.

Activated coagulation factor 11 activates factor 9 in the presence of calcium ions, and activated factor-9 binds to the membrane-bound phospholipid provided by the activated platelet-activated factor-10 enzyme complex under the action of calcium ions. The complex Activated coagulation factor 10, activated coagulation factor 10 in the presence of calcium ions and activated coagulation factor 5 in the phospholipid membrane surface formation of prothrombin complex, prothrombin complex activation of prothrombin, thrombin activation of coagulation factor 13 And fibrinogen, coagulation factor 13 to promote the formation of soluble fibrinogen insoluble polyfibrin multimer, thus forming a blood clot to stop bleeding.

Exogenous coagulation

The initiation factor is the tissue factor from the tissue, so this pathway is also called the tissue factor pathway.

Tissue factor is a glycoprotein, present in the cell membrane of most tissue cells. When the tissue injury, tissue factor exposure, the blood of activated coagulation factor 7 (about 0.5% of the total blood clotting factor) and tissue factor binding complex, the complex in the presence of phospholipids and calcium ions in the case of rapid Activated coagulation factor 10, activated coagulation factor 10 in the presence of calcium ions and activated coagulation factor 5 in the phospholipid membrane surface formation of prothrombin complex, prothrombin complex activates prothrombin, thrombin activation of coagulation factor 13 and Fibrinogen, coagulation factor 13 to promote the formation of soluble fibrinogen insoluble polyfibrin multimer, thus forming a blood clot to stop bleeding.

The difference between the two approaches

The differences between endogenous coagulation and extrinsic coagulation are:

Endogenous coagulation is completely dependent on intravascular coagulation factors, so that the activation of the process of factor 10 involved more enzymes, slower coagulation process. Exogenous coagulation depends on extravascular release of factor III, the activation of factor X, the number of enzymes involved in less rapid coagulation.

In addition to clotting factors 3, 4, 5 and a portion of factor 13, the other coagulation factors are synthesized by the liver.

Some people because of genetic defects, leading to some important factor in the synthesis of clotting disorders, resulting in coagulation disorders, leading to prolonged blood clotting, the disease is hemophilia.

The coagulation process requires a variety of factors often associated with, for example, fibrinogen, platelets, and vitamin K.

Thrombin formation

Prothrombin  is a 582 amino acid residues of the zymogen, by factor Xa at Arg-Thr and Arg-Ile incision, excision of N-terminal 274 amino acid residues, the remaining 308 amino acid residues into A, B two peptide chain, connected by a disulfide bond, which is thrombin (thrombin). Factor Va without enzyme activity, but can enhance the activity of Xa 350 times to accelerate thrombin generation. Phospholipid particles and enzyme (Xa) and substrate (prothrombin) by Ca + + as a bridge connected. Because prothrombin peptide chain N? -terminal contains 10 gamma carboxyglutamic acid residues. The adjacent carboxyl groups may form a complex with Ca ++.

Fibrin formation

In the role of thrombin, soluble in plasma fibrinogen into fibrin monomer; at the same time, thrombin activation XIII for XIIIa, so that fibrin monomers are linked to each other to form insoluble fibrin polymer, and Interwoven into a net, the blood cells included, the formation of blood clots, complete the blood clotting process.

Blood coagulation is a series of enzymatic biochemical reaction process, there are many positive feedback effect, once the start will be carried out rapidly in order to ensure a shorter period of time there coagulation hemostatic effect.