Mechanism Of Blood Coagulation

Normally, blood remains in the fluid form as longas it resides within its vessels. However, during blood coagulation it thickness and farms a gel called a clot or thrombus. it comprises a network of insoluble proteins fibers called fibrin in which the formed elements of blood are trapped. clotting occurs locally around the platelets plug and its capacity is to support and reinforce the platelet plug and cement blood that stays in the wound channel. the process of gel formation, called clotting or coagulation, is a progression of chemical reactions that culminates in the formation of fibrin threads. the excessive clotting of blood can block any blood vessels leading to the condition ,called thrombosis. on the other hand, if the blood takes too long to clot, it can cause hemorrhage.

Clotting include various substances known as clotting (coagulation)factors. these factors include calcium ions  Ca²⁺saveral inactive enzymes that are synthesized by hepatocytes (liver cells) and release into the bloodstream, and different molecules release by platelets or damage tissue.

The twelve clotting factors are identified by roman numerals 1 through XIII according to the order of their discovery. factor VI once believed to be a distinct clotting factor, is now thought to be identical to factor V.

I.   Fibrinogen (factor1)

II.  Prothrombin (factor2)

III. Thromboplastin (factor3)

IV.  Calcium (factor4)

V.   Proaccelerin or labile (factor5)

VI.  Stable factor (factor6)

VII. Christmas factor (factor9)

VIII. Stuart-power factor(factor10) 

IX.    Plasma thrombin antecedent (factor 11)

X.     Hagman factor (factor12)

XI.    Fibrin Stabilizing Factor (factor13)

Clotting is a complex cascade of enzymatic responses where each clotting factor activation numerous molecules in a fixed sequence and finally forms a large quantity of product (the insoluble protein fibrin). the entire mechanism takes quantity of product (the insoluble protein fibrin). the entire mechanism taken place through two pathways that lead to a common pathways as shown in 2.6: it can be divided into three stages:

1. Two pathways, called the extrinsic pathway, which will be described shortly, lead to the formation of prothrombin activator. once a prothrombin activator is formed, the subsequent steps are similar for both the extrinsic and intrinsic pathways. together, these two stages are referred to as the common pathway.

2. prothrombin activator converts prothrombin into the enzyme thrombin.

3. thrombin convert soluble fibrinogen into insoluble fibrin forms the threads of the clot.