Intrinsic and extrinsic coagulation pathways pdf

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intrinsic and extrinsic coagulation pathways pdf

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Thrombin generation TG is a pivotal process in achieving hemostasis.

Intrinsic pathway of blood coagulation

Platelets are key players in hemostasis , the process by which the body seals a ruptured blood vessel and prevents further loss of blood. Although rupture of larger vessels usually requires medical intervention, hemostasis is quite effective in dealing with small, simple wounds. There are three steps to the process: vascular spasm, the formation of a platelet plug, and coagulation blood clotting. Failure of any of these steps will result in hemorrhage —excessive bleeding. When a vessel is severed or punctured, or when the wall of a vessel is damaged, vascular spasm occurs. In vascular spasm , the smooth muscle in the walls of the vessel contracts dramatically.

Coagulation is the process by which a blood clot forms to reduce blood loss after damage to a blood vessel. Several components of the coagulation cascade, including both cellular e. The role of the cellular and protein components can be categorized as primary hemostasis the platelet plug and secondary hemostasis the coagulation cascade. The coagulation cascade is classically divided into three pathways: the contact also known as the intrinsic pathway, the tissue factor also known as the extrinsic pathway , and the common pathway. Both the contact pathway and the tissue factor feed into and activate the common pathway.

Negreva, K. Vitlianova, R. Background: Clinical interest in the haemostasis profile of patients with paroxysmal atrial fibrillation PAF , and in particular, in blood coagulation is significant. It is known that blood coagulation is activated in two pathways: extrinsic and intrinsic. Regardless of the activation method, the coagulation cascade ends with a final common pathway, in which the activated factor X FX is central to the prothrombin complex, responsible for the conversion of prothrombin factor II F II to thrombin that converts fibrinogen into fibrin.

The extrinsic pathway of blood coagulation

The article also illustrates the appropriateness of monitoring treatment in specialist units to maintain the level of anticoagulation within the very narrow margin that allows prevention of thrombosis without causing bleeding complications. All thrombotic processes have their origin in the dysfunction or rupture of the vascular endothelium, leading to release of tissue factor, which initiates the process of coagulation, and of collagen and von Willebrand factor, which initiates adhesion and activation of platelets. Alteration of the homeostatic balance between prothrombotic and antithrombotic factors during anticoagulation therapy can result in insufficient inhibition of coagulation thrombosis or the occurrence of bleeding due to excessive antithrombotic treatment. The interpretation of the coagulation process described by MacFarlane 2 in the "MacFarlane cascade" has been of use for many years in beginning to understand the complex problem of thrombus formation. Both pathways converge to activate factor X and lead to transformation of prothrombin into thrombin and, through the action of thrombin, of fibrinogen into fibrin.


Secondary hemostasis includes the two main coagulation pathways, intrinsic and extrinsic, that meet up at a point to form the common pathway.


A mathematical model for in vitro coagulation of blood: role of platelet count and inhibition

Upon the introduction of cells, particularly crushed or injured tissue, blood coagulation is activated and a fibrin clot is rapidly formed. The protein on the surface of cells that is responsible for the initiation of blood clotting is known as tissue factor , or tissue thromboplastin. Tissue factor is found in many of the cells of the body but is particularly abundant in those of the brain, lungs, and placenta. The pathway of blood coagulation activated by tissue factor, a protein extrinsic to blood, is known as the extrinsic pathway Figure 1.

All the components necessary for the clotting process to proceed are found in the blood. As such, the proteins required for such clotting to take place are part of the intrinsic pathway of blood coagulation. This pathway involves a series of proteins, protein cofactors, and enzymes, which interact in reactions that take place on membrane surfaces. These reactions are initiated by tissue injury and result in the formation of a fibrin clot Figure 1.

Natalya M. Ananyeva, Diana V. Kouiavskaia, Midori Shima, Evgueni L. Saenko; Intrinsic pathway of blood coagulation contributes to thrombogenicity of atherosclerotic plaque.

Blood coagulation refers to the process of forming a clot to stop bleeding. Coagulation is a complicated subject and is greatly simplified here for the student's understanding. To stop bleeding, the body relies on the interaction of three processes: Primary hemostasis involves the first two processes.

16.5D: Coagulation

A mechanistic model including the role of platelets is proposed for clot formation and growth in plasma in vitro. Initiation of clot formation is by the addition of tissue factor, and initiation via the intrinsic pathway is neglected. Activation of zymogens follows the extrinsic pathway cascade and reactions on platelet membranes are included. Platelet activation occurs due to thrombin and also due to other activated platelets. The model predictions matched existing data for thrombin production in synthetic plasma.

Но Пьер Клушар провалился в глубокое забытье. ГЛАВА 23 Сьюзан, сидя в одиночестве в уютном помещении Третьего узла, пила травяной чай с лимоном и ждала результатов запуска Следопыта. Как старшему криптографу ей полагался терминал с самым лучшим обзором. Он был установлен на задней стороне компьютерного кольца и обращен в сторону шифровалки. Со своего места Сьюзан могла видеть всю комнату, а также сквозь стекло одностороннего обзора ТРАНСТЕКСТ, возвышавшийся в самом центре шифровалки.

 - Это очень важно. Клушар заморгал. - Я не знаю… эта женщина… он называл ее… - Он прикрыл глаза и застонал. - Как. - Не могу вспомнить… - Клушар явно терял последние силы.


This study aimed to evaluate the extrinsic and intrinsic pathways of coagulation, serum level of fibrinogen and platelet count in HIV positive patients and.


Key Points

Тридцать лет отдал он служению своей стране. Этот день должен был стать днем его славы, его piece de resistance, итогом всей его жизни - днем открытия черного хода во всемирный стандарт криптографии. А вместо этого он заразил вирусом главный банк данных Агентства национальной безопасности. И этот вирус уже невозможно остановить - разве что вырубить электроэнергию и тем самым стереть миллиарды бит ценнейшей информации. Спасти ситуацию может только кольцо, и если Дэвид до сих пор его не нашел… - Мы должны выключить ТРАНСТЕКСТ! - Сьюзан решила взять дело в свои руки.  - Я спущусь вниз, в подсобное помещение, и выключу рубильник. Стратмор медленно повернулся.

ГЛАВА 62 Коммандер и Сьюзан стояли у закрытого люка и обсуждали, что делать. - Итак, внизу у нас погибший Чатрукьян, - констатировал Стратмор.  - Если мы вызовем помощь, шифровалка превратится в цирк. - Так что же вы предлагаете? - спросила Сьюзан. Она хотела только одного - поскорее уйти. Стратмор на минуту задумался.

Когда он проходил мимо лифта, дверцы открылись. В кабине стоял какой-то мужчина.

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