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level: VIDEO LEC (Extension of Level 1)

Questions and Answers List

level questions: VIDEO LEC (Extension of Level 1)

QuestionAnswer
3 stages of haemostasis:1. Vascular spasm - Damaged blood vessels will constrict to reduce blood flow to the damaged area. 2. Plate plug formation - Platelet bind to the walls of damaged vessels forming platelet plug and stopping bleeding. 3. Coagulation - Formation of a stable clot by converting fibrinogen to fibrin
The process of Coagulation involves series of proteins known as __ These circulate through the bloodstream as Zymogens and are activated upon (1) blood vessel damage or (2) tissue damageclotting factors
1 (Blood vessel damage) Damage to the endothelium of the blood vessels leads to the __ pathway 2 (Tissue damage) Trauma to extravascular cells will trigger the __ pathway.1 intrinsic 2 extrinsic
Intrinsic pathway process- The longer pathway and initiated by factor XII (a zymogen) into factor XIIa (an activated protease. Moreover, this is done upon the exposure to endothelial collagen. - Then factor XIIa will then activate factor XI to factor XIa. - Then factor XIa will then activate factor IX to factor IXa. - Then together with the factor IXa is the cofactor VIIIa which will activate factor X to factor Xa. - From there on, the common pathway begins.
Extrinsic pathway- Shorter and is initiated upon the release of Tissue factor, which is also known as factor III. It is released usually from tissue damage. - Tissue factor (factor III), will activate factor VII to factor VIIa. - Then factor VIIa in complex with factor III activates factor X to factor Xa. - From there on, the common pathway begins.
The conversion of factor X to factor Xa is done so by the complex named __“tenase”.
Tenase has two forms:1 Extrinsic: VIIa, III, and Ca2+ 2 Intrinsic: IXa, VIIIa (cofactor), phospholipid, and Ca2+
is also known as “Fibrin stabilizing factor”. It cross-links fibrin strands to form fibrin mesh. This is where the platelet blood stabilizes and complete coagulation.Factor XIII
Factor Xa PROCESS- It will then cleave the Prothrombin (II) to Thrombin (IIa) with the help of the cofactor, factor Va. - The thrombin in turn cleaves Fibrinogen (I) into Fibrin (Ia). - Thrombin also activates other factors in the intrinsic pathways such as factor XI and cofactors VIII, V, and factor XIII. - Factor XIII is also known as “Fibrin stabilizing factor”. It cross-links fibrin strands to form fibrin mesh. This is where the platelet blood stabilizes and complete coagulation.
Activated plates in Stages of Hemostasis:1 Secrete serotonin leading to Vascular spasm. 2 Become adhesive leading to platelet plug 3 Site for Coagulation
They prevent blood loss during wound healing but once the blood vessels are repaired, they must be dissolved to restore blood flow. This process is called Fibrinolysis.Blood clots
A small cascade that produces the enzyme plasmin which cleaves fibrin and dissolves the clot.Fibrinolysis
Vitamin K is important in the activation of factors __7, 9, 10, and 2
These two may or might lead to excessive bleeding.1 Liver disease (cirrhosis, hepatitis, cancer) 2 Vitamin-K deficiency
Drugs used to prevent thrombosis:1 Drugs that Inhibit platelet aggregation: a. Aspirin b. Clopidogrel c. Prasugrel 2 Drugs that inhibit coagulation: a. Heparin b. Warfarin