W1-12 Blood clotting
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Questions and Answers

What is the role of platelets in blood clotting?

  • Promote vasoconstriction
  • Form a plug at the site of vessel damage (correct)
  • Inhibit the fibrinolytic system
  • Regulate the vitamin K cycle

    • Which event occurs first when a blood vessel is damaged?

  • Platelet plug formation
  • Coagulation cascade
  • Vasoconstriction (correct)
  • Activation of the fibrinolytic system

    • What is the main function of the fibrinolytic system?

  • Inhibit coagulation cascade
  • Promote platelet aggregation
  • Stimulate vasoconstriction
  • Break down fibrin to dissolve blood clots (correct)

    • What is the process by which the vessel wall regulates hemostasis and thrombosis?

    <p>Endothelial cell activation</p> Signup and view all the answers

    Which vitamin is involved in blood coagulation and its regulation?

    <p>Vitamin K</p> Signup and view all the answers

    What is the purpose of vasoconstriction in the process of hemostasis?

    <p>To minimize blood loss from damaged vessels</p> Signup and view all the answers

    What is the primary function of tissue factor pathway inhibitor 1 (TFPI-1) in the clotting cascade?

    <p>Inhibiting factor Xa</p> Signup and view all the answers

    What happens as soon as a small amount of factor Xa is produced?

    <p>The extrinsic pathway is turned off</p> Signup and view all the answers

    In the absence of von Willebrand factor (VWF), what happens to the half-life of factor VIII?

    <p>Shortens</p> Signup and view all the answers

    Which factor has a key role in binding to collagen and releasing factor VIII when damage occurs to blood vessels?

    <p>Von Willebrand factor (VWF)</p> Signup and view all the answers

    What does thromboxane A2 (TXA2) do in the blood clotting process?

    <p>Increases platelet activation and aggregation</p> Signup and view all the answers

    What is the purpose of thromboplastin in the blood clotting process?

    <p>Combining with tissue factor III to activate the extrinsic pathway</p> Signup and view all the answers

    Which factors are directly involved in forming fibrin polymer?

    <p>Factors XIII and I</p> Signup and view all the answers

    What is the function of plasminogen activators in the blood clot dissolution process?

    <p>Convert plasminogen to active plasmin</p> Signup and view all the answers

    What is the primary function of Activated Thrombomodulin in the blood clotting process?

    <p>Inactivating Factor Va and VIIIa</p> Signup and view all the answers

    Which substance inhibits the synthesis of thromboxane A2?

    <p>Aspirin</p> Signup and view all the answers

    What is the primary function of Antithrombin III in the coagulation process?

    <p>Inactivating thrombin and other coagulation factors</p> Signup and view all the answers

    Which of the following is true about thrombus and embolus?

    <p>A thrombus forms in a broken vessel, while an embolus forms in an unbroken vessel.</p> Signup and view all the answers

    Which factor deficiency causes hemophilia A?

    <p>Factor VIII</p> Signup and view all the answers

    What is the function of prostacyclin (PGI2) in hemostasis?

    <p>It inhibits platelet aggregation</p> Signup and view all the answers

    What activates the extrinsic pathway of the coagulation cascade?

    <p>External trauma causing blood to escape from the vascular system</p> Signup and view all the answers

    In what way is partial thromboplastin different from thromboplastin?

    <p>Partial thromboplastin contains tissue factor III, while thromboplastin does not.</p> Signup and view all the answers

    What is the main role of thromboxane A2 in hemostasis?

    <p>Amplification of platelet activation and recruitment of additional platelets to the site of injury</p> Signup and view all the answers

    Which condition is a result of the complete occlusion of one or more coronary arteries?

    <p>Myocardial infarction</p> Signup and view all the answers

    What is the function of tissue factor in the coagulation cascade?

    <p>Activation of the extrinsic pathway</p> Signup and view all the answers

    What activates the intrinsic pathway of the coagulation cascade?

    <p>Trauma inside the vascular system</p> Signup and view all the answers

    What is a characteristic of deep vein thrombosis (DVT)?

    <p>It can occur in the lower leg, thigh, or pelvis.</p> Signup and view all the answers

    What are some symptoms of hemophilia?

    <p>Prolonged bleeding even from minor injuries</p> Signup and view all the answers

    What activates platelets to adhere to exposed subendothelium during hemostasis?

    <p>von Willebrand factor (vWF)</p> Signup and view all the answers

    What is the primary function of thrombomodulin in the blood clotting process?

    <p>Activating protein C and inhibiting procoagulant functions of thrombin</p> Signup and view all the answers

    Which test is used to detect lupus anticoagulants and factor VIII inhibitors?

    <p>Kaolin Clotting Time (KCT)</p> Signup and view all the answers

    What is the normal range for International Normalized Ratio (INR) used to monitor individuals on warfarin therapy?

    <p>2.0-3.0</p> Signup and view all the answers

    What does a longer thrombin time indicate?

    <p>All of the above</p> Signup and view all the answers

    Which condition is caused by another disease or condition that makes the body's normal blood clotting process become overactive?

    <p>Disseminated Intravascular Coagulation (DIC)</p> Signup and view all the answers

    What causes prolonged bleeding and coagulation time in the absence of vitamin K?

    <p>Insufficient dietary intake of vitamin K</p> Signup and view all the answers

    What is the end result of the coagulation cascade?

    <p>Activation of thrombin</p> Signup and view all the answers

    What is the primary function of proteins C and S in hemostasis?

    <p>Proteolysis of Va and VIIIa</p> Signup and view all the answers

    What is the main function of antithrombin in hemostasis?

    <p>Inactivation of thrombin</p> Signup and view all the answers

    Which substance synthesized by the endothelium inhibits platelet aggregation and release of platelet granules?

    <p>Prostacyclin (PGI2)</p> Signup and view all the answers

    In hemostasis, what is the end result of the activation of thrombin?

    <p>Fibrin formation</p> Signup and view all the answers

    What is the effect of endothelium-derived vasoconstrictors such as endothelin in hemostasis?

    <p>Localized vasoconstriction</p> Signup and view all the answers

    Which laboratory test should the physician use to monitor heparin therapy?

    <p>Activated partial thromboplastin time (aPTT)</p> Signup and view all the answers

    The patient started to experience adverse effects to heparin therapy. Which drug should be used to reverse the action of heparin?

    <p>Protamine sulfate</p> Signup and view all the answers

    How would an increased consumption of green leafy vegetables be expected to alter the patient’s International Normalized Ratio (INR)?

    <p>It would be decreased.</p> Signup and view all the answers

    Which of the following most accurately describes the mechanism of action of clopidogrel?

    <p>The active metabolite of clopidogrel binds to and inhibits the platelet ADP receptors</p> Signup and view all the answers

    Which one of the following drugs was used to manage the man with a myocardial infarction?

    <p>Alteplase</p> Signup and view all the answers

    What is the primary function of heparin in the blood clotting process?

    <p>Inhibiting thrombin activity</p> Signup and view all the answers

    In what way does warfarin exert its anticoagulant effect?

    <p>Inhibiting vitamin K epoxide reductase</p> Signup and view all the answers

    What is the key pharmacological target of aspirin in reducing platelet aggregation?

    <p>Cyclooxygenase-1 (COX-1)</p> Signup and view all the answers

    What is the primary function of desmopressin in managing bleeding disorders?

    <p>Increasing von Willebrand factor release</p> Signup and view all the answers

    Which of the following is NOT an adverse effect of low molecular weight heparin (LMWH)?

    <p>Heparin induced thrombocytopenia (HIT)</p> Signup and view all the answers

    What is the antidote for dabigatran in case of severe bleeding?

    <p>Monoclonal antibody, idarucizumab</p> Signup and view all the answers

    What is the primary route of excretion for warfarin metabolites?

    <p>Urine</p> Signup and view all the answers

    Which drug is recommended as an alternative to heparin in patients with or at risk of heparin-induced thrombocytopenia?

    <p>Bivalirudin</p> Signup and view all the answers

    What is the mechanism of action for rivaroxaban?

    <p>Binds to factor Xa</p> Signup and view all the answers

    What is the pharmacological effect of alteplase?

    <p>Breaks down fibrin (lyse clots)</p> Signup and view all the answers

    Which factor deficiency accounts for most of the heritable coagulation defects?

    <p>Factor VIII deficiency</p> Signup and view all the answers

    What is used to treat hemophilia and von Willebrand disease by increasing factor VIII activity?

    <p>Desmopressin</p> Signup and view all the answers

    Which condition is a contraindication for the use of alteplase?

    <p>Active internal bleeding or hemorrhagic disorder</p> Signup and view all the answers

    Which medication binds to antithrombin and was likely given to the patient for managing pulmonary embolism?

    <p>Low molecular weight heparin (LMWH)</p> Signup and view all the answers

    What are the primary adverse effects associated with direct thrombin inhibitors?

    <p>Gastrointestinal adverse effects and bleeding</p> Signup and view all the answers

    What is the primary route of administration for warfarin?

    <p>Oral</p> Signup and view all the answers

    Which enzyme does aspirin inhibit to reduce platelet-mediated production of thromboxane A2?

    <p>Cyclooxygenase (COX-1)</p> Signup and view all the answers

    What is the main target for clopidogrel in inhibiting platelet aggregation?

    <p>ADP P2Y12 receptors</p> Signup and view all the answers

    What is the mechanism of action of abciximab in preventing platelet aggregation?

    <p>Binds non-competitively to glycoprotein IIb/IIIa receptors</p> Signup and view all the answers

    What is the main pharmacokinetic route of elimination for low molecular weight heparins (LMWH)?

    <p>Urine</p> Signup and view all the answers

    What does tissue factor pathway inhibitor (TFPI) limit the action of?

    <p>Tissue factor (TF)</p> Signup and view all the answers

    What is the therapeutic use of abciximab?

    <p>Prevention of acute cardiac ischemic complications</p> Signup and view all the answers

    What is the main function of high molecular weight fractions of heparin?

    <p>Inhibit IIa, IXa, Xa</p> Signup and view all the answers

    What is the mechanism of action of eptifibatide and tirofiban in preventing platelet aggregation?

    <p>Competitive antagonists of glycoprotein IIb/IIIa receptors</p> Signup and view all the answers

    Study Notes

    • Blood clotting is the process of sealing a damaged blood vessel (hemostasis).
    • Occurs in three stages: vasoconstriction, platelet plug formation, and coagulation of blood.
    • Hemostasis takes place within 3-6 minutes after injury.
    • Platelets rush to the injury site and form a plug using insoluble fibrin.
    • Thromboplastin activates the extrinsic pathway of coagulation.
    • There are two types of thromboplastin: tissue factor (TF) and partial thromboplastin.
    • TF combines with phospholipids and tissue factor III to activate the extrinsic pathway.
    • Hemostatic disorders include thrombus and embolus formation, leading to conditions like coronary thrombosis and myocardial infarction.
    • Factors causing thrombus include injury to the blood vessel or build-up of fatty plaques.
    • Hemophilia is a genetic disorder caused by missing or defective clotting factors.
    • Hemophilia A and Hemophilia B are caused by deficiency in Factor VIII and Factor IX, respectively.
    • Hemophilia C, or plasma thromboplastin antecedent (PTA) deficiency, is a rare condition caused by missing or defective Factor XI.
    • Endothelial cells line blood vessels and prevent inappropriate clotting, while the subendothelium is thrombogenic.
    • Platelets adhere to exposed subendothelium and form a plug through the action of thrombin and platelet-derived mediators.
    • Prostacyclin is a potent vasodilator and endogenous inhibitor of platelet aggregation.
    • Arachidonic acid is synthesized by platelets and leads to the formation of thromboxane A2, a lipid mediator that amplifies platelet activation.
    • Both the intrinsic and extrinsic pathways are essential for efficient blood clotting in the body.
    • Factor VIII functions as a co-factor in the blood coagulation cascade.
    • Tissue factor pathway inhibitor (TFPI) inhibits Factor Xa and the FVIIa-tissue factor complex.
    • Factor VIII is carried by von Willebrand factor (VWF) in circulation, releasing it upon injury to function as a co-factor in the blood coagulation cascade.

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    Description

    This quiz covers the intertwined nature of the intrinsic and extrinsic clotting pathways in the body, and how their collaboration is essential for efficient clot formation. It delves into the clotting cascade triggered by tissue factor exposure and the significance of each pathway's steps.

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