Drugs in Coagulation Disorders (PHRC-5832)
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Questions and Answers

What is the primary role of the vascular phase in hemostasis?

  • Breakdown of the clot after vessel repair
  • Reduction of blood flow through vasoconstriction (correct)
  • Aggregation of platelets to form a plug
  • Formation of a fibrin clot
  • Which substance released from endothelial cells contributes to vasoconstriction during hemostasis?

  • Fibrin
  • Endothelin (correct)
  • Thromboxane A2
  • Serotonin
  • In which phase does platelet aggregation occur to form a plug?

  • Fibrinolytic phase
  • Coagulation phase
  • Platelet phase (correct)
  • Vascular phase
  • What is the significance of collagen exposure during the hemostatic process?

    <p>It facilitates adhesion of platelets to the damaged area.</p> Signup and view all the answers

    What is one of the key actions of thromboxane A2 during hemostasis?

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

    Which of the following best describes the coagulation phase in hemostasis?

    <p>Activation of clotting factors to form a fibrin clot</p> Signup and view all the answers

    What occurs during the fibrinolytic phase of hemostasis?

    <p>The clot is broken down after vessel repair.</p> Signup and view all the answers

    Which of the following correctly represents the sequence of phases in normal hemostasis?

    <p>Vascular phase → Platelet phase → Coagulation phase → Fibrinolytic phase</p> Signup and view all the answers

    What initiates the intrinsic pathway of coagulation?

    <p>Exposure of clotting factors to negatively charged surfaces</p> Signup and view all the answers

    Which of the following factors is responsible for activating factor XI in the intrinsic pathway?

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

    What role does thrombin play in the coagulation process?

    <p>Converts fibrinogen into fibrin</p> Signup and view all the answers

    Which component is involved in the positive feedback loop during coagulation?

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

    What is activated by factor XIII once thrombin acts upon it?

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

    What initiates the common pathway in coagulation?

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

    Which elements are required for the activation of factor X in the common pathway?

    <p>Factor V, calcium ions, platelet membrane phospholipids</p> Signup and view all the answers

    What is the final structural component formed from fibrinogen during coagulation?

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

    What component is primarily responsible for stabilizing the blood clot?

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

    What is a 'thrombin burst'?

    <p>Rapid generation of thrombin from thrombin</p> Signup and view all the answers

    What is the role of thromboxane A2 in the platelet activation process?

    <p>It enhances platelet activation.</p> Signup and view all the answers

    Which receptor on platelets is responsible for binding to collagen?

    <p>GP Ia / GPVI receptor</p> Signup and view all the answers

    What substance is released by platelets that activates the coagulation cascade?

    <p>Adenosine diphosphate (ADP)</p> Signup and view all the answers

    What is the main role of Nitric Oxide (NO) in hemostasis?

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

    Which of the following is NOT a factor dependent on hemostasis?

    <p>High Levels of Oxygen</p> Signup and view all the answers

    Which process involves the temporary formation of a platelet plug at a site of vascular injury?

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

    What is the primary component of the mesh that traps cells and reinforces the platelet plug?

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

    What prevents thrombin from diffusing to surrounding areas during hemostasis?

    <p>Adsorption to fibrin</p> Signup and view all the answers

    What effect does the release of serotonin have during the activation of platelets?

    <p>Enhances platelet activation.</p> Signup and view all the answers

    What is a defining characteristic of a pulmonary embolism?

    <p>A clot that floats within the blood in the lungs</p> Signup and view all the answers

    Which structure in blood vessels do platelets primarily adhere to during the platelet phase?

    <p>Subendothelial matrix</p> Signup and view all the answers

    Which anticoagulant is released from mast cells to inactivate thrombin?

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

    What does the fibrinolytic system do during hemostasis?

    <p>Activates plasminogen to form plasmin</p> Signup and view all the answers

    What mechanism triggers the release of granules containing ADP and serotonin from platelets?

    <p>Collagen activation</p> Signup and view all the answers

    What primarily forms a white clot in the circulatory system?

    <p>Aggregated platelets in arterial blood</p> Signup and view all the answers

    Which substance plays a crucial role in preventing platelet adherence to uninjured endothelial cells?

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

    What is the primary composition of a red clot?

    <p>Fibrin strands with trapped blood cells</p> Signup and view all the answers

    Which class of drugs is primarily used to treat red clots?

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

    Which of the following is a direct thrombin inhibitor?

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

    Deep vein thrombosis (DVT) is often associated with which of the following factors?

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

    What is the primary action of thrombolytics?

    <p>Lyse thrombi</p> Signup and view all the answers

    Which anticoagulant is an indirect thrombin inhibitor?

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

    Which of the following is NOT an antifibrinolytic agent?

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

    What type of antiplatelet drug is Ticagrelor?

    <p>PAR-1 inhibitor</p> Signup and view all the answers

    Study Notes

    Hemostasis and Coagulation Overview

    • Hemostasis prevents or stops bleeding through a complex process involving clotting factors.
    • Phases of hemostasis:
      • Vascular phase: Vasospasm reduces blood flow.
      • Platelet phase: Platelet aggregation forms a plug.
      • Coagulation phase: Fibrin clot formation occurs.
      • Fibrinolytic phase: Breakdown of the clot post-repair.

    Vascular Phase

    • Injury to blood vessels triggers vasoconstriction to decrease blood flow, aided by:
      • Endothelin released from endothelial cells.
      • Thromboxane A2 and serotonin from activated platelets enhance vasoconstriction.

    Platelet Phase

    • Steps in platelet adhesion and activation:
      • Damage exposes collagen in the vessel wall.
      • Platelets adhere to collagen, morph into a spiky shape, and release substances like ADP and thromboxane A2.
      • Platelet aggregation is crucial for clot formation.

    Coagulation Cascade

    • Intrinsic pathway activated by vascular damage and negatively charged subendothelial surfaces.
      • Contributions of factors: XII, XI, IX, and VIII lead to activation of factor X.
    • Common pathway involves:
      • Factor Xa converting prothrombin into thrombin.
      • Thrombin transforms fibrinogen into fibrin to form the clot structure.

    Major Components of Hemostasis

    • Stable hemostasis relies on:
      • Integrity of the vessel wall.
      • Adequate platelet counts and function.
      • Sufficient levels of clotting factors and fibrinolytic activity.

    Pathological Thrombus Formation

    • Thrombus: Fixed clot on a vessel wall; embolus: Free-floating clot.
    • Risks include obstruction of blood vessels, leading to conditions like pulmonary embolism.
    • Anticoagulants help prevent thrombus formation.

    Types of Blood Clots

    • White clots (arterial) consist mainly of platelets; red clots (venous) consist largely of fibrin and trapped blood cells.
    • Treatment differs by clot type: antiplatelet agents for white clots and anticoagulants for red clots.

    Anticoagulant Classification

    • Anticoagulants reduce blood coagulability, divided into:
      • Indirect thrombin inhibitors (e.g., heparins).
      • Direct thrombin inhibitors (e.g., hirudin).
    • Antiplatelet agents interfere with platelet function; notable examples include aspirin and clopidogrel.
    • Thrombolytics dissolve existing clots.

    Common Anticoagulant Drugs

    • Parenteral options include unfractionated heparin and low molecular weight heparins (e.g., enoxaparin).
    • Oral options include Warfarin and direct oral anticoagulants (e.g., rivaroxaban, apixaban).

    Reversal Agents for Oral Anticoagulants

    • Idarucizumab for direct thrombin inhibitors.
    • Andexanet alfa for factor Xa inhibitors.

    Antiplatelet Classification Mechanisms

    • Varying action mechanisms including GP receptor inhibitors (e.g., Abciximab, Eptifibatide) and specific receptor antagonists (e.g., Vorapaxar).

    Thrombolytics and Antifibrinolytic Agents

    • Thrombolytic agents like streptokinase and tissue plasminogen activator promote clot lysis.
    • Antifibrinolytics such as aminocaproic acid help prevent clot breakdown.

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    Description

    This quiz covers the mechanisms of coagulation and hemostasis, focusing on major classes of antiplatelet and anticoagulant medications. You will explore their mechanisms of action along with associated toxicities and drug interactions. Test your knowledge of pharmacology in these critical areas.

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