HEMA 2 LEC MIDTERM EXAM
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What is the primary concern when collecting specimens for secondary hemostasis testing?

  • Preventing premature activation of the clotting process (correct)
  • Preventing factor VII depletion
  • Preventing excessive bleeding
  • Preventing platelet activation

    • What is released from injured cells, activating the extrinsic pathway?

  • Tissue factor (correct)
  • Factor XI
  • Platelet activator
  • Factor VIII

    • Why should glass containers be avoided when collecting specimens for hemostasis testing?

  • Glass is too expensive
  • Glass is too heavy for transport
  • Glass is non-sterile
  • Glass provides a negatively charged surface, activating the intrinsic pathway (correct)

    • Why are polystyrene tubes preferred over glass tubes for hemostasis testing?

    <p>Polystyrene tubes do not activate the intrinsic pathway</p> Signup and view all the answers

    What is the consequence of prolonged tourniquet application during blood collection?

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

    What is the primary pathway activated when there is endothelial damage?

    <p>Extrinsic pathway</p> Signup and view all the answers

    What factors are labile at room temperature?

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

    What is the consequence of using glass containers for hemostasis testing?

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

    What is the effect of improper temperature on factor VII?

    <p>It is prematurely activated</p> Signup and view all the answers

    Why should tourniquet application be minimized during blood collection?

    <p>To prevent hemolysis</p> Signup and view all the answers

    Which of the following coagulopathies is most commonly encountered?

    <p>Hemophilia A</p> Signup and view all the answers

    Which factor is complexed with von Willebrand factor?

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

    What is the pattern of abnormal coagulation tests in factor VII deficiency?

    <p>Abnormal PT, normal APTT</p> Signup and view all the answers

    What is the term for a complete absence of fibrinogen?

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

    Which of the following is an autosomal defect?

    <p>Hemophilia C</p> Signup and view all the answers

    What is the term for a decrease in fibrinogen levels?

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

    In which ethnic group is factor XI deficiency most commonly seen?

    <p>Ashkenazi Jews</p> Signup and view all the answers

    What is the primary inhibitor of thrombin that is deficient in a specific hemorrhagic disorder?

    <p>Antithrombin-III</p> Signup and view all the answers

    Which of the following is NOT a deficiency that leads to thrombosis?

    <p>Factor IX Deficiency</p> Signup and view all the answers

    What is the name of the syndrome characterized by Factor XI Deficiency?

    <p>Rosenthal Syndrome</p> Signup and view all the answers

    What is the characteristic of Factor VIII Deficiency?

    <p>Sex-linked</p> Signup and view all the answers

    Which of the following is associated with thrombosis due to prostacyclin inhibition?

    <p>Lupus anticoagulant</p> Signup and view all the answers

    What is the characteristic of Factor IX Deficiency?

    <p>Sex-linked</p> Signup and view all the answers

    Which of the following is a secondary hemorrhagic disorder?

    <p>Post-operative states</p> Signup and view all the answers

    Which fibrin degradation product is a powerful inhibitor of thrombin?

    <p>Fragment E</p> Signup and view all the answers

    What is the characteristic of primary fibrinolysis?

    <p>No D-dimer formation</p> Signup and view all the answers

    What is the consequence of excessive plasminogen activator from damaged cells or malignant cells?

    <p>Primary fibrinolysis</p> Signup and view all the answers

    What is the primary purpose of fibrinolysis?

    <p>To keep the vascular system free of deposited fibrin and fibrin clots</p> Signup and view all the answers

    What is the result of plasminogen conversion to plasmin?

    <p>Dissolution of fibrin or fibrinogen into smaller fragments</p> Signup and view all the answers

    Which of the following is an example of secondary fibrinolysis?

    <p>Disseminated intravascular coagulation (DIC)</p> Signup and view all the answers

    What is the function of plasmin?

    <p>To systematically digest fibrin polymer</p> Signup and view all the answers

    What is the function of fragment X and Y?

    <p>Exert anticoagulant effects</p> Signup and view all the answers

    What can activate plasminogen to plasmin?

    <p>Factor XIa, kallikrein, HMWK, and a specific plasma protein</p> Signup and view all the answers

    What is the composition of D-dimer?

    <p>Two D domains from separate fibrin molecules</p> Signup and view all the answers

    What is the characteristic of secondary fibrinolysis?

    <p>Presence of fibrin monomer and D-dimer</p> Signup and view all the answers

    What are the fragments produced by the degradation of fibrin or fibrinogen by plasmin?

    <p>FDP, FSP, X, Y, D, and E</p> Signup and view all the answers

    What is the first and largest fragment produced by the degradation of fibrin or fibrinogen by plasmin?

    <p>Fragment X</p> Signup and view all the answers

    Which of the following is a plasminogen activator?

    <p>Tissue type urokinase</p> Signup and view all the answers

    What is the consequence of excessive plasminogen activator from damaged cells or malignant cells on fibrinogen levels?

    <p>Decrease in fibrinogen levels</p> Signup and view all the answers

    What is the result of the cleavage of fragment X by plasmin?

    <p>Formation of an intermediate complex DED and fragment Y</p> Signup and view all the answers

    What is the end result of the degradation of fibrin or fibrinogen by plasmin?

    <p>Formation of FDP and FSP</p> Signup and view all the answers

    What is the function of plasminogen activators?

    <p>To convert plasminogen to plasmin</p> Signup and view all the answers

    What happens to whole blood collected in a glass tube without anticoagulant?

    <p>It clots spontaneously</p> Signup and view all the answers

    What is the purpose of the Euglobulin Lysis Time test?

    <p>To measure fibrinolysis</p> Signup and view all the answers

    What is the reference range for the Euglobulin Lysis Time test?

    <p>Lysis in less than 2 hours</p> Signup and view all the answers

    What is the principle of the Protamine Sulfate Gelation Test?

    <p>Protamine sulfate replaces secondary degradation products from fibrin monomers and primary FDPs</p> Signup and view all the answers

    What is the reference range for the Protamine Sulfate Gelation Test?

    <p>No gel formation is seen</p> Signup and view all the answers

    What is the principle of the Ethanol Gelation Test?

    <p>50% ethanol causes soluble fibrin monomer to dissociate</p> Signup and view all the answers

    What is the reference range for the Ethanol Gelation Test?

    <p>No gel formation is seen</p> Signup and view all the answers

    What is the purpose of the Latex D-Dimer Assay?

    <p>To measure a specific fragment arising from degradation</p> Signup and view all the answers

    What is the characteristic of the Whole Blood Clot Lysis Time test?

    <p>Clot should remain intact for 48 hours</p> Signup and view all the answers

    What is the role of epinephrine and serotonin in the coagulation process?

    <p>They promote vasoconstriction</p> Signup and view all the answers

    What is the mechanism by which platelets adhere to the site of vascular injury?

    <p>Through the binding of large soluble macromolecules to distinct glycoprotein receptors</p> Signup and view all the answers

    What is the result of the internal contraction of platelets during the coagulation process?

    <p>The release of granular contents from alpha and dense granules</p> Signup and view all the answers

    What is the function of functional glycoprotein IIb/IIIa receptors on the surface of platelets?

    <p>To mediate platelet aggregation through fibrinogen bridges</p> Signup and view all the answers

    What is the initial step in the coagulation process following vascular injury?

    <p>The adhesion of platelets to subendothelial collagen</p> Signup and view all the answers

    What is the primary function of platelet adhesion to the subendothelial collagen fibers?

    <p>To maintain vascular integrity</p> Signup and view all the answers

    Which of the following agonists can lead to platelet activation?

    <p>Thromboxane A2</p> Signup and view all the answers

    What is the result of platelet activation and aggregation at sites of vascular damage?

    <p>Release of molecules involved in hemostasis and wound healing</p> Signup and view all the answers

    What is the function of platelet-derived growth factor released during vascular healing?

    <p>To stimulate the migration of endothelial cells</p> Signup and view all the answers

    What is the initial response of platelets to vascular injury?

    <p>Adhesion to subendothelial collagen fibers</p> Signup and view all the answers

    What is the immediate response to vascular injury?

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

    What process involves the precipitation of polymerized fibrin around each platelet?

    <p>Consolidation of platelets</p> Signup and view all the answers

    What is the normal range of platelets per 100× (oil) immersion field in a properly prepared blood smear?

    <p>8 to 20</p> Signup and view all the answers

    What is the purpose of examining the peripheral blood smear for platelet number and morphology?

    <p>To assess platelet quantity and morphology for clinical clues</p> Signup and view all the answers

    What is the result of the consolidation of platelets and fibrin stabilization?

    <p>Irreversible platelet plug</p> Signup and view all the answers

    What is the role of fibrinogen in platelet aggregation?

    <p>It forms a sticky surface on platelets</p> Signup and view all the answers

    What is the effect of aspirin on platelet function?

    <p>It induces a long-lasting functional defect in platelets</p> Signup and view all the answers

    What can initiate platelet aggregation?

    <p>Particulate material, proteolytic enzymes, and biological amines</p> Signup and view all the answers

    What is the result of platelet aggregation reinforced by fibrin?

    <p>A thrombus forms</p> Signup and view all the answers

    What substances can block platelet aggregation by at least one pathway?

    <p>Prostaglandin E, adenosine, and nonsteroidal anti-inflammatory agents</p> Signup and view all the answers

    What is the effect of aspirin on thromboxane A2 synthesis, in relation to platelet function?

    <p>It inhibits its synthesis</p> Signup and view all the answers

    What is the consequence of a platelet count below 100 × 10^9/L on bleeding time?

    <p>Bleeding time increases progressively</p> Signup and view all the answers

    What is the primary mechanism of clot retraction?

    <p>Platelet contraction</p> Signup and view all the answers

    What is the duration of the effect of aspirin on platelet function?

    <p>The duration of the life span of the platelet</p> Signup and view all the answers

    What is the significance of a prolonged bleeding time in a patient with a normal platelet count?

    <p>Impaired platelet function or a defect of subendothelial factor</p> Signup and view all the answers

    What is the primary ligand that binds to functional glycoprotein IIb/IIIa receptors?

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

    What is the approximate number of glycoprotein IIb/IIIa receptors per platelet?

    <p>50,000</p> Signup and view all the answers

    What is the peptide recognition sequence that mediates binding with expressed glycoprotein IIb/IIIa receptors?

    <p>Arginine-glycine-aspartic acid</p> Signup and view all the answers

    What is the primary mechanism of platelet recruitment?

    <p>Glycoprotein IIb/IIIa-dependent platelet cohesion</p> Signup and view all the answers

    What is the location where the intrinsic coagulation reactions occur?

    <p>Platelet surface phospholipids</p> Signup and view all the answers

    What is the purpose of using aspirin and clopidogrel in patients undergoing a stent procedure?

    <p>To prevent subacute stent thrombosis</p> Signup and view all the answers

    What is the role of ADP in platelet aggregation assays?

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

    What is the principle of the turbidimetric aggregometer used in platelet aggregation assays?

    <p>It measures the change in light transmission as platelets aggregate</p> Signup and view all the answers

    What is the characteristic of the curve elicited by epinephrine in platelet aggregation assays?

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

    What is the purpose of the ristocetin cofactor assay?

    <p>To measure vWF activity</p> Signup and view all the answers

    What is the role of arachidonic acid in platelet aggregation assays?

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

    What is the effect of platelet aggregation on blood flow?

    <p>It decreases blood flow</p> Signup and view all the answers

    What is the purpose of lumiaggregation in platelet aggregation assays?

    <p>To extend the aggregation assay</p> Signup and view all the answers

    What is the role of collagen in platelet aggregation assays?

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

    What is the consequence of abnormal platelet aggregation?

    <p>Subacute stent thrombosis</p> Signup and view all the answers

    Study Notes

    Hemostasis and Thrombosis

    • Hemostasis: a process that prevents excessive bleeding when a blood vessel is injured
    • Thrombosis: a process that forms a blood clot (thrombus) inside a blood vessel

    Factors Affecting Blood Coagulation

    • Tissue thromboplastin (tissue factor): released from injured cells, activates the extrinsic pathway
    • Glass containers: activate the intrinsic pathway, attract platelets, and should be replaced with polystyrene or silicone-coated tubes
    • Improper temperature: affects labile factors (V, VIII, XI), and premature activation
    • Hemolysis: caused by prolonged tourniquet application, can affect blood coagulation tests

    Intrinsic Pathway Disorders

    • Factor XI deficiency (Hemophilia C): mild bleeding, autosomal, more than half of cases in Ashkenazi Jews
    • Factor VIII: C deficiency (Hemophilia A): sex-linked, factor VIII:C complexed with vWF
    • Factor IX deficiency (Hemophilia B): sex-linked, Christmas disease

    Extrinsic and Common Pathway Disorders

    • Factor VII deficiency: abnormal PT, normal APTT and thrombin time
    • Factor X (Stuart-Prower factor) deficiency: abnormal APTT and PT, normal TCT
    • Factor V deficiency (Owen's disease): abnormal APTT and PT, normal TCT
    • Factor II (prothrombin) deficiency: abnormal APTT and PT, normal TCT
    • Factor I deficiency: abnormal APTT, PT, and TCT

    Fibrinolysis

    • Primary purpose: to digest fibrin clots as they are formed to keep the vascular system free of deposited fibrin and fibrin clots
    • Occurs when plasminogen is converted to plasmin, which dissolves fibrin or fibrinogen into FDP (fibrin degradation products) or FSP (fibrin split products)

    Tests for Fibrinolysis

    • Whole blood clot lysis time: measures excessive systemic fibrinolysis
    • Euglobulin lysis time: a more rapid and sensitive assay of lytic activity
    • Protamine sulfate gelation test: a test for secondary (smaller) fibrin degradation products
    • Ethanol gelation test: less sensitive but more specific than protamine sulfate test in detecting soluble fibrin monomers and polymers in plasma
    • Latex D-dimer assay: measures a specific fragment arising from degradation of fibrin

    Platelet Adhesion and Aggregation

    • Platelet adhesion: mediated by the binding of large soluble macromolecules to distinct glycoprotein receptors anchored in the platelet membrane
    • Platelet aggregation: the sticking or clumping of platelets to each other
    • Platelet plug formation: the result of platelet adhesion and aggregation
    • Platelet cohesion: mediated by functional glycoprotein IIb/IIIa receptors for circulating adhesive ligand proteins (primarily fibrinogen)

    Laboratory Assessment of Platelets

    • Platelet count: a fundamental component in the evaluation of a patient
    • Platelet aggregation: the gold standard test to determine platelet function
    • Platelet aggregation assays: use various platelet activators to identify abnormal platelet function and to monitor antiplatelet drug therapy

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    Related Documents

    Week 8: Tests for Secondary Hemostasis PDF
    Week 9 PDF - Hemorrhagic Disorders
    Fibrinolysis PDF
    Week 11 Tests for Fibrinolysis PDF
    Clinical Hematology - Turgeon PDF

    Description

    This quiz covers the importance of proper specimen collection in hemostasis testing to prevent premature activation of the clotting process. Learn about the causes of activation, including tissue thromboplastin and inappropriate container use.

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