Platelet Physiology & Coagulation Fundamentals - Answer Key

MEDICAL LABORATORY SCIENCE 8. SUMMATIVE EXAM REVIEW QUESTIONS #11 + ANSWERS & RATIONALIZATIONS 1. 2. 3. 4. 5. 6. 7. The growth factor that is produced in the kidney/liver and induces growth and differentiation of committed megakaryocyte progenitors is: a. IL-3 b. IL-6 c. IL-11 d. TPO Which of the following is (are) true of endoreduplicaiton? a. Duplicates DNA without cell division b. Results in cells with ploidy values of 4n, 8n, 16n and 32n c. Is unique to the megakaryocytic type of blood cell d. All of the above → Endoreduplication or endomitosis ▪ Megakaryocyte maturation is marked by a mysterious form of mitosis that lacks telophase and cytokinesis (separation into daughter cells) and is called endomitosis. The megakaryocyte progenitor that undergoes endomitosis is: a. MK-I b. BFU-Meg c. CFU-Meg d. LD-CFU-Meg The cellular ultrastructural component unique to the platelet is the: a. Cytoplasmic membrane b. Glycocalyx c. Mitochondrion d. Microtubule Which of the following is not a characteristic of platelets? a. The presence of a nucleus b. Size of 2 to 4 µm c. Cytoplasm is light blue with fine red-purple granules d. A discoid shape as an inactive cell Choose the INCORRECT STATEMENT regarding storage granules related to hemostasis in the mature platelet. a. Alpha granules contain platelet factor 4, betathromboglobulin, and platelet-derived growth factor. b. Alpha granules contain platelet fibrinogen and von Willebrand factor. c. Dense bodies contain serotonin and ADP. d. Lysosomes contain actomyosin, myosin, and flamin → Lysosomes, the third type of granule store hydrolase enzymes. Platelet aggregation will occur with the end production of: a. Cyclooxygenase b. Arachidonic acid c. Prostacyclin d. Thromboxane A2 9. 10. 11. 12. 13. 14. 15. 16. 17. Reticulated platelets can be enumerated in peripheral blood to detect: a. Impaired production in disease states b. Abnormal organelles associated with diseases such as leukemia c. Increased platelet production in response to need d. Inadequate rates of membrane cholesterol exchange with the plasma At all times, approximately ___ of the total number of platelets are in the systemic circulation. a. One-fourth b. One-third c. One-half d. Two-thirds The reference range of platelets in the systemic circulation is: a. 50 to 120 x 109/L b. 100 to 200 x 109/L c. 150 to 350 x 109/L d. 150 to 400 x 109/L Agents that are capable of aggregating platelets include: a. Collagen b. Thrombin c. Serotonin d. All of the above In measuring platelet aggregation, platelet-rich plasma can be treated with ______ to aggregate platelets. a. Saline b. Collagen c. Epinephrine d. Both B and C What coagulation plasma protein should be assayed when platelets fail to aggregate properly? a. Factor VIII b. Fibrinogen c. Thrombin d. Factor X Aspirin ingestion has the following hemostatic effect in a normal person. a. Prolongs the bleeding time b. Prolongs the clotting time c. Inhibits factor VIII d. Has no effect The bleeding time test measures: a. Ability of platelets to stick together b. Platelet adhesion and aggregation of locally injured vascular subendothelium c. Quantity and quality of platelets d. Antibodies against platelets The clot retraction test is: a. Visible reaction to the activation of platelet actomyosin (thrombosthenin) b. Reflection of the quantity and quality of platelets and other factors c. Measurement of the ability of platelets to stick to glass d. Measurement of the cloudiness of blood Wiskott-Aldrich syndrome is characterized by: a. Giant platelets b. Smallest platelets seen c. Large platelets d. Absence of platelets 1 18. May-Hegglin anomaly is characterized by: a. Giant platelets b. Smallest platelets seen c. Large platelets d. Absence of platelets 19. Bernard-Soulier syndrome is characterized by: a. Giant platelets b. Smallest platelets seen c. Large platelets d. Absence of platelets 20. Hereditary platelet dysfunction can be caused by: a. Aspirin b. von Willebrand’s disease c. Uremia d. Factor V deficiency 21. Which of the following parameters can be abnormal in classic von Willebrand’s disease type I? a. Bleeding time b. PT c. Platelet count d. All of the above 22. The most common form of von Willebrand’s disease is: a. Type I b. Type II c. Type III → most severe d. All have about the same incidence 23. When comparing von Willebrand’s disease and Glanzmann’s thrombasthenia, Glanzmann’s thrombasthenia will demonstrate: a. Absent ADP b. Normal clot retraction c. Abnormal ristocetin aggregation d. Abnormal release of ADP 24. Acquired platelet dysfunction can be caused by: a. Aspirin b. Von Willebrand’s disease c. Uremia d. Factor V deficiency 25. Thrombin: a. III b. XII c. VIII d. IIa 26. Tissue thromboplastin: a. III b. XII c. VIII d. IIa 27. Anti-hemophilic factor: a. III b. XII c. VIII d. IIa 28. Hageman factor: a. III b. XII c. VIII d. IIa 29. The extrinsic pathway of coagulation is triggered by the entry of _______ into the circulation. a. Membrane lipoproteins (phospholipoproteins) b. Tissue thromboplastin c. Calcium d. Factor VII 30. The intrinsic pathway of coagulation begins with the activation of ______ in the early stage. a. Factor II b. Factor I c. Factor XII d. Factor V 31. The final common pathway of the intrinsic-extrinsic pathway is: a. Factor X activation b. Factor II activation c. Factor I activation d. Factor XII activation 32. Fibrinogen is converted to fibrin monomers by: a. Prothrombin b. Thrombin c. Calcium ions d. Factor XIIIa 33. The fibrinogen group of coagulation factors: a. Known to increase during pregnancy b. Known to increase in conditions of inflammation c. Known to increase subsequent to the use of oral contraceptives d. All of the above 34. A pregnant woman has routine coagulation testing performed. PT and APTT are normal. Her fibrinogen level is elevated at 450 (reference range 150 to 350) due to acute phase reactants during pregnancy. The other factor that may be elevated due to this is: a. FVII b. FVIII c. FXI d. FXIII 35. Vitamin K dependent coagulation factor: a. II b. V c. VIII d. XIII 36. Unique characteristic associated with associated with a deficiency of Factor XII is: a. Frequent nose bleeds b. No history of bleeding c. Common factor deficiency d. Decreased risk of forming blood clots 37. Factor XII deficiency is associated with: a. Bleeding episodes b. Epistaxis c. Decreased risk of thrombosis d. Increased risk of thrombosis 38. What happens if a coagulation specimen collection tube is underfilled? a. The specimen clots and is useless b. The specimen is hemolyzed and is useless c. Clot-based test results are falsely prolonged d. Chromogenic test results are falsely decreased 2 39. Most coagulation testing must be performed on PPP, which is plasma with a platelet count less than: a. 1000/µL b. 10,000/µL c. 100,000/µL d. 1,000,000/µL 40. The function of thromboplastin in the prothrombin test is to provide ______ to the assay. a. Kaolin b. Fibrinogen c. Phospholipoprotein d. Thrombin 41. An abnormally prolonged APTT may indicate: a. Severe depletion of fibrinogen b. Presence of circulating anticoagulant c. Factor VIII deficiency d. All of the above 42. Neither the APTT nor the PT detects a deficiency of: a. Platelet factor 3 b. Factor VII c. Factor VIII d. Factor IX 43. Which laboratory test is affected by heparin therapy? a. Thrombin time b. Fibrinogen assay c. Protein C assay d. Protein S assay 44. The test reagent in APTT contains which of the following substance(s)? • Citrated plasma • Calcium ions • Tissue thromboplastin • Phospholipids 47. A patient on therapeutic warfarin will most likely have a(n): a. Normal PT/INR, increased APTT, prolonged bleeding time, low platelet count b. Increased PT/INR, increased APTT, normal bleeding time, normal platelet count c. Normal PT/INR, normal APTT, normal bleeding time, normal platelet count d. Increased PT/INR, normal APTT, prolonged bleeding time, low platelet count → Warfarin - vitamin K antagonist which inhibits FII, FVII, FIX, FX 48. If heparin therapy is initiated in a patient, a decreased anticoagulant response can be caused by decreased levels of: a. Platelet factor 3 b. Platelet factor 4 c. Anti-thrombin d. Factor XIII 49. Heparin-induced thrombocytopenia (HIT) results from: a. Antibodies to heparin b. Antibodies to platelets c. Antibodies to PF4 d. Antibodies to heparin-PF4 complex 50. A modification of which procedure can be used to measure fibrinogen? a. PT b. APTT c. Thrombin time d. Fibrin degradation products a. 1, 2 and 3 are correct b. 1 and 3 are correct c. 2 and 4 are correct d. Only 4 is correct 45. The test reagent in PT contains which of the following substance(s)? • Calcium ions • Kaolin • Tissue thromboplastin • Celite a. 1, 2 and 3 are correct b. 1 and 3 are correct c. 2 and 4 are correct d. Only 4 is correct 46. If a child ingested rat poison, which of the following tests should be performed to test the effect of the poison on the child’s coagulation mechanism? a. aPTT b. PT c. Fibrinogen assay d. Thrombin time 3