Just Coag Flashcards
What is the primary role of primary hemostasis in the body’s response to vascular injury?
A) Formation of a stabilized clot with crosslinked fibrin
B) Initiation of coagulation factor activation
C) Immediate deposition of platelets at the injury site leading to plug formation
D) Activation of tissue plasminogen activator
Correct Answer: C
Rationale: Primary hemostasis is characterized by the immediate deposition of platelets at the endovascular injury site, leading to the formation of an initial platelet plug. This process is crucial for stopping bleeding in minor injuries but is insufficient alone for more significant damage where secondary hemostasis is needed.
Which component does NOT contribute to the anti-clotting effects of vascular endothelial cells?
A) Prostacyclin
B) Tissue Factor Pathway Inhibitor (TFPI)
C) Tissue factor
D) Adenosine diphosphatase
Correct Answer: C
Rationale: Vascular endothelial cells contribute to anti-clotting by producing several substances like prostacyclin, TFPI, and adenosine diphosphatase, which inhibit clot formation. Tissue factor, conversely, is involved in the activation of clotting and is a part of the extrinsic pathway of hemostasis.
During platelet activation, which substance is NOT released from the dense bodies within the platelets?
A) Calcium
B) Serotonin
C) Fibrinogen
D) ADP
Correct Answer: C
Rationale: Upon activation, platelets release the contents of their granules. Dense bodies specifically release substances like ADP, calcium, serotonin, and histamine. Fibrinogen, however, is contained within alpha granules, not dense bodies.
What is the composition of the complexes formed during each stage of the coagulation cascade?
A) Substrate, enzyme, and cofactor
B) Enzyme, cofactor, and calcium
C) Substrate, enzyme, cofactor, and calcium
D) Substrate, enzyme, and inhibitor
Correct Answer: C
Rationale: Each stage of the coagulation cascade involves the assembly of membrane-bound activation tenase-complexes composed of a substrate (inactive precursor), an enzyme (activated coagulation factor), a cofactor (accelerator or catalyst), and calcium. This combination is crucial for the progression of the cascade.
Which statement correctly describes the initiation and amplification roles of the intrinsic pathway in hemostasis?
A) It only activates in response to negatively charged substances and leads directly to fibrin clot formation.
B) It serves primarily to amplify thrombin generation initiated by the extrinsic pathway and involves several coagulation factors.
C) It is the primary pathway for initiating clotting after endothelial injury.
D) It functions independently of the extrinsic pathway to provide all necessary coagulants.
Correct Answer: B
Rationale: The intrinsic pathway was initially thought to occur only in response to endovascular contact with negatively-charged substances. Current understanding, however, places it as a secondary, amplification mechanism in hemostasis, primarily enhancing thrombin generation that was initiated by the extrinsic pathway.
Primary hemostasis is characterized by the formation of an initial platelet plug. This response is typically sufficient for what type of vascular injury?
A) Major surgical incisions
B) Severe trauma
C) Minor cuts or abrasions
D) Chronic ulcers
Correct Answer: C
Rationale: Primary hemostasis involves immediate platelet deposition at the site of an endovascular injury, leading to the formation of an initial platelet plug. This mechanism is primarily adequate for minor injuries such as cuts or abrasions.
What is a key characteristic of the clot formed during secondary hemostasis?
A) Reversible clot formation
B) Platelet aggregation only
C) Clot stabilization with crosslinked fibrin
D) Instant clot dissolution
Correct Answer: C
Rationale: Secondary hemostasis follows primary hemostasis and involves the activation of clotting factors that lead to the formation of a stabilized clot, secured with crosslinked fibrin. This ensures the clot is robust and durable.
Which enzyme is secreted by vascular endothelial cells to degrade adenosine diphosphate (ADP), a promoter of platelet activation?
A) Cyclooxygenase
B) Adenosine deaminase
C) Adenosine diphosphatase
D) Nitric oxide synthase
Correct Answer: C
Rationale: Vascular endothelial cells exhibit antithrombotic properties by secreting adenosine diphosphatase, which degrades ADP, thus preventing its role in further platelet activation.
Which of the following is NOT a phase of platelet alteration upon exposure to the extracellular matrix (ECM)?
A) Adhesion
B) Dissolution
C) Activation
D) Aggregation
Correct Answer: B
Rationale: Upon exposure to ECM, platelets undergo three key phases: adhesion, activation, and aggregation. Dissolution is not a phase of platelet alteration in this context.
Components of Coagulation Cascade Complexes
Each complex in the coagulation cascade consists of several components. Which of the following is NOT a part of these complexes?
A) A receptor
B) A substrate (inactive precursor)
C) An enzyme (activated coagulation factor)
D) Calcium
Correct Answer: A
Rationale: Each stage of the coagulation cascade requires the assembly of membrane-bound activation tenase-complexes composed of a substrate (inactive precursor), an enzyme (activated coagulation factor), a cofactor (accelerator or catalyst), and calcium. Receptors are not listed as components of these complexes.
Initially, the intrinsic pathway of coagulation was thought to be triggered only by contact with:
A) Collagen
B) Negatively-charged substances like glass or dextran
C) Platelet-derived growth factor
D) Tissue factor
Correct Answer: B
Rationale: The intrinsic pathway was once believed to be initiated solely by endovascular contact with negatively-charged substances such as glass or dextran. This view has evolved, recognizing its role as an amplification system in hemostasis.
Which type of granules within platelets contains ADP and calcium?
A) Alpha granules
B) Delta granules
C) Dense bodies
D) Lambda granules
Correct Answer: C
Rationale: Dense bodies within the platelets store several substances, including ADP and calcium, which are crucial for the activation and aggregation phases of platelet function.
Which components are necessary for converting factor X to Xa in the intrinsic pathway?
A) IXa, VIIIa, and platelet-membrane phospholipid
B) IXa, V, and endothelial cell phospholipid
C) VIIa and tissue factor
D) XIIa and prekallikrein
Correct Answer: A
Rationale: In the intrinsic pathway, the conversion of factor X to Xa requires the assembly of a complex involving factor IXa, VIIIa, platelet-membrane phospholipid, and calcium. This complex is crucial for propagating the clotting cascade towards thrombin generation.
Thrombin generation is amplified by the activation of which factors?
A) I, II, V, and X
B) V, VII, VIII, and IX
C) V, VII, VIII, and XI
D) II, VII, IX, and X
Correct Answer: C
Rationale: Activated thrombin (IIa) plays a pivotal role in hemostasis by activating factors V, VII, VIII, and XI. This process not only amplifies thrombin generation but also facilitates the propagation of the clotting cascade. Should also be 13
What is the primary role of the “prothrombinase complex” in the common pathway of coagulation?
A) Converts fibrinogen to fibrin
B) Converts prothrombin (II) to thrombin (IIa)
C) Activates platelets
D) Degrades clotting factors
Correct Answer: B
Rationale: The prothrombinase complex, formed by factor Xa and Va along with calcium on a phospholipid surface, rapidly converts prothrombin (II) into thrombin (IIa), which is a crucial step in the common pathway of coagulation.
Which statement accurately describes the function of thrombin in hemostasis?
A) Thrombin converts fibrinogen to fibrin monomers that polymerize to form the stable clot structure.
B) Thrombin directly activates platelets without any intermediates.
C) Thrombin degrades fibrinogen without polymerization.
D) Thrombin decreases platelet adhesion to damaged endothelial sites.
Correct Answer: A
Rationale: Thrombin cleaves fibrinopeptides A & B from fibrinogen, allowing the remaining fibrin monomers to polymerize and form a basic clot. This is a critical step in converting the soluble fibrinogen into an insoluble fibrin meshwork.
What is the role of factor XIIIa in the clotting process?
A) Initiates the conversion of prothrombin to thrombin.
B) Converts fibrinogen into fibrin monomers.
C) Crosslinks fibrin strands to stabilize and make an insoluble clot.
D) Activates platelets to release ADP and calcium.
Correct Answer: C
Rationale: Factor XIIIa is crucial for the stabilization phase of hemostasis, where it crosslinks the fibrin strands, significantly enhancing the durability and resistance of the clot to fibrinolytic degradation.
Which complexes are responsible for the formation of prothrombinase in the coagulation cascade?
A) Intrinsic and extrinsic tenase complexes
B) Prothrombinase and fibrinogenase complexes
C) Tissue factor and von Willebrand factor complexes
D) Factor VIII and von Willebrand factor complexes
Correct Answer: A
Rationale: Both intrinsic and extrinsic tenase complexes facilitate the formation of the prothrombinase complex, which is pivotal for converting prothrombin to thrombin, advancing the clotting process in the common pathway.
Tissue Factor Pathway Inhibitor (TFPI)
How does TFPI contribute to anticoagulation?
A) It inhibits thrombin directly.
B) It forms a complex with factor Xa that inhibits the TF/VIIa complex, downregulating the extrinsic pathway.
C) It converts plasminogen to plasmin.
D) It activates factor VIII and factor IX.
Correct Answer: B
Rationale: Tissue Factor Pathway Inhibitor (TFPI) significantly contributes to anticoagulation by forming a complex with factor Xa, which then inhibits the tissue factor/factor VIIa complex, thus downregulating the extrinsic pathway of coagulation.
What critical role does von Willebrand factor (vWF) play in platelet function?
A) Converts fibrinogen to fibrin
B) Breaks down clots
C) Enhances platelet adhesion and prevents degradation of factor VIII
D) Activates prothrombin to thrombin
Correct Answer: C
Rationale: von Willebrand factor is essential for normal blood clotting as it plays a critical role in platelet adhesion and aggregation, and stabilizes factor VIII by protecting it from rapid degradation in the circulation.
Which of the following statements best describes the effect of chronic liver disease on hemostasis?
A) Patients with chronic liver disease only show reduced levels of pro-coagulation factors with normal levels of anticoagulation factors.
B) Chronic liver disease results in prolonged PT and PTT due to impaired synthesis and clearance of coagulation factors.
C) Chronic liver disease exclusively causes qualitative platelet dysfunction without affecting coagulation factors.
D) In chronic liver disease, there is increased clearance of clotting factors leading to bleeding.
Correct Answer: B
Rationale: Chronic liver disease affects hemostasis through multifactorial pathways including impaired synthesis of coagulation factors, platelet dysfunction, and impaired clearance of clotting and fibrinolytic proteins, typically showing prolonged PT and possibly PTT.
What is commonly used to treat platelet dysfunction in chronic renal disease (CKD) patients?
A) Oral anticoagulants
B) Cryoprecipitate and DDAVP
C) Vitamin K antagonists
D) Thrombolytic therapy
Correct Answer: B
Rationale: Treatment of platelet dysfunction in CKD patients involves using agents such as cryoprecipitate (rich in von Willebrand factor) and DDAVP (desmopressin), which can help stabilize clotting and address uremic platelet dysfunction
What laboratory findings are characteristic of disseminated intravascular coagulation (DIC)?
A) Elevated platelet count and shortened PT
B) Decreased fibrinogen levels and normal platelet count
C) Decreased platelets, prolonged PT/PTT, increased fibrin degradation products
D) Normal thrombin time and decreased D-dimer levels
Correct Answer: C
Rationale: DIC is characterized by consumption of platelets and coagulation factors due to widespread thrombosis, typically showing decreased platelets, prolonged PT/PTT, and elevated levels of fibrin degradation products, indicative of enhanced fibrinolytic activity.
What mechanism is primarily involved in trauma-induced coagulopathy?
A) Direct inhibition of thrombin by externally administered anticoagulants
B) Genetic predisposition to bleeding disorders
C) Activated protein C mediated decrease in thrombin generation
D) Excessive production of vitamin K-dependent coagulation factors
Correct Answer: C
Rationale: Trauma-induced coagulopathy often involves activated protein C, which decreases thrombin generation. This mechanism can be triggered by the body’s response to trauma and is thought to contribute to the coagulopathy observed in these patients.
