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Questions and Answers

What is the main function of hemostasis?

Hemostasis is the process that stops bleeding and prevents blood loss from the body.

What are the two main stages of hemostasis?

  • Internal and External
  • Active and Passive
  • Fast and Slow
  • Primary and Secondary (correct)

    • Primary hemostasis is responsible for the stabilization of the platelet plug.

    False

    What is the function of the coagulation cascade in hemostasis?

    <p>The coagulation cascade generates thrombin, which converts fibrinogen into fibrin, ultimately forming a stable fibrin clot that reinforces the platelet plug.</p> Signup and view all the answers

    Which of the following is NOT a factor involved in the extrinsic pathway of coagulation?

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

    What is the role of calcium ions (Ca2+) in the coagulation cascade?

    <p>Calcium ions act as cofactors for many of the clotting factors, facilitating their activation and interaction, ultimately contributing to the formation of a stable fibrin clot.</p> Signup and view all the answers

    What is the clinical blood test that measures the overall function of the extrinsic pathway?

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

    What is the difference between the intrinsic and extrinsic pathways of the coagulation cascade?

    <p>The extrinsic pathway is triggered by the exposure of tissue factor (TF) and is initiated by the activation of factor VII, while the intrinsic pathway is triggered by the activation of factor XII on contact with exposed collagen.</p> Signup and view all the answers

    The common pathway of the coagulation cascade is triggered by the activation of Factor Xa.

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

    Match the following coagulation tests with their corresponding pathways:

    <p>Prothrombin Time (PT) = Extrinsic pathway and Common pathway Activated Partial Thromboplastin Time (aPTT) = Intrinsic pathway and Common pathway Bleeding Time = Primary Hemostasis</p> Signup and view all the answers

    What is the primary cause of disorders of primary hemostasis?

    <p>Disorders of primary hemostasis are primarily due to abnormalities in platelets, which can be either quantitative or qualitative disorders.</p> Signup and view all the answers

    Which of the following is a clinical feature of disorders of primary hemostasis?

    <p>Mucosal and Skin Bleeding</p> Signup and view all the answers

    What is the most common overall symptom of mucosal bleeding in disorders of primary hemostasis?

    <p>Epistaxis, or nosebleed, is the most common overall symptom of mucosal bleeding in disorders of primary hemostasis.</p> Signup and view all the answers

    What is the most common cause of thrombocytopenia in children and adults?

    <p>Immune thrombocytopenic purpura (ITP) is the most common cause of thrombocytopenia in children and adults.</p> Signup and view all the answers

    In disorders of primary hemostasis, both the PT and PTT tests are usually abnormal.

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

    What is the primary cause of disorders of secondary hemostasis?

    <p>Disorders of secondary hemostasis are primarily caused by factor abnormalities, which can be due to various factors such as genetic deficiencies, liver disease, autoantibodies, or vitamin K deficiency.</p> Signup and view all the answers

    Which of the following is a clinical feature of disorders of secondary hemostasis?

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

    Hemophilia A is a hereditary bleeding disorder caused by a deficiency in factor IX.

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

    What is von Willebrand disease?

    <p>Von Willebrand disease is a lifelong bleeding disorder characterized by low levels of von Willebrand factor (vWF), a protein that helps platelets adhere to the damaged blood vessel.</p> Signup and view all the answers

    In von Willebrand disease, the PT test is usually abnormal.

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

    What is the significance of the coagulation tests in evaluating bleeding disorders?

    <p>Coagulation tests, including PT, aPTT, and bleeding time, help diagnose and monitor bleeding disorders by assessing different components of the hemostasis process, including platelet function and the coagulation cascade.</p> Signup and view all the answers

    Hemostasis is the process of stopping ______.

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

    Primary hemostasis involves the coagulation cascade.

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

    What is the main function of the coagulation cascade?

    <p>To form a fibrin clot</p> Signup and view all the answers

    What are the three main steps of secondary clotting?

    <p>Secondary clotting occurs in three main steps: formation of prothrombinase, conversion of prothrombin to thrombin, and conversion of fibrinogen to fibrin.</p> Signup and view all the answers

    The intrinsic pathway of coagulation is triggered by the activation of Factor VII.

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

    Which of the following blood tests is used to evaluate the overall function of the intrinsic pathway?

    <p>Activated Partial Thromboplastin Time (aPTT)</p> Signup and view all the answers

    What are the three main requirements for the activation of clotting factors?

    <p>The activation of clotting factors requires exposure to an activating substance like tissue thromboplastin, the presence of a phospholipid surface (found on platelets), and calcium ions.</p> Signup and view all the answers

    The extrinsic pathway is longer and more complex than the intrinsic pathway.

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

    What is the most common cause of disorders of secondary hemostasis?

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

    Hemophilia B is characterized by a deficiency in Factor VIII.

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

    What is the role of von Willebrand factor (vWF) in hemostasis?

    <p>vWF plays a crucial role in platelet adhesion to the damaged blood vessel and also helps stabilize Factor VIII, which is essential for the coagulation cascade.</p> Signup and view all the answers

    Von Willebrand disease is a genetic disorder that affects the coagulation cascade of blood clotting.

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

    What is the overall purpose of the coagulation tests?

    <p>Coagulation tests are essential for diagnosing and monitoring bleeding disorders by assessing various components of the hemostasis process, including platelet function and the coagulation cascade, helping to determine the underlying cause of bleeding and guide treatment options.</p> Signup and view all the answers

    Study Notes

    Blood Coagulation Tests

    • Coagulation tests assess the blood's ability to clot (PT, PTT, BT)
    • Hemostasis is the body's natural response to stop bleeding from an injured vessel.
    • It involves a complex series of steps that lead to the formation of a blood clot.

    What is Hemostasis?

    • The integrity of blood vessels is crucial for proper blood transport to tissues.
    • Hemostasis repairs injuries by forming a thrombus (blood clot) at the site of injury to prevent and stop blood loss.
    • The term is derived from "hemo" (blood) and "stasis" (standing still).
    • Blood vessel damage triggers hemostasis, which stops bleeding.

    Hemostasis Stages

    • Hemostasis occurs in two phases: primary and secondary.
    • Primary hemostasis involves platelet activation and plug formation to control bleeding.
      • Vasoconstriction
      • Platelet adhesion
      • Platelet activation
      • Platelet aggregation/Platelet plug
    • Secondary hemostasis involves the formation of a stable fibrin clot, solidifying the platelet plug.
      • The coagulation cascade which activates clotting factors following activation of clotting factors in blood plasma (extrinsic and intrinsic pathway, common pathway).

    Hemostasis: Blood Clotting

    • Serum is blood plasma minus its clotting proteins.
    • Clotting (coagulation) factors are made by hepatocytes (liver cells), released into the bloodstream in an inactive form.
    • Secondary hemostasis clotting is a series of steps culminating in the formation of insoluble fibrin threads from fibrinogen, forming a blood clot. This includes the extrinsic, intrinsic, and common pathways.
    • Blood clotting prevents extensive bleeding when blood vessels are harmed.

    Coagulation Tests (PT, PTT, and BT)

    • Bleeding time (BT) assesses the primary hemostasis (platelets phase)
    • Prothrombin time (PT) measures the extrinsic and common pathways function.
    • Activated partial thromboplastin time (aPTT) measures the intrinsic and common pathways function.

    Secondary Hemostasis

    • Coagulation consists of the extrinsic, intrinsic, and common pathways. These pathways operate individually but converge.
    • Extrinsic pathway starts with tissue damage and the release of tissue thromboplastin, activating Factor VII.
    • Intrinsic pathway begins when exposed collagen activates Factor XII.
    • Both pathways converge into the common pathway, which involves factors X, V, II (Prothrombin), I (Fibrinogen), and XIII.
    • The final product is a stable fibrin clot.

    Disorders of Primary Hemostasis

    • Clinical signs include mucosal bleeding, hematuria, epistaxis, menorrhagia, and skin bleeds (petechiae, purpura, ecchymoses).
    • Laboratory tests include platelet count and bleeding time.
    • Disorders can be quantitative (low platelet count) or qualitative (platelets fail to function as expected). Examples include immune thrombocytopenic purpura (ITP)

    Disorders of Secondary Hemostasis

    • Clinical manifestations include deep tissue and joint bleeding, and re-bleeding after surgery.
    • Laboratory evaluations include prothrombin time and activated partial thromboplastin time.
    • Factor abnormalities (e.g., hemophilia A, hemophilia B, von Willebrand disease) are common causes.

    Hemophilia A

    • Factor VIII deficiency.
    • Elevated aPTT, normal PT, normal platelet count, and bleeding time.

    Hemophilia B

    • Factor IX deficiency.
    • Elevated aPTT, normal PT, normal platelet count, and bleeding time.

    von Willebrand Disease

    • Deficiency of von Willebrand factor (vWF).
    • Prolonged bleeding time, normal PT, and increased aPTT.

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