Coagulation Cascade and HMWK Overview
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Coagulation Cascade and HMWK Overview

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Questions and Answers

What process activates complement in the given context?

  • Cleavage of C3 (correct)
  • Protein synthesis
  • Mitosis
  • Phagocytosis

    • C3a acts as a potent anaphylotoxin causing increased vascular permeability.

    True

    What function does C3b serve in the immune response?

    Opsonization

    Human High Molecular Weight Kininogen (HMWK) has a molecular weight of ______ daltons.

    <p>120,000</p> Signup and view all the answers

    Which serine protease is NOT mentioned as being implicated in clinical disorders?

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

    Antithrombin is a serine protease inhibitor involved in thrombin inhibition.

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

    During reperfusion, complement may be activated by exposure to ______ components.

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

    Match the complement components to their functions:

    <p>C3a = Increased vascular permeability C3b = Opsonization HMWK = Cofactor for FXI activation Antithrombin = Thrombin inhibition</p> Signup and view all the answers

    Which of the following components is NOT part of the complement system?

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

    Activated complement fragments can damage self-tissues.

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

    What is the primary role of activated complement fragments?

    <p>To bind and damage self-tissues.</p> Signup and view all the answers

    Cells express regulators of complement activation to protect against __________.

    <p>deleterious effects of cell-bound complement fragments</p> Signup and view all the answers

    What is the normal range for activated partial thromboplastin time (APTT)?

    <p>Less than 35 seconds</p> Signup and view all the answers

    Anticoagulants are expected to increase the inflammatory response.

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

    Name one of the major natural anticoagulant mechanisms.

    <p>Antithrombin.</p> Signup and view all the answers

    The __________ is the test of choice for screening deficiencies of factors I, II, V, VII, and X.

    <p>Prothrombin Time</p> Signup and view all the answers

    Match the following proteins with their roles in the coagulation and complement systems:

    <p>Thrombin = Clotting factor C3 = Complement component V = Clotting factor C5 = Complement component</p> Signup and view all the answers

    What can cause prolonged APTT?

    <p>Circulating anticoagulants</p> Signup and view all the answers

    Which of the following statements about coagulation factors is true?

    <p>Prothrombin and fibrinogen are categorized as substrates.</p> Signup and view all the answers

    Factors VIII and XI are referred to by their common names.

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

    What is the common name for factor IX, which is often associated with hemophilia?

    <p>Christmas factor</p> Signup and view all the answers

    The primary substrate in the coagulation cascade is __________.

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

    Match the coagulation factors to their corresponding roles:

    <p>VII = Activated by tissue factor X = Common pathway enzyme VIII = Co-factor for factor IX II = Prothrombin</p> Signup and view all the answers

    What is the primary function of CD59 in the complement system?

    <p>Inhibiting MAC assembly</p> Signup and view all the answers

    Antithrombin-III provides significant anti-inflammatory properties.

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

    Name two serine protease inhibitors mentioned in the content.

    <p>Heparin cofactor II, α1-antitrypsin</p> Signup and view all the answers

    The activation of the complement system involves the assembly of the __________.

    <p>Membrane Attack Complex (MAC)</p> Signup and view all the answers

    What percentage of the antithrombin activity in normal plasma is derived from AT-III?

    <p>More than 90%</p> Signup and view all the answers

    Activated Partial Thromboplastin Time (aPTT) is related to the observation that hemophiliacs have prolonged clotting time.

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

    Which anticoagulant is effective against factors XIIa and XIa?

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

    In severe cases like septic shock, antithrombin-III is proven to be __________.

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

    Match the following components with their functions:

    <p>CD59 = Inhibits MAC assembly Heparin cofactor II = Serine protease inhibitor Antithrombin-III = Anti-inflammatory properties α2-macroglobulin = Regulates protease activity</p> Signup and view all the answers

    What type of molecules do complete thromboplastins consist of?

    <p>Both phospholipids and proteins</p> Signup and view all the answers

    Which of the following factors is NOT a cofactor in the coagulation cascade?

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

    All enzymes involved in the coagulation cascade are classified as serine proteases.

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

    What is the role of tissue factor in the coagulation cascade?

    <p>Initiates coagulation by triggering the extrinsic pathway.</p> Signup and view all the answers

    The physiological process that removes insoluble fibrin clots is called ______.

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

    Match the following factors with their corresponding group in the coagulation cascade:

    <p>Factor II = Prothrombin proteins Factor VIII = Fibrinogen or thrombin sensitive proteins Factor XI = Contact proteins Factor X = Prothrombin proteins</p> Signup and view all the answers

    Which enzyme digests fibrin to assist in fibrinolysis?

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

    Fibrin polymerization is part of the coagulation process.

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

    What is the primary function of fibrinogen in hemostasis?

    <p>It converts into fibrin to form blood clots.</p> Signup and view all the answers

    The ______ cascade is initiated by tissue factor binding to factor VII.

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

    Which factor is involved in the regulation of fibrinolytic function through the renin-angiotensin-aldosterone system?

    <p>Angiotensin II</p> Signup and view all the answers

    Study Notes

    Coagulation Cascade

    • Coagulation factors are designated by Roman numerals
    • Activation of a factor is indicated by the lowercase "a" next to the Roman numeral
    • Coagulation factors may be categorized as substrates, cofactors, and enzymes
    • Fibrinogen is the main substrate
    • Examples of cofactors include tissue factor, factor V, factor VIII, and Fitzgerald factor
    • All coagulation factors, except factor XIII, are serine proteases when activated
    • Coagulation factors may be categorized into three groups: contact proteins, prothrombin proteins, and fibrinogen or thrombin-sensitive proteins
    • Contact proteins include factors XII, XI, prekallikrein (PK), and high-molecular-weight kininogen (HMWK).
    • Prothrombin proteins include factors II, VII, IX, and X.
    • Fibrinogen or thrombin-sensitive proteins include factors I, V, VIII, and XIII.

    High-Molecular-Weight Kininogen (HMWK)

    • HMWK is a single-chain protein with a molecular weight of 120,000 daltons
    • Cleaved by human urinary kallikrein (HUK) to release kinin
    • Forms a 2-chain protein that retains procoagulant activity
    • Serves as a cofactor for FXI and PK assembly on biologic membranes
    • Docking of HMWK to platelet and EC membranes requires binding to both its heavy and light chains

    Serine Proteases & Inhibitors

    • Serine proteases (thrombin, FXa, elastase, trypsin) are implicated in inflammatory disorders like emphysema, arthritis, and cardiovascular diseases
    • Naturally occurring serine protease inhibitors (antithrombin) regulate these enzymes
    • Antithrombin is the first plasma coagulation regulatory protein identified and assayed
    • It inactivates thrombin, FXa, and the TF/FVIIa complex
    • Antithrombin inhibits numerous enzymes, including factors XIIa, XIa, IXa, protein S, protein C, plasmin, and kallikrein

    Complement System

    • The complement system consists of approximately 22 serum proteins
    • Activated complement fragments can damage self-tissues
    • Cells express regulators of complement activation to protect themselves
    • Abnormalities in these regulators may contribute to autoimmune and inflammatory disorders

    Activated Partial Thromboplastin Time (APTT)

    • Developed from the observation that hemophiliacs have prolonged clotting time
    • APTT reflects the activity of PK, HMWK, and factors XII, XI, VIII, X, V, II, and I
    • APTT may be prolonged due to a factor deficiency or the presence of circulating anticoagulants
    • Normal APTT is less than 35 seconds

    Prothrombin Time (PT)

    • Screens for deficiencies in factors I, II, V, VII, and X
    • PT is the test of choice for these deficiencies

    Fibrinolytic System

    • Fibrinolysis is the process that removes insoluble fibrin clots
    • Catalyzed by the enzymatic digestion of cross-linked fibrin polymers
    • Plasmin is a key enzyme in fibrinolysis, digesting fibrin and fibrinogen to produce smaller fragments
    • Angiotensin II may regulate fibrinolytic function

    Antithrombin (AT-III)

    • More than 90% of the antithrombin activity in normal plasma is from AT-III
    • Exerts anti-inflammatory properties
    • Effective in experimental models of sepsis, septic shock, and disseminated intravascular coagulation (DIC)

    Platelet Plug Formation

    • Platelet plug formation is a part of primary hemostasis
    • Platelets adhere to exposed collagen, leading to platelet activation and degranulation
    • Released mediators include ADP, TXA2, serotonin, and β-thromboglobulin
    • Platelet aggregation (ATP, fibrinogen, GPIIb, GPIIIa) reinforces the platelet plug

    Hemostasis

    • Hemostasis is the process that stops bleeding
    • Involves vascular spasm, platelet plug formation, and coagulation cascade activation
    • Coagulation factors and platelets work together to form a stable clot

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    Description

    Test your knowledge of the coagulation cascade, including the roles and classifications of various coagulation factors. This quiz covers important concepts such as substrates, cofactors, and the specific proteins involved in hemostasis. Perfect for students studying hematology or related fields.

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