Coagulation

• Phases of hemostasis

  1. Primary hemostasis: Forms an platelet plug (platelet aggregation)

  2. Secondary hemostasis: formation fibrin strand

  3. Fibrinolysis: dissolves blood clots
• Extrinsic pathway

  Initiated by factor III (tissue factor)
• Intrinsic pathway

  • Begins when factor XII or the Hageman factor is
  • activate when exposed to collagen, kallikrein, and high molecular weight kininogen (HMWK)
• Common pathway

  1. Begins when factor Xa, Va, and calcium bind together, forming a prothrombinase complex

  2. Prothrombinase complex activates prothrombin into thrombin

  3. Thrombin cleaves fibrinogen into fibrin

  4. Thrombin cleaves the stabilizing factor XIII
• Thrombin functions

  activate

  • platelets
  • activating factors V, VIII, and IX
• Fibrin

  A long, thin protein with branches produced at the end of the coagulation cascade when fibrinogen (factor I) is converted to fibrin, which stabilizes the blood clot
• Goal of coagulation

  To form a stable blood clot to stop bleeding and allow time for the tissue to be repaired
• von Willebrand disease

  deficiency in von Willebrand

  • non-functional factor VIII
  • PLT can't adhesion
• Hemophilia

  • Caused by genetic mutations in clotting factor genes and can be passed on from parent to child
• what conditions cause an increased in thrombin

  • hypofibrinogenemia
  • heparin therapy
  • increase fibrin - degradation production
• the end product between platelets and plasma coagulation factor is

  fibrin
• how does heparin affect clotting

  neutralize the effect of thrombin
• how is serum different from plasma

  serum has no fibrinogen
• how is fibrinogen converted to fibrin

  thrombin
• fibrinogen acted on by thrombin from

  fibrin monomer and peptides
• the substance active in splitting fibrin, fibrinogen, and fragment is

  plasmin
• the final stage of coagulation pathway involves the conversion of

  factor I (fibrinogen) to fibrin clot
• prothrombin is

  a protein formed by the liver in the presence of vitamin K
• how does aspirin affect clotting

  prolong the bleeding time
• fibrin monomer polymerize to form

  fibrin polymer
• plasminogen is activated by

  proteolytic enzymes
• how do protein C stop clotting

  inactivate factor VIII
• prothrombin is converted to thrombin by

  factors X and V, platelet factor 3, and calcium
• heparin is released by

  mast cell
• platelet aggregation is accomplished by the release of

  adenosine diphosphate
• leaving a tourniquet too long can result in

  hemoconcentration
• correct ratio of blood to anticoagulation in PTT and protime is

  9:1
• if a tube for PT is not fill completely the result will be

  prolong
• the reagent use for PTT is

  phospholipid
• the test that detect IgG inhibitor of phospholipid is

  lupus anticoagulant
• bleeding time test measure

  platelet adhesion and aggregation
• low temp. when performing prothrombin time will result in

  shorter time
• PT range

  11 - 14 sec
• partial thromboplastin reagent is a substitute for

  platelet factor
• PTT measure what pathway

  intrinsic pathway
• puncture site for bleeding time test is

  forearm
• end-point detection systems rely on the principle of

  conduction or impedance of an electrical current by fibrin
• concentration of CaCl2 used as reagent in prothrombin time is

  0.002 molar
• thrombin test measure

  fibrinogen
• the test that evaluate platelet function is

  platelet aggregometry