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55 Cards in this Set
- Front
- Back
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hemostasis
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SPONTANEOUS arrest of bleeding from small vessels like capillaries and venules
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coagulation
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Blood in semisolid jelly-like mass that converts temporary platelet plug to PERMANENT sealing
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platelet plug formation
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1. Breach of blood vessel exposes blood to sub-endothelial collagen
2. Platelets adhere and aggregate, aided by thromboxane A2 |
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Platelet plug formation
Precapillary sphincter constriction Vasoconstriction Pressure of tissue fluid |
Processes that bring about hemostasis
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1. Prick fingertip (or pinna)
2. Time noted after pricking 3. At end of every 30 sec, blood is blotted on filter paper 4. Procedure continues until no blood stain appears 5. Time is noted again (= bleeding time) |
Determination of bleeding time
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bleeding time
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Time interval from onset of bleeding to cessation of blood flow (Normal is about 1-4 minutes)
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thrombocytopenia
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Low platelet count
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idiopathic thrombocytopenic purpura
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Conditions in which THROMBOCYTOPENIA is seen
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thrombocytosis
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High platelet count
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surgical operation
fractures accidents after parturition after splenectomy |
Conditions in which THROMBOCYTOSIS is seen
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purpura
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spontaneous hemorrhagic spots beneath skin or mucus membrane; caused by decreased platelet count (bleeding time is increased, clotting time is normal)
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thrombocytopenic purpura
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AKA primary purpura; purpura due to decreased platelet count
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symptomatic purpura
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purpura caused by allergic reactions or infections
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thrombasthenia purpura
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purpura caused by defective platelet function (platelet count will be normal)
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To convert temporary hemostatic plug into permanent sealing of injured area (if clotting doesn't occur over hemostatic plug, it may get washed away)
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Why should clotting occur over hemostatic plug?
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clotting factors
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Substances involved in blood coagulation; present in inactive state in circulation; at time of clotting these are activated; designated with roman numerals (designated by order of discovery) with 'a' indicating active form of factor
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1. Formation of prothrombin activator (by intrinsic and extrinsic mechanism)
2. Conversion of prothrombin to thrombin by activator 3. Conversion of fibrinogen to fibrin by thrombin and clot formation |
Major steps in clotting
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intrinsic system
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Formation of prothrombin activator by EXPOSURE OF COLLAGEN TO PLATELETS
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extrinsic system
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Formation of prothrombin activator by SUBSTANCES RELEASED BY DAMAGED TISSUES
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fibrinogen
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Factor I
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prothrombin
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Factor II
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tissue thromboplastin (TF)
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Factor III
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Ca++
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Factor IV
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proaccelerin
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Factor V
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ABSENT
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Factor VI
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proconvertin (stable factor)
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Factor VII
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antihemophilic factor
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Factor VIII
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christmas factor
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Factor IX
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stuart prower factor
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Factor X
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plasma thromboplastin antecedent
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Factor XI
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hageman's factor
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Factor XII
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fibrin stabilizing factor
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XIII
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HMW kininogen
Kallikrein Von Willebrandt factor |
additional factors required for clotting (no roman numerals)
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prothrombin activator
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mixture of Xa, Va, PL, ionic Ca
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clotting time
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time interval from onset of bleeding till the appearance of fibrin threads
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hemophilia
christmas disease decrease in concentration of prothrombin or fibrinogen |
conditions that cause increased clotting time
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fibrinolysis
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process by which clot is broken down
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3 hours
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time frame to act in a patient that suffers from stroke
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tPA
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tissue plasminogen activator (drug of choice for emergencies)
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uPA
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urokinase plasminogen activator (in urine)
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anticoagulants
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substances that prevent clotting of blood
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in vivo anticoagulants
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used to prevent coagulation of blood INSIDE the body
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in vitro anticoagulants
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used to prevent coagulation of blood OUTSIDE the body
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heparin
dicoumarol (coumadin, warfarin) |
in vivo anticoagulants
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heparin
sodium citrate (3.8%) double oxalate (ammonium and potassium) EDTA (ethylene diamine tetra acetic acid) |
in vitro anticoagulants
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dicoumarol
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vitamin K antagonist
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vitamin K
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Required for synthesis of factors II, VII, IX, X
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heparin
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Used therapeutically for preventing intravascular thrombosis, during dialysis, MI, ischemic heart disease
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store blood in blood bank: use acid citrate dextrose (ACD) or citrate phosphate dextrose (CPD)
retain fluidity of blood to carryout certain tests in lab |
uses of anticoagulant outside the body
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prothrombin time
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time interval required to convert prothrombin to thrombin and final clot formation (used to measure liver function and as a guide during anticoagulant therapy)
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liver disease
vitamin K deficiency |
conditions in which prothrombin time is increased
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hemophilia
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Blood coagulation disorder that is a recessive sex-linked inherited disease caused by deficiency of factor VIII; occurs only in males (females are carriers); clotting time is prolonged, but bleeding and prothrombin time are normal; symptoms include painful swollen joints; tx with administration of fresh plasma or cryoprecipitate
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christmas disease
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disease due to deficiency of factor IX; AKA hemophilia B
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partial thromboplastin time
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performance indicator of measuring efficacy of both intrinsic and final common coagulation pathway; AKA PTT
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hemophilia
von willebrandt disease christmas disease factor V deficiency vitamin K deficiency |
conditions in which PTT is prolonged
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