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Hemostasis Tim

J Sarge Hemostasis

Factor I Fibrinogen
Factor II Prothrombin
Factor III Tissue factor
Factor IV Ca++
Factor V Labile factor
Factor VII Stable factor
Factor VIII Antihemophilic factor
Factor IX Christmas factor
Factor X Stuart-Prower factor
Factor XI PTA (plasma thromboplastin antecedent
Factor XII Hageman factor
Factor XIII FSF (fibrin-stabilizing factor)
HMWK High-molecular-weight kininogen, Fitzgerald factor
PF3 Platelet factor 3
VWF von Willebrand factor (carries VIII)
Prekallikrein Fletcher factor, PK
What are platelets? Fragmentation of megakaryocyte cytoplasm originating in the bone marrow
What divides in a megakaryocyte, the nucei or the cytoplasm? Nuclei
How many nuclei will a Promegakaryocyte have? 2-4
How many nuclei should there be before we call the cell a megakaryocyte? 8-32
How many platelets may a maegakaryocyte produce? 2,000 to 7,000
Are some megakaryocytes stored in the lungs? yes
Where are about 1/3 of all platelets stored? In the Spleen
Splenomegaly will do what to the platelets? Will induce large number of plateleats to be stored
Hypersplenism invariably results in what? Thrombocytopenia
What can be done to correct thrombocytopenia? Remove the spleen
How long do platelets survive? 7-10 days
What is normal platelet number in the peripheral blood? 150K-350k/uL
Do platelets have nuclei? No
What are the four main components of hemostasis? Vascular system, Primary Hemostasis, Secondary Hemostasis, Fibrinolytic system
What is the role of the vascular system? Regulation of the rate of blood flow
What is the role of primary hemostasis? Platelets interact with vascular endothelium, formation of primary hemostatic plug which may initiate clotting cascade, maintain vascular integrity
What is the role of secondary hemostasis? Coagulation system, fibrin is the end product, blood clot. Composed of a series of plasma proteins and cofactors interacting. Extrinsic and Intrinsic Cascades
What is the function of the fibrinolytic system? Clot dissolution. Includes specific set of plasma proteins tasked with prevention of hypercoagulability
Describe the different layers of the vessel wall. Intima (inner), media (middle), adventitia (outer)
How does the vascular system prevent bleeding? Vascontriction, Diversion of blood flow, Initiation of contact activation of platelets, Contact activation of the coagulation system
What is fibrinolysis? The action of removing unwanted fibrin deposits and gradually breaking down fibrin into soluble fragments
What mediates fibrinolysis? Plasmin which is generated by t-PA
What does plasmin do? Splits fibrin into smaller pieces until it gets 2 D fragments and an E fragment. (Fibrin Split or Degradation products- FDPs
What can we test for to determine if fibrinolysis has occured? D dimers or FDPs which include the larger pieces (X and Y)
Coagulation is usually measure by what tests? Prothrombin Time (PT) and Partial Tissue Thromboplastin Time (PTT)
What test measures the extrinsic pathway? Prothrombin Time (PT)
What test measures the intrinsic pathway? Partial Tissue Thromboplastin Time (PTT)
The PT test is more sensitive to loss of Factor? than to Factor II? Factor VII
The PT test is inhibited by what drug which inhibits Vitamin K uptake by liver cells? Coumadin
The normal range for the PT test is? 10-13 seconds
What is INR when discussing PT time? International normalized ratio. This is reported in the PT result and allows standardized comparisons of values.
The PTT test is inhibited by? Heparin
The PTT test is most sensitive to intrinsic deficiencies occurring in the cascade prior to Factor? Factor II
When the PT test is prolonged by coumadin, will the PTT test be affected? Yes, it is also prolonged
When an unexplained prolonged PT and/or PTT is encountered clinically, what might be suspected? A Factor deficiency or circulating inhibitor
What might be done to detect a factor deficiency? Different combinations of serum or plasma containing known Factors are added back to the specimen to correct the deficiency
What are the role of platelets? Provide a negatively charged phospholipid surface for fX and pthrombin activation. Release substances that mediate vasocontriction, platelet aggregation, coagulation, and vascular repair. Provide surface membrane glycoproteins which attach to other p-lets
What activates a platelet? Disruption of vascular endothelium. Exposure of collagen in basement membrane attracts and stimulates circulating platelets
Is adhesion reversible? Yes
What does a platelet need to initially adhere to exposed collagen? von Willenbrand Factor, Collagen and GPIb
What happens after the initial adherence to exposed collagen? Release of ADP from dense bodies.Other platelets are activated through interaction of collagen or other mediators (thrombin, ADP , or TXA2) Immediate shape change and pseudopodia. Formation of primary hemostaic plug
Is aggregation reversible? No
Steps in aggregation 1... Release of more ADP form dense bodies; attraction of adjacent platelets initiating aggregation. Need ATP for energy and Ca++, GPIIb, IIIa and fibrinogen. Fibrinogen activates the GPIIb/IIIa complex. Release of PF3 which further simulates coag process
Steps in aggregation 2... Release of PF4 and other factors promoting clot formation. Initiation of coag cascades and formation of fibrin. Formation of secondary hemostatic plug-irreversible process
What platelet granules secrete factors throughout the whole process? Alpha granules
Here are other secretions that are essential for clot formation. Beta-throboglobulin, PF4, thrombospondin, and PDGF are some of the factors secreted and are used as activation markers.
What is Brecker-Cronkite Method? A manual platelet counting method. 1:100, phase-microscopy and 1% ammonium oxalate. est 11-15% error
What is Rees-Ecker Method? A manual platelet counting method. 1:200, light microscopy and sodium citrate, est 16-25% error
What are some reasons for false high platelet counts from automated instrumentation? Presents of abnormal proteins; macroglobulinemia, uremia, multiple myeloma. Patient undergoing chemotherapy or irradiation may be high due to leukocyte or platelet fragmentation. Contamination from bacteria or other particulate matter.
What are some reasons for false low platelet counts from automated indtrumentation? Sample containing platelet aggultinins and/or cold agglutinins. Satellite phenomenon. Platelet aggregates may be counted as platelets,or not counted at all. Giant platelets counted as RBCs
What is a Bleeding Time Test? The amount if time required for a standard sized wound to stop bleeding
Describe the Simplate-Template method for a bleeding time test. Normaltime is 2.5-9.5 minutes; uses a BP cuff to 40mm/Hg; cut on forearm and bleeding is timed; uses a spring-loaded blade (most commonly used)
What factors are in the fibrinogen group? 1, 5, 8 13
What factors are in the contact group? 11 and 12
What factors are in the prothrombin group? 2, 7, 9, 10
Created by: 1414395397