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This is a decreased platelet count caused by decreased platelet production, abnormal platelet distribution, or increased platelet destruction.
Thrombocytopenia
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This is the formation of a clot.
Thrombosis
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This is the enzyme that converts fibrinogen to fibrin.
Thrombin
-
What are the three components of the vascular system?
-
These are spider-like dilations of small vessels.
Telangiectasia
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This is a deficiency of vitamin C that causes decreased levels of hyaluronic acid.
Scurvy
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This is subcutaneous tissue atrophy.
Senile purpura
-
These are cytoplasmic fragments released by megakaryocytes.
Platelets
-
What percent of platelets are in the spleen?
30%
-
What percent of platelets are circulating?
70%
-
What is the lifespan of a platelet?
10 days
-
What is the size of a platelet?
2-4 microns
-
Exposed collagen and subendotheliall cells initiate this first step where platelets adhere to surfaces.
Adhesion
-
In adhesion platelets change from disks to what shape?
Spiny spheres
-
What is required to activate platelet adhesion?
vW factor
-
In what step do platelets cohere to other platelets?
Aggregation
-
This prevents aggregation by inhibiting the activity of enzyme cyclooxygenase.
Asprin
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In this condition platelet autoantibodies of unknown origin are created, there is a spontaneous remission within several weeks.
Increased thrombocytopenic purpura (TTP)
-
In this condition thromboplastin like substances into the peripheral blood initiate a clot that utilizes platelets that causes a diffuse generation of fibrin and thrombin that consume factors and platelets.
Disseminated Intravascular Coagulation (DIC)
-
What are three conditions that cause DIC?
- Adenocarcinoma
- Sepsis
- Liver disease
-
What is the treatment for DIC?
- Eliminate underlying disorder
- Administer heparin
-
What factor initiates the extrinsic pathway?
Tissue thromboplastin (factor III)
-
In the extrinsic pathway what factor stimulates the common pathway?
Factor VIIa (proconvertin)
-
This is a serine protease precursor that is converted to thrombin.
Factor II (prothrombin)
-
What are the three functions of prothrombin?
- Spilts fibrinogen
- Stimulates platelet aggregation
- Activates cofactors and protein C
-
Calcium is required in several steps of coagulation, what factor is calcium?
Factor IV
-
This is the precursor that speeds formation of prothrombin to thrombin.
Factor V (proaccelerin)
-
This factor is nonexistent.
Factor VI
-
This high-molecular weight cofactor has several functions, and is also known as Vwf.
Factor VIII (antihemophilic factor A)
-
This factor is also known as plasma thromboplastin or the Christmas factor.
Factor IX (antihemophilic factor B)
-
This factor can be activated by collagen.
Factor XII (Hageman factor)
-
This factor stabilizes polymerized fibrin monomers.
Factor XIII (fibrin stabilizing factor)
-
This factor is converted to kallikrein.
Prekallikrein (Fletcher factor)
-
What four factors are parts of the prothrombin group?
-
This coagulation group requires vitamin K, is not activated by thrombin, is not consumed during clotting, is not degraded by plasmin, and is stable in stored plasma.
Prothrombin group
-
What are five lab results that indicated DIC?
- Increased PT and APTT
- Decreased fibrinogen/Plt count
- FDP positive
- D-Dimer positive
- Fragmented RBCs
-
Fibrinolytic activation can occur __________ or ___________.
- Intrinsically
- Extrinsically
-
This degrades fibrinogen and some factors
Plasmin
-
What is used to indicate fibrinolytic activation?
FDP
-
This acts as a circulating anticoagulant
Fibrinolytic system
-
These orally administered drugs interfere with the synthesis of the prothrombin family.
Coumarin/warfarin derivatives
-
This screening test is used to conitor couarin therapy by detecting dysfibrinogenemia.
Prothromin Time (PT)
-
PT screens deficiencies of what pathways?
-
What factors are screened in the PT test?
- I, II, V (common)
- VII, X (extrinsic)
-
What is the normal value for PT?
10-12 seconds
-
What are three sources of error in PT?
- Incorrect plasma/sodium citrate ratio
- Inaccurate pipetting
- Hemolyzed and clotted specimens
-
What are four uses of Activated Partial Thromboplastin Time (APTT)?
- To monitor heparin therapy
- Routine screen of coagulation disorders
- Routine screen of intrinsic system
- Aids in detecting circulating anticoagulants
-
How does factor IX activate the common pathway?
- Factor IX is activated
- IXa activates factor X
- Xa activates common pathway
-
What is the normal value for APTT?
25-35 seconds
-
This tech error may shorten APTT test.
Traumatic Phlebotomy
-
What is the normal value for the fibrinogen determination?
150-400 mg/dl
-
What are two things that can cause an invalid low result in the fibrinogen determination?
-
What does INR stand for?
International Normalized Ratio
-
This allows for inter-laboratory correlation so patients can be anticoagulated at comparable levels.
INR
-
This test compensates for differences in reagent systems.
INR
-
The more _______ the reagent, the more reliable is the INR.
Sensitive
-
What is the formula for INR?
INR= patient result/mean normal result
-
Most thrombotic disorders can be treated with INR between ________.
2.0-3.0
-
This test is used to screen for platelet function and dysfunction and hemostasis.
Bleeding time
-
What are for conditions that can cause a prolonged BT?
- Patients taking aspirin
- Thrombocytopenia
- Von Willebrands disease
- Bernard Soulier Syndrome
-
When performing a bleeding time the BP cuff should be inflated to ___ mmHg.
40 mmHg
-
How often should an incision for a bleeding time be blotted?
Every 30 seconds
-
When performing a BT when should you stop timing the test?
As soon as bleeding stops
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