This is a decreased platelet count caused by decreased platelet production, abnormal platelet distribution, or increased platelet destruction.
This is the formation of a clot.
This is the enzyme that converts fibrinogen to fibrin.
What are the three components of the vascular system?
These are spider-like dilations of small vessels.
This is a deficiency of vitamin C that causes decreased levels of hyaluronic acid.
This is subcutaneous tissue atrophy.
These are cytoplasmic fragments released by megakaryocytes.
What percent of platelets are in the spleen?
What percent of platelets are circulating?
What is the lifespan of a platelet?
What is the size of a platelet?
Exposed collagen and subendotheliall cells initiate this first step where platelets adhere to surfaces.
In adhesion platelets change from disks to what shape?
What is required to activate platelet adhesion?
In what step do platelets cohere to other platelets?
This prevents aggregation by inhibiting the activity of enzyme cyclooxygenase.
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?
What is the treatment for DIC?
Eliminate underlying disorder
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?
Stimulates platelet aggregation
Activates cofactors and protein C
Calcium is required in several steps of coagulation, what factor is calcium?
This is the precursor that speeds formation of prothrombin to thrombin.
Factor V (proaccelerin)
This factor is nonexistent.
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.
What are five lab results that indicated DIC?
Increased PT and APTT
Decreased fibrinogen/Plt count
Fibrinolytic activation can occur __________ or ___________.
This degrades fibrinogen and some factors
What is used to indicate fibrinolytic activation?
This acts as a circulating anticoagulant
These orally administered drugs interfere with the synthesis of the prothrombin family.
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?
What are three sources of error in PT?
Incorrect plasma/sodium citrate ratio
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?
This tech error may shorten APTT test.
What is the normal value for the fibrinogen determination?
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.
This test compensates for differences in reagent systems.
The more _______ the reagent, the more reliable is the INR.
What is the formula for INR?
INR= patient result/mean normal result
Most thrombotic disorders can be treated with INR between ________.
This test is used to screen for platelet function and dysfunction and hemostasis.
What are for conditions that can cause a prolonged BT?
Patients taking aspirin
Von Willebrands disease
Bernard Soulier Syndrome
When performing a bleeding time the BP cuff should be inflated to ___ 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?