161 Bfcp2B Pathology Hemostasis I

Front 1

What are the three main components of hemostasis?

Back 1

Vessel wall, platelets & coagulation proteins

Front 2

What are the anticoagulant effects of the vessel wall under normal conditions?

Back 2

1. Antiplatelet--viaprostacyclin, nitric oxide, andenosine diphosphatase 2. Anticoagulant via heparin-like molecules, antithrombin, thrombomodulin, and tissue factor pathway inhibitors, and 3. Fibrinolytic properties via tissue-type plamsinogen activatotr (t-PA)

Front 3

What are the procoagulant effects of the vessel wall after injury?

Back 3

1. Platelet adhesion--via subendothelial collagen exposure and von Willebrand factor 2. Procoagulant--via tissue factor & phospholipid surface for coagulation proteins, and 3. Antifibrinolytic--via plasminogen activator inhibitors (PAI 1,2, 3)

Front 4

What are normal platelet levels?

Back 4

150-400 bill/L

Front 5

What are some key components of platelet structure?

Back 5

Granules, invaginated canalicular system & microtubules

Front 6

Which granules stain dark in platelets?

Back 6

α-granules

Front 7

What are some diseases associated with a deficiency of α-granules?

Back 7

grey platelet syndrome, Quebec platelet syndrome (relatively mior)

Front 8

What are some dieases associated with δ-granules?

Back 8

Hermansky Pudlak syndrome, Wiskott Aldrich syndrome, Chediak Higashi syndrome, thrombocytopenia, and absent radii syndrome

Front 9

What are some common surface receptors with platelets?

Back 9

GP Ia/IIa & GP Ib/IX/V & GP Iib/IIIa

Front 10

What is Bernard-Soulier disease?

Back 10

A rare, mild platelet disorder in which the platelet receptor for von Willebrand factor (GP Ib/IX/V) is not expressed.

Front 11

What is Glanzman's thrombasthenia?

Back 11

A rare, severe platelet disorder in which the receptor for fibrinogen (GP IIb/IIIa) is not expressed.

Front 12

What is the platelet receptor for collagen?

Back 12

GP Ia/IIa

Front 13

Why is aspirin an effective modulator of inflammation and pain?

Back 13

Aspirin is a Cox 1 & 2 inhibitor which prevents the conversion of arachidonate (dervied from the membrane phospholipids of the platelet) to prostaglandins and thromboxanes.

Front 14

What are steps involved with platelet clot formation?

Back 14

Adhesion, secretion, aggregation, and clot retraction

Front 15

What factors are important for platelet adhesion?

Back 15

von Willebrand factor is a large protein that functions as a connecting bridge between the collagen of the endothelium and GPIb of the platelet. It is especially important in overcoming shear force.

Front 16

What factors are important in the secretion of platelets?

Back 16

Plates secrete ADP and TxA2 (thromboxane) which are important for promoting secondary aggregation for platelets that have already undergone adherence. Additionally, platelet secrete fibrinogen, factor V, factor VIII and factor XIII which are all important for aggregation

Front 17

What are some screening tests that are done for platelet functionality?

Back 17

PFA-100 is the most common standardized test. More specifici tesets include the functional tests of platelet aggregation studies and flow cytometry and the structural studies involving EM. Less commonly, bleeding time is being used, but it is an archaic technique.

Front 18

What coagulation factors are part of the intrinsic pathway?

Back 18

Factors XII, XI, IX, X, II (to thrombin), Fibrinogen (to fibrin)

Front 19

What coagulation factors are part of the extrinsic pathway?

Back 19

Factors VII, X, II (to thrombin), Fibrinogen (to fibrin)

Front 20

Which coagulation factors of the coagulation casscade are cofactors?

Back 20

FVIIIa, TF, Fva

Front 21

What is the Xase complex?

Back 21

Composed of FVIIIa, FIXa, Ca, PL, VIIa, TF?

Front 22

What is the Prothobinase complex?

Back 22

Composed of Fxa, Fva, CA, PL?

Front 23

Which coagulation factors engage in crosstalk in the coagulation cascade?

Back 23

FXa activates FVIIa, FVIIa activates FIXa and vice versa

Front 24

Why is it said that thrombin is a potent protein?

Back 24

It activates FVa, FVIIIa, FXIa, XIIIa, platelets and also interacts with thrombomodulin.

Front 25

Which factors are vitamin K dependent?

Back 25

II, IX & X.

Front 26

Which factors are affiliated with X-liked recessive disease?

Back 26

VIII & IX

Front 27

Which coagulation factor is a transamidase?

Back 27

XIII

Front 28

Why can't hemophiliacs rely on their extrinsic pathway to stop bleeding?

Back 28

The extrinsic pathway only initiates thrombin formation, while the intrinsic pathway propagates it. (Hemophiliacs are FVIII and FIX deficient)

Front 29

Describe the process of physiologic coagulation in the initiation phase.

Back 29

After a breach in the endothelial wall, VWF binds to a platelet which then release Fva from its α-granules. At the same time, tissue factor (TF) gets expressed from a TF bearing cell and binds and activates FVIIa. This complex then activates FXa which, in coordination with FVa on a TF bearing cell produces a small amount of thrombin (FIIa). (It also activates a small amount of FIXa via FVIIa.)

Front 30

Describe the process of physiologic coagulation in the amplification phase.

Back 30

Thrombin continues to produce FVa on activated platelets as well as FXIa and FVIIIa. It also activates TFPI which inhibits TF and forces the intrinsic pathway to produce more thrombin.

Front 31

Describe the process of physiologic coagulation in the propagation phase.

Back 31

Once FXIa is produced, FIXa is produced in greater quantities and complexes with FVIIIa to make a Xase. FXa then complexes with Fva to make a prothrombin complex that produces most of the thrombin, and thus, most of the fibrin.

Front 32

How long does primary hemostasis take?

Back 32

Vessel constriction occurs immediately, platelet adhesion takes seconds, and platelet aggreagation takes minutes.

Front 33

How long does secondary hemostasis take?

Back 33

Coagulation facotrs are activated in seconds and fibrin forms in minutes.

Front 34

How long does fibrinolysis take?

Back 34

Firbrinolytic proteins are activated and minutes, but resolution of thrombus takes hours.

Front 35

How is clotting prevented when laboratory tubes are drawn?

Back 35

Blood is collected into sodium citrate tubes which binds calcium loosely to inhibit coagulation.

Front 36

What does the PTT test for?

Back 36

Abnormalities in the intrinsic pathway.

Front 37

What does the PT test for?

Back 37

Abnormalities in the extrinsic pathway.

Front 38

If only the TT is abnormal what does this tell us?

Back 38

There's a problem with fibrinogen.

Front 39

What does the Stypven time test for?

Back 39

Factor VII deficiency. (Normal Stypven time with long PT indicates a problem with factor VII.)

Front 40

What is a dilute form of russell viper venom used for?

Back 40

It helps detect lupus anticoagulant.

Front 41

What is the reptilase time used for?

Back 41

It tests whether the thrombin time is prolonged due to heparin. (A normal time indicates a heparin problem.)

Front 42

What is the factor XIII assay used for?

Back 42

While factor XIII is not in the coagulation cascade, this urea/acetic acid test or fibrin stabilization test demonstrates an absense or low expression of factor XIII if clots disolve in urea/acetic acid.

Front 43

How is the PT test performed?

Back 43

PT (prothrombin time) can be measured by taking the blood sample stored in sodium citrate and adding back Ca2+ and thromboplastin (TF and phospholipid)

Front 44

How is the aPTT or PTT test performed?

Back 44

The activated partial thromboplastin time is generally started using a negatively charged activator and the addition of phospholipid and calcium to the blood sample stored in sodium citrate.

Front 45

How is a thrombin time test performed?

Back 45

The TT is performed by simply adding thrombin to the blood sample stored in sodium citrate.

Front 46

How are specific factor tests performed?

Back 46

Vendors provide factor deficient plasma that allow for specific identification of factor deficiciencies.