Coagulation I/II

Question 1

Primary Hemostasis

Answer 1

Localized to the area of exposed subendothelial collagen

Platelet plug

Question 2

Secondary Hemostasis

Answer 2

requires platelet membrane surfaces for efficient factor interaction

Question 3

Coagulation factors circulate in the blood as

Answer 3

Zymogens (inactive but ready to strike)

Question 4

Coagulation Factors- Zymogens

Answer 4

FVII, FXI, FIX, FX, Pro-Thrombin (FII)

Question 5

Coagulation Factors- Procofactors

Answer 5

Tissue Factor (TF), FVIII, FV

Question 6

Coagulation Factors are all produced in the

Answer 6

Liver

Question 7

Tissue Factor is expressed by

Answer 7

DAMAGED endothelial cells

Question 8

Thrombin’s activity

Answer 8

Activates platelet phospholid to expose phosphotidyl serine
Thrombin restructures platelet surface
Thrombin activates FVIIIa and FVa which form complex with Ca2+
FVIIIa and FVa increase FXa which cleaves more prothrombin to thrombin
Thrombin cleaves Fibrinogen to fibrin
Thrombin cleaves FXIII to FXIIIa

Question 9

Vitamin K dependent Cofactors

Answer 9

FII, FVII, FIX, FX

have GLA domains that need to be carboxylated to gamma carboxy glutamic acid by vit K dpendent carboxlase

Question 10

Mechanism of Coumadin/ Warfarin

Answer 10

Anti-coagulant that blocks reduction of vitamin K

Question 11

Prothrombin Time (PT)

Answer 11

Measures Extrinsic pathway
Initiated by TF which is EXTRINSIC to circulation
Blood sample collected in citrate to remove any Ca2+, platelets are removed via centrifugation
TF is added to blood with Ca2+ and phospholipids and you measure how long it takes clot to form.

Question 12

Thromboplastin

Answer 12

Phospholipids + TF = thromboplastin

Part of Prothrombin Time Assay for Extrinsic Pathway

Question 13

Partial Thromboplastin Time (PTT)

Answer 13

Evaluates INTRINSIC pathway

Question 14

Partial Thromboplastin

Answer 14

Phospholipids - TF = partial thromboplastin

Part of partial thromboplastin time for Intrinsic pathway

Question 15

Heparin/ Antithrombin (AT) System

Answer 15

AT is Serine Protease Inhibitor (SERPIN)
Inactivates all serine protease coagulation factors by IRREVERSIBLE binding
AT by itself is very slow inhibitor of thrombin
Heparin induces conformational change in AT resulting in 10,000 fold increase in activity
AT with Heparin bind to thrombin and decrease its activity

Question 16

Protein C and Protein S

Answer 16

Protein C binds to EPCR to become activated
When activated protein C is bound to protein S,
the complex cleaves FVa and or FVIIIa to inactive form
Protein C and Protein S downregulate FV and FVIII

Question 17

tPA

Tissue Plasminogen Activator

Answer 17

binds to clot on fibrin carboxy terminal lysine residue
tPA cleaves plasminogen to plasmin which degrades clot
tPA cleaves plasminogen which is already found in clot

Question 18

Fibrinogen gets cleaved into

Answer 18

D-dimer

quick way to assess how much clotting is going on

Question 19

Elevated DD dimer

Answer 19

indicates clotting activity
Normal DD levels rule out the presence of significant clot
Abnromale DD clot DOES NOT RULE IN significant clot.
i.e. pulmonary embolous, DVT