General principles of Hemostasis

Question 1

Two methods of anti-clotting:

Answer 1

cascade inhibition

clot lysis

Question 2

Membrane protein on platelets that binds collagen:

Answer 2

GP Ia

Question 3

Membrane protein on collagen that binds vW factor:

Answer 3

GP Ib

Question 4

Membrane proteins on platelets that bind fibrinogen:

Answer 4

GP IIb-IIIa

Question 5

Coag pathway with factors all present in blood:

Answer 5

intrinsic

Question 6

Coag pathway that needs TF from subendothelium:

Answer 6

Extrinsic

Question 7

Coag cascade triggered by:

Answer 7

Extrinsic pathway – exposed TF

Question 8

Factors of Intrinsic pathway:

Answer 8

XII(a) –> XI(a) –> IX(a) –> (+ VIII(a)) –> X (start of common pathway)

Question 9

Factors of Extrinsic pathway:

Answer 9

TF + VIIa –> X(a)–start of common pathway

Question 10

Cofactor of Xa in common pathway?

Answer 10

Va

Question 11

Xa does what?

Answer 11

prothrombin –> thrombin

Question 12

thrombin does what?

Answer 12

inhibits extrinsic and triggers Intrinsic

**fibrinogen—»> FIBRIN = CLOT

Question 13

Intrinsic cofactor of IXa:

Answer 13

VIIIa

Question 14

Where does TF come form:

Answer 14

“Hidden cells” exposed during injury

Microparticles floating in blod

Endothelial cells and monocytes

Question 15

Breaks up clot to form FDPs:

Answer 15

plasmin

Question 16

how do you get plasmin?

Answer 16

plasminogen + t-PA

Question 17

Inhibits cofactors VIIIa and Va:

Answer 17

protein C and S

Question 18

Inhibits A LOT of coag factors?

Answer 18

ATIII

Question 19

inhibits TF/VIIa complex:

Answer 19

TFPI

Question 20

Old school way to evaluate platelet response to vascular injury:

Answer 20

Template Bleeding time

Question 21

Detects platelet function abnormalities:

Answer 21

Platelet aggregation

Question 22

Why do you put coag tests in a citrate tube?

Answer 22

to get rid of Ca2+

Question 23

Prothrombin Time (PT) measures?

Answer 23

Extrinsic pathway

**uses thromboplastin in vitro in place of TF

Question 24

PT used to test:

Answer 24

Factor VII

• made by liver
• needs vit K
• decreased by Coumadin (warfarin)
• SHORT half life

Question 25

Used instead of PT?

Answer 25

INR

Question 26

When should you order an INR?

Answer 26

assess liver function

monitor coumadin therapy

diagnose DIC

assess pre-OP status

Question 27

Partial Thromboplastin Time measures?

Answer 27

Intrinsic pathway

Question 28

When is PTT increased?

Answer 28

hemophilia A and B

DIC

heparin

inhibitiors?

Question 29

When to order PTT?

Answer 29

Hx of abnormal bleeding

monitor heparin therapy

dx DIC

dx antiphospholipid antibody

assess pre-OP status

Question 30

Thrombin time tests?

Answer 30

conversion of fibrinogen to fibrin

**bypasses intrinsic/extrinsic pathways

Question 31

TT increased?

Answer 31

decreased fibrinogen

or

increased FDPs

Question 32

Why order a D-Dimer?

Answer 32

rule OUT a clot

VERY sensitive

Question 33

Adds cross-links to fibrin:

Answer 33

factor XIII

Question 34

When would you see a decrease in fibrinogen?

Answer 34

DIC

Massive bleed