General principles of Hemostasis Flashcards Preview

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Flashcards in General principles of Hemostasis Deck (34)
1

Two methods of anti-clotting:

cascade inhibition

clot lysis

2

Membrane protein on platelets that binds collagen:

GP Ia

3

Membrane protein on collagen that binds vW factor:

GP Ib

4

Membrane proteins on platelets that bind fibrinogen:

GP IIb-IIIa

5

Coag pathway with factors all present in blood:

intrinsic

6

Coag pathway that needs TF from subendothelium:

Extrinsic

7

Coag cascade triggered by:

Extrinsic pathway -- exposed TF

8

Factors of Intrinsic pathway:

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

9

Factors of Extrinsic pathway:

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

10

Cofactor of Xa in common pathway?

Va

11

Xa does what?

prothrombin --> thrombin

12

thrombin does what?

inhibits extrinsic and triggers Intrinsic

**fibrinogen--->>> FIBRIN = CLOT

13

Intrinsic cofactor of IXa:

VIIIa

14

Where does TF come form:

"Hidden cells" exposed during injury

Microparticles floating in blod

Endothelial cells and monocytes

15

Breaks up clot to form FDPs:

plasmin

16

how do you get plasmin?

plasminogen + t-PA

17

Inhibits cofactors VIIIa and Va:

protein C and S

18

Inhibits A LOT of coag factors?

ATIII

19

inhibits TF/VIIa complex:

TFPI

20

Old school way to evaluate platelet response to vascular injury:

Template Bleeding time

21

Detects platelet function abnormalities:

Platelet aggregation

22

Why do you put coag tests in a citrate tube?

to get rid of Ca2+

23

Prothrombin Time (PT) measures?

Extrinsic pathway

**uses thromboplastin in vitro in place of TF

24

PT used to test:

Factor VII
-made by liver
-needs vit K
-decreased by Coumadin (warfarin)
-SHORT half life

25

Used instead of PT?

INR

26

When should you order an INR?

assess liver function

monitor coumadin therapy

diagnose DIC

assess pre-OP status

27

Partial Thromboplastin Time measures?

Intrinsic pathway

28

When is PTT increased?

hemophilia A and B

DIC

heparin

inhibitiors?

29

When to order PTT?

Hx of abnormal bleeding

monitor heparin therapy

dx DIC

dx antiphospholipid antibody

assess pre-OP status

30

Thrombin time tests?

conversion of fibrinogen to fibrin

**bypasses intrinsic/extrinsic pathways

31

TT increased?

decreased fibrinogen

or

increased FDPs

32

Why order a D-Dimer?

rule OUT a clot

VERY sensitive

33

Adds cross-links to fibrin:

factor XIII

34

When would you see a decrease in fibrinogen?

DIC

Massive bleed