Hemostasis Intro 1 Flashcards Preview

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Flashcards in Hemostasis Intro 1 Deck (32):
1

What is the converging factor between the 2 pathways?

factor X

2

Why is it called the extrinsic pathway?

requires tissue factor to function

3

Why is it called the intrinsic pathway?

the components are contained w/I the plasma

4

How is the extrinsic pathway initiated?

tissue factor binds to factor VIIa

5

How is the intrinsic pathway initiated?

contact factors activate factor XI

6

What are the contact factors?

factor XII, prekallikrein, HMWK

7

What is the common pathway?

events after activation of factor X (the convergence)

8

Intrinsic pathway steps?

activation of contact factors, leading to activation of factor XI, then activation of factor 9, then with cofactor VIIIa activation of factor X, then with cofactor Va, activate factor II, converting fibrinogen to fibrin

9

Where are the proteins of the coagulation cascade synthesized?

in the liver

10

What is bleeding diathesis?

bleeding tendency or predisposition

11

What are the exceptions to liver production of coagulation cascade proteins?

1. tissue factor (surface of many cells)
2. VWF (endothelial cells and megakaryocytes)

12

Where is tissue factor synthesized?


Q

on the surface of many cells

13

Where is VWF synthesized?

endothelial cells and megakaryocytes

14

Where is factor VIII produced?

the liver, spleen, lung, kidney

15

What does the suffix "a" indicate?

the activated form

16

Which factor has the shortest half life? Why is this important?



factor VII; it's one of the first factor to deplete in disease

17

Almost all of the enzymes in the coagulation cascade are _____.

serine proteases

18

Inactive precursor proteins are called ____.

zymogens

19

Zymogens that become active serine proteases include ____ (7).

1. factor XII (12)
2. prekallikrein
3. factor XI (11)
4. factor IX (9)
5. factor X (10)
6. factor VII (7)
7. factor II (2- prothrombin)

20

Which are the vitamin-K dependent factors? (6)

1. factor II (2)
2. factor VII (7)
3. factor IX (9)
4. factor X (10)
5. anticoagulant protein C
6. protein S

21

What do the vitamin-K dependent factors have in common?

Gla domains that bind Ca++ to cause conformational change of protein into active form

22

Why is factor XIII (13) unique? What does it do?

enzyme that is not a serine protease- it's a transglutaminase; covalently links fibrin molecules together to form a stable clot

23

Why are cofactors important in the coagulation cascade?

they initiate and accelerate enzymatic rxns by bringing components together and orienting them correctly

24

Name the cofactors in the coag. cascade. (4)

1. tissue factor
2. factor VIII (8)
3. factor V (5)
4. HMWK

25

What protein makes the actual clot?

fibrinogen

26

What does VWF stand for?

von Willebrand Factor

27

What does VWF do?

it's the carrier protein for factor VIII (8) in the plasma

28

Where is VWF produced and stored?

Weibel-Palade bodies in endothelial cells and in alpha-granules of platelets

29

Why does VWF bind to factor VIII (8)?

to protect it (prolong its half life)

30

What happens in VWF-deficient pts?


Q

low levels of circulating factor VIII (8), leading to a bleeding disorder similar to hemophilia A

31

What do enzyme complexes consist of?

protease + cofactor + phospholipid surface + Ca++

32

Extrinsic pathway steps?

tissue factor binds to factor VIIa, which activates factor X, Xa with cofactor Va activates factor II to IIa, which then converts fibrinogen to fibrin