Hemostasis: Blood coagulation and fibirinolysis - Part 2 Flashcards Preview

Medical Biochemistry > Hemostasis: Blood coagulation and fibirinolysis - Part 2 > Flashcards

Flashcards in Hemostasis: Blood coagulation and fibirinolysis - Part 2 Deck (33):
1

In general, the aim of the third step of Hemostasis, Blood Coagulation (secondary hemostasis), is what?

Convert soluble fibrinogen to insoluble fibrin

2

The conversion of fibrinogen to fibrin requires what?

Thrombin

3

The formation of Thrombin occurs via which 2 pathways?

1) Intrinsic
2) Extrinsic

4

Tissue injury initiates the release of what to being the extrinsic pathway.

Tissue factor (Factor III or Thromboplastin)

5

Thromboplastin is also known as what?

Factor III (Tissue factor) - initiator of Extrinsic pathway.

6

Factor VII, which is part of the extrinsic pathway, is activated by what?

Tissue factor (Thromboplastin / Factor III)

7

Factor VIIa and tissue factor, in the presence of ____ and ____ activate _______.

Calcium
Platelet phospholipids
Factor X.

8

Rough endothelial surface, due to pathological processes, lead to the exposure of collagen, which initiates what in the Instrinsic pathway?

Factor XII (Hageman factor)

9

What is factor XII, the first factor initiated in the Intrinsic pathway, also known as?

Hageman factor

10

Factor XIIa, a factor in the Intrinsic pathway, activated what?

XI --> XIa

11

Factor XIa of the intrinsic pathway activates what?

IX ---> IXa

12

Thrombin (IIa) activates what in the intrinsic pathway?

VIII -->>> VIIIa

13

What in the intrinsic pathway activates factor X

IXa,
VIIIa,
platelet phospholipids and Ca2+

14

What does Thrombin (IIa) activate in the common pathway?

V --> Va;
Firbinogen (I) ----> Fibrin (Ia);
XIII--> XIIIa

15

What does Xa combine with in the common pathway? To form what?

Va,
Tissue phospholipids,
Ca2+
- Forms prothrombinase complex

16

What does the prothrombinase complex do in the common pathway?

Splits prothromin (II) to thrombin (IIa)

17

What factor forms Fibrin?

Thrombin (IIa)

18

What is the role of Factor XIIIa?

-Covalently cross links fibrin monomers to form cross-linked fibrin

-Converts the fibrin polymer (soft clot) to a stable polymer (hard clot)

19

Fibrinogen is a ____ that is synthesized by the ____.

Plasma protein
liver

20

The fibrin monomers _______ and are linked to each other via _______, forming the ________.

Aggregate;
Hydrogen bonds;
Fibrin polymer (soft clot)

21

Specifically, to form the covalent bond, XIIIa acts to do what?

Amino group of lysine on one fibrin molecule + amide nitrogen of glutamine on another fibrin molecule = covalent bond

22

Factor XIIIa is a...

Highly specific transglutaminase

23

Ultimate aim of hemostasis is the conversion of ____ to ____ and stabilization of _____ which requires ___.

Firbinogen
Fibrin (4c)
Fibrin (6c)
Thrombin (IIa)

24

LAB TESTS: defect in clotting cascade results in ______

increased clotting time

25

LAB TESTS: An extrinsic pathway defect results in:

Increased prothrombin time (INR)

26

LAB TESTS: An intrinsic pathway defect results in:

Increased APTT

27

Vitamin K is required for the hepatic synthesis of what?

Prothrombin (Factor II)
VII
IX
X
Proteins C and S

28

Which amino acid residues of Proteins C and S are acted upon by Vitamin K dependent gamma-carboxylation?

Glutamic acid

29

What is the coenzyme for gamma-carboxylase?

Vitamin K

30

gamma-carboxylation forms mature clotting factors that contains _____ and is capable of subsequent activation?

Gamma-carboxyglutamate (Gla)

31

Gamma-carboxylation allows Ca2+ binding because of what?

2 adjacent negatively charged carboxylate groups

32

Once gamma-carboxylation allows Ca2+ binding because of two adjacent negatively charged carboxylate groups, The clotting factor-Ca2+ complex can then bind to what?

phospholipids on the platelet membrane

33

What is INR (Prothrombin time)?

A very sensitive indicator of vitamin K deficiency