Hemostasis: Blood coagulation and fibirinolysis - Part 2

Question 1

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

Answer 1

Convert soluble fibrinogen to insoluble fibrin

Question 2

The conversion of fibrinogen to fibrin requires what?

Answer 2

Thrombin

Question 3

The formation of Thrombin occurs via which 2 pathways?

Answer 3

1) Intrinsic

2) Extrinsic

Question 4

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

Answer 4

Tissue factor (Factor III or Thromboplastin)

Question 5

Thromboplastin is also known as what?

Answer 5

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

Question 6

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

Answer 6

Tissue factor (Thromboplastin / Factor III)

Question 7

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

Answer 7

Calcium
Platelet phospholipids
Factor X.

Question 8

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

Answer 8

Factor XII (Hageman factor)

Question 9

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

Answer 9

Hageman factor

Question 10

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

Answer 10

XI –> XIa

Question 11

Factor XIa of the intrinsic pathway activates what?

Answer 11

IX —> IXa

Question 12

Thrombin (IIa) activates what in the intrinsic pathway?

Answer 12

VIII –»> VIIIa

Question 13

What in the intrinsic pathway activates factor X

Answer 13

IXa,
VIIIa,
platelet phospholipids and Ca2+

Question 14

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

Answer 14

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

Question 15

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

Answer 15

Va,
Tissue phospholipids,
Ca2+
- Forms prothrombinase complex

Question 16

What does the prothrombinase complex do in the common pathway?

Answer 16

Splits prothromin (II) to thrombin (IIa)

Question 17

What factor forms Fibrin?

Answer 17

Thrombin (IIa)

Question 18

What is the role of Factor XIIIa?

Answer 18

• Covalently cross links fibrin monomers to form cross-linked fibrin
• Converts the fibrin polymer (soft clot) to a stable polymer (hard clot)

Question 19

Fibrinogen is a ____ that is synthesized by the ____.

Answer 19

Plasma protein

liver

Question 20

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

Answer 20

Aggregate;
Hydrogen bonds;
Fibrin polymer (soft clot)

Question 21

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

Answer 21

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

Question 22

Factor XIIIa is a…

Answer 22

Highly specific transglutaminase

Question 23

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

Answer 23

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

Question 24

LAB TESTS: defect in clotting cascade results in ______

Answer 24

increased clotting time

Question 25

LAB TESTS: An extrinsic pathway defect results in:

Answer 25

Increased prothrombin time (INR)

Question 26

LAB TESTS: An intrinsic pathway defect results in:

Answer 26

Increased APTT

Question 27

Vitamin K is required for the hepatic synthesis of what?

Answer 27

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

Question 28

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

Answer 28

Glutamic acid

Question 29

What is the coenzyme for gamma-carboxylase?

Answer 29

Vitamin K

Question 30

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

Answer 30

Gamma-carboxyglutamate (Gla)

Question 31

Gamma-carboxylation allows Ca2+ binding because of what?

Answer 31

2 adjacent negatively charged carboxylate groups

Question 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?

Answer 32

phospholipids on the platelet membrane

Question 33

What is INR (Prothrombin time)?

Answer 33

A very sensitive indicator of vitamin K deficiency