12.7 C

Question 1

What is hemostasis?

Answer 1

the cellular and noncellular process that prevents blood loss following injury

Question 2

What are the three main steps of hemostasis?

Answer 2

• platelet plug formation
• coagulation
• firbinolysis

Question 3

What gives a hard clot its tensile strength?

Answer 3

fibrin polymers

Question 4

Platelet plug formation has what two steps?

Answer 4

• platelet adhesion

- platelet aggregation

Question 5

What is Von Willebrand Factor?

Answer 5

a plasma protein that binds collagen and links it to Glycoprotein Ib-V-IX

Question 6

What is glycoprotein Ib-V-IX?

Answer 6

a transmembrane protein found on platelets that binds VWF at the site of injury

Question 7

Where is Von Willebrand Factor produced?

Answer 7

endothelial cells and platelets

Question 8

What are Weibel-Palade bodies?

Answer 8

stores of Von Willebrand Factor found in endothelial cells

Question 9

What are alpha granules?

Answer 9

granules within platelets that store Von Willebrand Factor

Question 10

Describe the quaternary structure of Von Willebrand Factor.

Answer 10

it forms massive multiers

Question 11

What is ADAMTS-13?

Answer 11

a protease that cleaves ultra large Von Willeband Factor into its active unit

Question 12

When Von Willeband Factor is produced, it is in what form?

Answer 12

the ultra large form

Question 13

Most Von Willeband Factor is produced by what cells?

Answer 13

endothelial cells

Question 14

Von Willeband Factor production in endothelial cells is controlled by what?

Answer 14

• induced hormonally

- but also produced constitutively

Question 15

Von Willeband Factor has what two functions?

Answer 15

• platelet adhesion

- factor VIII carrier protein which extends the half life

Question 16

Platelets are cross-linked by what protein?

Answer 16

fibrinogen

Question 17

Describe the structure of fibrinogen?

Answer 17

is bipolar such that it can bind and cross-link two platelets

Question 18

What are the five most signficant platelet activating factors?

Answer 18

ADP, collagen, thrombin, thromboxane A2, epinephrine

Question 19

Where is tissue factor found?

Answer 19

on the surface of endothelial cells, fibroblasts, and platelets

Question 20

How does tissue factor get activated?

Answer 20

by injury to its host cell (fibroblast, endothelial, or platelet)

Question 21

The coagulation cascade can generally be described as a series of what?

Answer 21

zymogen activation steps

Question 22

What is the first and last enzyme activated in the coagulation cascade?

Answer 22

tissue factor to thrombin

Question 23

What enzyme cleaves fibrinogen into a fibrin monomer?

Answer 23

thrombin

Question 24

Which coagulation cascade proteins are Vitamin K dependent?

Answer 24

F2, F7, F9, F10

Question 25

Vitamin K is improtant to the coagulation cascade because it is necessary for what process?

Answer 25

the post-translational gamma-carboxylation of glutamic acid residues, forming gamma-carboxyglutamic acid

Question 26

Why is post-translational gamma-carboxylation of glutamic acid residues important to the coagulation cascade?

Answer 26

- adds a second negative charge so that the residue can bind calcium - binding calcium alters the conformation of prothrombin allowing it to insert into a phospholipid membrane on a platelet

Question 27

How does Warfarin prevent clotting?

Answer 27

by preventing regeneration of the active form of vitamin K

Question 28

Why is prothrombin insertion into the platelet plasma membrane important?

Answer 28

because only then can it interact with phosphatidylserine, its alloactive cofactor

Question 29

What happens to phosphatidylserine when a platelet gets activated?

Answer 29

it is flipped to the outer leaflet of the plasma membrane

Question 30

Phosphatiylserine is flipped to the outer leaflet of a platelet plasma membrane so that what can occur?

Answer 30

assembly of various complexes important to the coagulation cascade

Question 31

What is a tenase complex?

Answer 31

a complex that forms on platelet membranes in conjunction with PS to generate Factor Xa, which goes on to cleave prothrombin into thrombin

Question 32

What is a prothrombinase complex?

Answer 32

a complex of Factor Xa and prothrombin (FII) that generates thrombin

Question 33

What is the name for FII?

Answer 33

prothrombin

Question 34

What does thrombin do in the coagulation cascade?

Answer 34

it cleaves portions off of fibrinogen to form fibrin monomers which can then spontaneously assemble into multimers

Question 35

What is the importance of Factor VIIIa in the coagulation cascade?

Answer 35

it catalyzes the transglutaminase reaction, covalently cross-linking D domains of fibrin monomers

Question 36

What protein is responsible for fibrinolysis?

Answer 36

plasmin

Question 37

What is plasminogen?

Answer 37

a zymogen produced by the liver which gets cleaved into plasmin for fibrinolysis

Question 38

What is t-PA?

Answer 38

the enzyme that cleaves plasminogen into plasmin for fibrinolysis

Question 39

What are PAI-1 and PAI-2?

Answer 39

enzymes secreted by endothelial cells to inhibit t-PA and thereby inhibit fibrinolysis

Question 40

What is a2-AP?

Answer 40

a protein secreted by the liver that inhibits plasmin and therefore inhibits fibrinolysis

Question 41

What are the end products of fibrinolysis?

Answer 41

E monomers, D monomers, and D dimers