endothelial cells and platelets

Question 1

endothelial cells are _____ regulators of hemostasis

Answer 1

central

Question 2

endothelium maintains a balance between ____ and _____ activitities

Answer 2

anti- and pro- thrombotic activitities

Question 3

T or F… anticoagulent factors are expressed under normal conditions

Answer 3

true

Question 4

T or F… pro-coagulant activites are acquired following injury

Answer 4

true

Question 5

fibrinolysis: t-PA cleaves?

Answer 5

plasminogen into plasmin which cleaves fibrin

Question 6

what cleaves fibrin?

Answer 6

plasmin

Question 7

antiplatelet

Answer 7

• intact endothelium prevents contact with ECM
• prostacyclin (PGI2) and nitirc oxide are vasodilators and inhibit platelet adhesion and aggreagtion
• adenosine diphophatase, which degrades ADP, inhibits platelet aggregation

Question 8

anticoagulant

Answer 8

• heparin-like molecules: co-factors that allow antithrombin 3 to inactivate thrombin (factors9a and 10a)
• thrombomodulin: binds thrombin > cleaves and activates protein C along with protein S > inactivates factors 10a and 13a
• tissue factor pathway inhibitor (TFPI) inhibits tissue factor-factor 7a complex and factor 10a

Question 9

prothrombotic properties of injured or activated endothelium

Answer 9

1) activation of platelets
2) von Willebrand factor (vWF)
- producued by endothelial cells
- bound to ECM
- binds to Gp1b on the surafce of platelets

Question 10

tissue factor is produced in response to TNF, IL-1, bacterial endotoxin. It activates and downregulates what?

Answer 10

• activates coagulation

* downregulates thrombomodulin

Question 11

what limits fibrinolysis?

Answer 11

plasminogen activator inhibiot (PAIs)

Question 12

clotting factors binding tofactors _____ and ____, augment theircatalytic activities

Answer 12

9a anad 10a

Question 13

are platelets cells?

Answer 13

NO! they are cellular fragments

Question 14

platelets are critical in ?

Answer 14

hemostasis; formation of hemostatic plug, recruit and concentrate coagulation factors

Question 15

two types of platelet granules?

Answer 15

1) alpha granules

2) dense bodies (delta granules)

Question 16

alpha platelet granules express?

Answer 16

express P-selectin and contain fibrinogen, fibronectin, factors 10 and 13, platelet factor-4, PDGF,TGF-beta

Question 17

dense plateket bodies (delta granules) contain?

Answer 17

contain ADP and ATP, ionized calcium, histamine, serotonin, and epinephrine

Question 18

histamine and serotonin affect on blood vessels?

Answer 18

vasodilation

Question 19

epinephrine affect on blood vessels?

Answer 19

vasoconstriction

Question 20

4 processes of platelets?

Answer 20

1) platelet adhesion
2) activation
3) aggregation
4) platelet-endothelial interactions

Question 21

platelet adhesion initiates? is mediated through?

Answer 21

• initiates clot formation

* mediated through vWF and glycoprotein Gp1b

Question 22

Platelet Activation

Answer 22

release of alpha granules and dense bodies (delta granules)

• production of thromboxane A2
• change in shape to increase surface area to bind to vWF

Question 23

1) Platelet aggreagation bridging interaction?
2) thrombin stabolizes
3) thrombin converts
4) are RBCs and WBCs present?

Answer 23

1) bridge in interactions between fibrinogen and Gp2b/3a receptors
2) thrombin stabilizes the platelet plug via activation of a protease-activated receptor (PAR)
3) thrombin converts fibrinogen to fibrin
4) RBCs and WBCs are also present

Question 24

protease-activtated receptor (PAR) is a ______ hemostatic plug

Answer 24

secondary

Question 25

platelet-endothelial interactions is a balance between opposing effects of

Answer 25

prostacyclin (PGI2) and thromboxane A2 (TxA2)

Question 26

prostacyclin (PGI2) and thromboxane A2 (TxA2) which one dominates?

Answer 26

* prostacyclin (PGI2) = during normal vessels | * thromboxane A2 (TxA2) = during endothelial injury injury (and PGI2 decreases)

Question 27

prostacyclin (PGI2) affect on blood vessels?

Answer 27

vasodilator, inhibits platelet aggregation

Question 28

thromboxane A2 (TxA2) affect on blood vessels?

Answer 28

vasoconstrictor

Question 29

what is the ultimate goal of clinical inhibition of platelet aggregation?

Answer 29

to lower the risk of coronary thrombosis

Question 30

what are two common drugs used to clinically inhibition of platelet aggregation?

Answer 30

aspirin and plavix

Question 31

what is aspirins affect on platelet aggregation?

Answer 31

permanently blocks platelet formation of TxA2 (also used as profilactic for heart probs)

Question 32

what is plavixs affect on platelet aggregation? aka?

Answer 32

plavix (clopidogrel) is an ADP antagonist only | *(ADP is a platelets activator)

Question 33

proteins ___ and ___ work together to activate factos 5a and 8a?

Answer 33

C and S

Question 34

heparin-like molecules are co-factors that allowantithrombin 3 to inactivate?

Answer 34

thrombin, factor 9a and factor 10a

Question 35

prostacyclin (PGI2) and nitric oxide have what affect on blood vessels? inhibit what aspect of platelets?

Answer 35

vasodilators | *inhibit adhesion and aggregation