Exam 3 - Coagulation Flashcards
1
Q
prostacyclin
A
- PGI2
- type of prostaglandin
- secreted by endothelial cells
- acts as a vasodilator
- inhibits platelet aggregation
2
Q
nitric oxide
A
- NO
- secreted by endothelial cells
- acts as a vasodilator
- inhibits platelet aggregation
3
Q
CD39
A
- enzyme in the plasma membrane of endothelial cells
- active site faces the blood
- breaks down ADP
- inhibits platelet aggregation
4
Q
von Willebrand’s factor
A
- protein produced by endothelial cells
- binds to both collagen and platelets
- binding of glycoprotein receptors on the platelet’s membrane to VWF anchors the platelets to site of injury against force of blood flow
5
Q
platelet release reaction
and products released
A
- platelets contain secretory granules; when platelets stick to collagen, they degrandulate and release their products
- products released:
- adenosine diphosphate (ADP)
- serotonin
- thromboxane A2 (a prostaglandin)
6
Q
platelet plug
A
- ADP and thromboxane A2 released during platelet release reaction cause additional platelets to aggregate at the site of injury, forming a platelet plug
- this plug must be reinforced with fibrin strands
7
Q
fibrinogen and fibrin
A
- fibrinogen: soluble, liquid plasma protein
- fibrin: insoluble, solid fibrous protein
- activated platelets activate plasma clotting factors, converting fibrinogen into fibrin
- the plasma membrane of platelets has receptors for fibrinogen and fibrin, which promotes platelet aggregation and stabilizes the platelet plug
8
Q
clot retraction
A
contraction of the platelet mass that forms a more compact and effective plug
9
Q
serum
A
- fluid that is squeezed from the clot during clot retraction
- plasma without fibrinogen
10
Q
vitamin K-dependent clotting factors
A
- factor II
- factor VII
- factor IX
- factor X
- these clotting factors cannot be synthesized by the liver unless vitamin K is present
11
Q
factor XII
A
- protease
- first factor activated in the intrinsic pathway
12
Q
factor II
A
- prothrombrin
- vitamin K-dependent clotting factor
13
Q
intrinsic pathway
A
- the pathway that produces a clot of blood left in a test tube without the addition of any external chemicals
- initiated by exposure of plasma to hydrophilic surfaces in vitro (i.e. glass of a test tube) or to negatively charged structures such as collagen, polyphosphates, and neutrophil extracellular traps (NETs) in the exposed structures of a wound in vivo
- contact pathway
- plays an amplification role, increasing the clotting cascade initiated by the extrinsic pathway
14
Q
extrinsic pathway
A
- damaged tissues release a chemical that initiates a “shortcut” to the formation of fibrin
- clot formation is initiated by tissue factor that becomes exposed to factor VII and VIIa in the blood and forms a complex with factor VIIa
- the tissue factor greatly increased the ability of factor VIIa to activate factor X and factor IX
- clot formation is initiated by tissue factor that becomes exposed to factor VII and VIIa in the blood and forms a complex with factor VIIa
- initiates clot formation in vivo
15
Q
prothrombin
A
inactive glycoprotein that is converted into thrombin
16
Q
thrombin
A
active enzyme that converts fibrinogen into fibrin monomers