Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
27 Cards in this Set
- Front
- Back
|
What two things make up a thrombus?
|
this is formed from a platelet plug and a fibrin clot
|
|
|
What are the 3 major events that take place in response to injury in the vascular system?
|
Vasoconstriction
Platelet plug Fibrin clot |
|
|
What produces platelets? what is the process called?
|
these are produced by bone marrow megakaryocytes
this is called thrombopoiesis |
|
|
What are the 3 types of granules found in platelets?
|
Dense granules
alpha granules dense tubular system |
|
|
what is stored in platelet dense granules?
|
high levels of Ca2+ and ADP
|
|
|
what is stored in platelet alpha granules?
|
von Willebrand factor
fibrinogen factor V serotonin and platelet derived growth factor |
|
|
what is stored in platelet dense tubular systems?
|
Ca2+
|
|
|
What does intact healthy endothelial cell release into the plasma?
|
PGI2 (postacyclin)
|
|
|
How does PGI2 affect platelets?
|
PGI2 works on the cAMP pathway, lowering intracellular calcium in platelets. this STOPS platelet plug formation
|
|
|
what is the inital signal for the formation the platelet plug?
|
this exposure of collagen in the basal lamina
|
|
|
What is the first thing to interact with the exposed collagen in the basal lamina? What happens to it?
|
serum von Willebrand factor binds exposed collagen
binding to collagen changes vWF (due to high sheer force) which allows it to bind to platelet Gb1b/IX |
|
|
what platelet receptor binds the vWF on exposed collagen?
|
Gb1b/IX
this will also bind clotting factor VIII |
|
|
How do arteries and veins differ in platelet plug vs. fibrin clot levels?
|
thrombi located in arteries are typically more platelet plug, due to high sheer forces
|
|
|
what do most platelet agonists bind to?
|
Gq-linked receptors on platelets
|
|
|
what is the most potent agonist of platelets?
|
thrombin
|
|
|
What do thrombin and TxA2 do to platelets?
|
these activate PLA2 (and increase Ca2+)
PLA2 increases AA, which increases TxA2 production again! (activating platelets) |
|
|
what are the roles that TxA2 plays?
|
this activates other platelets
also plays a role in stimulating the secretion of contents from ALL the granules of platelets |
|
|
What does ADP do to platelets? where is it found?
|
this is found in dense granules
this is a potent platelet aggregation agent |
|
|
how does plavix work?
|
this blocks ADP receptors on platelets, inhibits platelet aggregation by 30%
|
|
|
How does degranulation affected the surface area of activated platelets?
|
this results in a 60% increase in surface area
|
|
|
how does increasing intracellular calcium affect the shape of platelets?
|
this activated MLC-P (myosin light chain proteins) which results in actin cytoskeleton alterations/shape change/movements
|
|
|
what glycoproteins are only exposed in activated platelets? (after shape change occurs)
|
Gp IIb/IIIa
|
|
|
what phospholipid moves from the inner to outer surface of platelets? what does this affect? what does this induce the binding of?
|
phosphatidylserine moves, this produces a negative charge on the platelets surface (after activation)
this induces the binding of clotting factors VIIIa and Va |
|
|
What does exposed Gp IIb/IIIa on activated platelets bind do?
|
this binds to fibrinogen, this allows two activated platelets to bind together
|
|
|
what do the GP IIb/IIIa functional dimers bind to? what motif?
|
these bind to an aeg-gly-asp (RGD) motif on fibriniogen
this is on the gamma chain of the fibriniogen |
|
|
How does Integrillin work?
|
this is a drug that mimics the RGD sequence on fibrinogen, preventing platelet aggregation (by not allowing their GP IIb/IIIa groups to bind)
|
|
|
How does aspirin work to prevent clots?
|
aspirin inhibits COX-1, which prevents PGI2 synthesis, and thus prevents TxA2 synthesis. preventing platelet aggregation signalling
|
