2) Primary hemostasis Flashcards
coag tube of choice
Na citrate
factors used up in serum
fibrinogen
prothrombin
V
VIII
XIII
4 categories of coagulation-related proteins circulating in inactive form
- procoagulants
- inhibitors of coagulation
- profibrinolysins
- inhibitors of fibrinolysis
3 stages of hemostasis
- primary
- secondary
- fibrinolysis
goal of hemostasis
patient doesn’t bleed or form systemic clots
what happens when capillaries are injured?
seal directly
lack a vessel wall and collagen fibers; no coagulation
structure of the blood vessel from inside to outside
- endothelial cells
- subendothelium, contains elastic tissues and collagen
- smooth muscle cells, allowing constriction/dilation
role of the blood vessel wall in clot formation
- vasoconstriction
- collagen exposure
- ADP release
- tissue factor release
released by platelets and contribute to vasoconstriction
serotonin
TXA2
2 functions of vasoconstriction
- decrease blood loss
- increase local concentration of procoagulants
function of ADP
released from endothelial damage
activates plts
if a lot of TF is released…
coag factors can all be used, leading to DIC
4 functions of plts
- fill small gaps between endothelial cells (maintains vascular integrity)
- formation of primary plt plug
- provides surface for fibrin generation (phospholipids)
- release PDGF to heal injured vessels
4 steps of primary plt plug formation
- vasoconstriction
- adhesion
- aggregation
- consolidation
explain linkages in adhesion and aggregation
adhesion = [collagen of subendothelium + vWF + GPIb/IX on plt]
aggregation = [GPIIb/IIIa + fibrinogen + GPIIb/IIIa]
adhesion causes plts to release…
ADP, which activates more plts
what happens to plts when they are activated?
shape change
discoid → spiny sphere
Ca is required
agents that induce plt activation
plt agonists
collagen
thrombin
ADP
TXA2
if stimulus from plt agonists is weak…
plts return to their original shape
platelet ——— is reversible if the stimulus by agonists is weak, but becomes irreversible after…
aggregation
plts degranulate (requiring Ca)
Ca released during aggregation activates the microfilament ————-
thrombasthenin
thrombasthenin results in…
exposure of PF3 on plts membrane
consolidation
tightening of plt plug
consolidation
function of consolidation
decreases plug permeability
