Hemostatsis/Coag Cascade Flashcards
Phases of Hematostatsis
Primary Hematostasis
Secondary Hemostatsis- coagulation phase
Termination of coag rxns
fibrinolysis
result of primary hemostatsis
platelet plug formation
result of secondary hemostatsis
fibrin formation/stabilization
vascular injury exposes
subendothelium (procoagulant)
first step of primary hemostasis
vasoconstriction
formation of platelet plug requires
vWF
platelets
fibrinogen
where is vwf synthesized
endothelial cells
megakaryocytes
what is vwf stored as large multimers in
weibel-palade bodies in endothelum
alpha granules in plasma cells
lifespan of a platelet
7-10 days
where is fibrinogen made
liver
3 categories of alpha granules
adhesive proteins
coagulant proteins
growth factors, selectins
adhesive proteins
fibronectin
vWF
coagulant proteins
fibrinogen
factor V
growth factors, selectins
PDGF, VEGF
P-selectin
dense
adp
atp
serotonin
calcium
Thromboxane A2
more vasoconstriction
platelet agg
platelet activation
fibrinogen binds to platelet via
GpIIb/IIIa R
platelet factor 3 activity
exposure of PS and PE on platelet surface allows coag factors to bind to platelets
secondary hemostasis is required to form
thrombus
fibrin
forms a mesh around platelets, stabilizes the platelet plus while blood vessel heals
coagulation factors circulate as
inactive (zymogen) as well as active forms
which factors are not synthesized by liver
Factor VIIII
vWF
what is factor VIII synthesized by
liver
vascular endothelium
dep on vit K for fx
2,7,9,10,S,C,Z
protein S, C, & Z are
endogenous anticoagulant factors
tissue factor
monocytes circulate in resting state and are stimulated by vascular injury to produce TF– physiological
TF forms a complex w/ circulating factor VII
activation of factor VII to VIIa
factor Ix requires
Ca and factor 8 as cofactor to bind to platelet membrane phospholipid
–accelerates activation of factor X to Xa by 100,00 fold
factor 2
prothrombin
factor 2a
thrombin
prothrombinase complex
factor Va anchors factor 10a and prothrombin (2) in close proximity on platelet phospholipid
thrombin burst
small amount of thombin feeds back and activates XI to XIa by catalyzing 9-9a and 10-10a, etc
clotting functions of thrombin
hydrolyzes fibrinogen to form fibrin involved in many feedback activities activates factor 8 to stabilize fibrin protects established clot (thrombus) from fibrinolysis inhibits coag when needed
controlling coagulation
-hemodillution
hepatic clearance
endogenous anticoags
fibrinolysis (plasmin)
Antithrombin
produced by liver, endothelial cells
binds and inhibits factor Xa and thrombin
heparin
increases anticoag activity of AT
activated protein C
thrombin binds thrombomodulin on endothelial cell surface changing its structure–> can now activate proten C but not others
APC + S–>inactivates factors Va and VIIIa
tissue factor pathway inhibitor
produced by endothelial cells
binds to and activates factor Xa
inactivates TF/VIIa complex
plasminogen
synthesized by liver and circulates–> binds to fibrin–>cleaved to plasmin
plasmin cleaves
fibrin–>D dimers
PAI-1
stored n platlets; inhibits tPA
alpha 2 antiplasmin
major inhibitor of plasmin
plasma
fluid fraction of unclotted, whole blood
contains all soluble components including coag factors, fibrinogen, etc
serum
fluid remaining after blood has been allowed to clot; contains all soluble components except for coag factors
coag factors are performed with
plasma
citrate
anticoag for coagulation tests
binds Ca making ti unavailable for coagulation reactions
bleeding time
measures primary hemostasis
PFA-100
measures how long it takes for platelets to clot
PT
time required to form fibrin clot when citrated patient plasma is added to thromboplastin Ca mixture
measures extrinsic
PT normal time
12.2-14.8
INR
standardizes PT
=patient PT/mean PT
normal=1
anticoag=2-3
aPTT
activated partial thromboplastin time; not natural- lab driven
time required to form fibrin clot when citrated patient plasma is added to PHOSPHOLIPID+ Ca+ contact activator
contact activators
glass
kaolin
celiate
ellagic acid
aPTT is prolonged with
issues in the common and intrinsic pathways
prolonged PT could mean
mild liver disease
early vitamin K def
early warfarin
factor 7 issue
prolonged aPTT could mean
hemostatic factor dysfunction (hemophilia)
vWF disease
heparin
prolonged PT and PTT
severe liver disease consumptive coagulopathy hemodilution severe vitamin K def therapeutic warfarin hypofibrinogenemia/dysfibrinogenemia direct thrombin inhibitors
therapeutic warfarin inhibits factors
2,7,9,10
mixing studies and inhibitor
doesnt fix clotting
mixing study and factor def
fixes clotting
how does thrombin clotting time test work
exogenous thrombin + patient plasma
thrombin time prolonged in
hypofibrinogenemia
dysfibrinogenemia
heparin, thombin inhibitors
what does thrombin clotting time detect
fibrinogen abnormalities
D-dimer is a maker of
clot formation/breakdown
three ways to get a quantitative thrombocytopenia
increased destruction
sequestration in spleen
decreased production
what does heparin do to platelets?
low platelets, but no bleeding– paradoxical state of hypercoagulation
8 ways to get destruction/consumption of platelets
autoimmune mediated processes medications DIC TTP HELLP syndrome in pregnancy HUS severe bleeding vWF, type 2b
enlarged spleen can hold up to
90% of platlets
enlarged spleen vs normal spleen and platelets
normal spleen- can hold 30%
enlarged spleen- 90%
come causes of splenmegaly and platelet sequestration
portal htn (hepatic cirrhosis, thrombosis of portal or hepatic vein) myeloproliferative diseases
decrease in production of platelets (6)
primary bone marrow disorders (leukemia, aplastic anemia, etc) bone marrow infiltrative process viral infections (hep, hiv) toxic exposures to megakaryocytes nutritional deficiencies hereditary disorders
6 categories of hereditary qualitative disorders
bernard-soulier glanzmann thromboasthenia storage disorders delta granule disorders signal transduction disorders (decrease in release of granules) scott syndrome
berniar soluier disease
defect in GP1B R
Glanzzmann Thrombasthenia
defect in GPIIb/IIIa R
storage disorders
gray platelet syndrome (absent alpha granules)
quebec platelet syndrome (inc uPa in alpha granules so they are degraded)
delta granule disorders
decrease in release of ADP due to hermansky pudak, chediak-higashi syndrome
scott syndrome
defect in assembly on platlet surface
8 ways to get aquired qualitative platelet disorders
aspirin nsaid gpIIb/IIIa inhibitors ADP R inhibitors SSRI Herbal uremia myeloproflierative disorders
aspirin
irreversibly acetylates cyclooxygenase–>results in inhibition of thromboxane A2 production
GPIIb/IIIA inhibitor
abciximab
ADP R inhibiors
clopidogrel
prasurgel