Coagulation Flashcards
what is PT? what coag factors is it associated with?
pro-time/prothrombin time test: this measures the extrinsic pathway (how quickly your blood clots)
-coag factors: VII, X, V, II, I
what is the path of the extrinsic pathway?
tissue factor –> VII –> X –> V –> II (prothrombin activator: prothrombin to thrombin) –> I (fibrinogen to fibrin)…
most of the coag factors are _____ synthesized ____
proteins, liver
5 stages of hemostasis
- vessel spasm 2. formation of platelet plug 3. blood coag (insoluble fibrin clot formed) 4. clot retraction 5. clot dissolution
(spasm, primary and secondary hemostasis)
INR is what?
international normalized ratio: measures how well an anticoagulation medicine is working.
= PT patient / PT normal population
PTT is what? associated with what factors?
partial thromboplastin time (w/ PT, asses amount and function of clotting factors). Intrinsic pathway efficiency. Factors XII, XI, IX, VIII, X, V, II, I
what is the path of the intrinsic path?
XII –> XI –> IX –> VIII –>X –> V –> II (prothrombin activator: prothrombin to thrombin) –> I (fibrinogen to fibrin)…
what is a normal PT?
12.5-15.0
long bleeding time = ____ count
decreased platelet FUNCTION
normal platelet count
150,000 - 400,000
ristocetin cofactor activity
RcoF is the most sensitive and specific test for von Willebrand’s disease (tests binding of vWF to platelet glycoprotein, and is decreased in virtually all types of the disease
what enzyme turns fibrinogen to insoluble fibrin (I) ?
thrombin
what enzyme turns prothrombin (II) into thrombin?
prothrombin activator (from factor X and V)
what is the thrombin time test? (TT) what would it be affected by?
TT: how fast thrombin can convert fibrinogen to fibrin
-affected by the level and/or function of fibrinogen and the presence of inhibitors (e.g., heparin, fibrinogen/fibrin degradation products, direct thrombin inhibitor).
what is a D-Dimer and what does it’s presence tell you?
D-Dimer (2 D fragments of a fibrin joined by a crosslink) is a fibrin degradation/split product (FDP or FSP) - a small fragment present in the blood after a clot is degraded by fibrinolysis. *Presence used to help Dx Thrombosis (DVT) (endothelial damage).
*(NEGATIVE result will rule OUT thrombosis)
what two tests measure kidney function? decreased kidney function will cause what?
BUN and creatinine : both metabolic products excreted in urine
Decrease intrinsic kidney function or blood profusion to the kidney will cause varying elevation in their values in the blood.
what is thrombogenicity? normal endothelium is ____
tendency to produce a thrombus (clot)
non-thrombogenic
how do resting platelets in endothelium remain unclotted?
- healthy endothelium release prostocyclin into plasma
- prostocyclin –> binds platelet membrane receptors = cAMP synthesis
- cAMP inhibits 2B3A, inhibits release of platelet aggregation agents or Ca2+.
what is 2B3A?
activated platelets express this to allow fibrinogen to cross bridge
what is BUN? its normal level?
blood urea nitrogen .
normal level: 6-20 mg/dL
what is creatinine? normal level?
is derived from the metabolism of creatine in muscle. Normal Values 0.6-1.2 mg/dl.
what is the process of primary hemostasis?
- Platelets adhere to vWF
- Shape change
- Granule release: Platelets become activated; secrete ADP and thromboxane (TXa2)
- Recruitment: further platelet activation
- aggregation: plug formed
Platelets have receptor for ADP; self-activating/aggregating
Occurring at the same time as primary platelet plug formation is _____, which refers to the activation of the _______
secondary hemostasis
coagulation cascade: reinforces platelet plug into stable secondary plug
in vivo the _____ is responsible for coagulation
the extrinsic pathway