Hemostasis & Thrombosis Flashcards
cessation of blood flow from an injured blood vessel; maintaining blood in a fluid state
hemostasis
what are the 2 parts of primary hemostasis?
vasoconstriction
platelet activation
what are the 2 parts of secondary hemostasis?
coagulation cascade
antithrombotic control mechanisms
what occurs in primary hemostasis?
platelet plug formation
what occurs in secondary hemostasis?
formation of fibrin clot (thrombus)
what occurs during fibrinolysis of the hemostasis process?
plasmin breaks down fibrin clot, limits the size of the clot so it becomes normal tissue
what process is caused by proteins from activated PLTs and injured endothelial cells?
vasoconstriction
during primary hemostasis, damaged endothelial cells produce vWF, tissue factor, expose collagen, secrete plt-activating factor, and release plasminogen activator inhibitor to inhibit fibrinolysis. what is this process called?
thrombogenesis
what produces platelets?
megakaryocytes in bone marrow
what is the lifespan of platelets?
7-10 days
what are the 3 roles of platelets in primary hemostasis? (AAA)
adhesion
activation
aggregation
what acts as the glue for optimal platelet-collagen binding?
von Willebrand factor
how long does aspirin inhibit platelet function?
life of platelet
platelet recruiting and attachment to adjacent platelets to form a mesh network
aggregation
the PLT-PLT cross linkage is stabilized by what?
thrombospondin
in the coagulation cascade, which pathway overrides?
intrinsic pathway
anticoagulant protein that inhibits early phases of extrinsic response to neutralize factor VIIa
tissue factor pathway inhibitor (TFPI)
serine protease inhibitor made by the liver that binds thrombin and factor Xa, neutralizing their activity
anti-thrombin
what enhances anti-thrombin activity?
heparin released by endothelial cells
serine protease produced by the liver that degrades factors Va and VIIa
protein C
what does protein C depend on?
vitamin K
protein made by the liver, endothelial cells, and PLTs that serves as a cofactor to protein C activity to neutralize factors Va and VIIa
protein S
what does d-dimer find?
fibrin degradation products (FDP) that are still attached to factor XIII
what do defects in hemostasis result in?
abnormal bleeding or clotting
what are some examples of conditions that present with thrombocytosis? (5) HIMMS
Hemorrhage
Infection
Myeloproliferative disorder (MPD)
Malignancy
Splenectomy
what are some conditions that present with thrombocytopenia? (3) BAL
Bone marrow disorders
Autoimmune disease
Liver disease
pinpoint, flat and small, purplish spots
petechiae
red, dark blue localized to one area; do not blanch with pressure
purpura
what does generalized purpura indicate?
systemic problem (meningitis, lupus)
deep collections of blood under the skin that changes color
ecchymosis
what is the most common reason platelet function changes?
medications (aspirin or clopidogrel)
time required to build a stable platelet plug and obtain full occlusion, reported in seconds
closure time
when could closure time be abnormal?
if PLT count or HCT is low
measurement of PLT aggregation to various activators in vitro; recorded by a light transmission aggregometer
PLT aggregation studies
what is the gold standard in PLT function testing?
platelet aggregation studies
two incisions made and the time for clotting to occur is recorded
bleeding time
measures extrinsic and common pathways to evaluate liver function
prothrombin time (PT)
what is the method of choice to monitor coumadin (warfarin) therapy?
INR
what does an increase in INR indicate?
increased anticoagulation
measures intrinsic and common pathways to monitor heparin therapy and evaluate liver function
activated partial thromboplastin time (APTT)
measures conversion of fibrinogen to fibrin in common pathway and is sensitive to circulating anticoagulants like heparin
thrombin time (TT)
measures protein concentration, and is used in the diagnosis of hypo or dysfibrinogenemia, disseminated intravascular coagulation (DIC), and primary fibrinolysis
fibrinogen
what assay is most commonly performed for fibrinogen?
clauss assay
what do FDP cause in thrombin time test?
visible agglutination
what does a positive D-dimer indicate?
clot has formed and is breaking down
what are 4 conditions that cause high D-dimer levels? PMSH
pregnancy
surgery
malignancy
heart disease
inhibits carboxylation of vitamin K dependent coagulation factors (II, VII, IX, X)
MOA for warfarin
how long does warfarin take to reach therapeutic levels?
4-5 days
what do we use to monitor warfarin?
PT/INR
inhibits thrombin activation of platelets (thrombin, V, VIII, IXa, and Xa)
MOA of heparin
what do we use to monitor heparin?
APTT
what is a complication of heparin?
heparin-induced thrombocytopenia (HIT)
inactivates Xa but less effective in inactivating thrombin
LMW Heparin
what do we use to monitor LMWH?
factor Xa inhibition assay
