Hemostasis and Thrombosis Flashcards
What are the 3 main players of hemostasis?
- vasoconstriction
- platelet plug
- blood clot
What are the function of platelets?
Primary hemostasis
lifespan: 8-12 days, eliminated via spleen
NEVER touch endothelium
What is the role of the endothelium?
Major intiator and regulator of coagulation cascade (AKA secondary hemostasis)
What types of proteins are secreted by the endothelium?
**1. **antithrombotic (antiplatelet, anticoagulation, fibrinolytic)
2. prothrombotic (vWF, TF/factor III, plasminogen activator inhibitors)
3. vascular repair (growth factors)
What are the steps of platelets in coagulation?
1. adhesion
(Gp1b - vWF)
2. activation
(release of ADP and TxA2, plug formation and secondary HS start)
3. secretion
(granules release contents, mesh forms)
**4. clot formation **
What are the important components of platelets?
granules
alpha (releases big mlcls like PDGF, clot factors)
dense (small mlcls like serotonin, Ca2+, ADP/ATP)
receptors
adrenaline, ADP, collagen, thrombin
GpIb - vWF
GpIIb/IIIa - fibrinogen (Factor I)
What diseases are related to abnormalities of hemostasis and thrombosis?
thrombocytopenia (decr. platelets)
DIC (incr. platelet CONSUMPTION)
Vit K deficiency (no activation)
Hepatic failure (factors made by liver)
Hemophilia (males only)
What is a zymogen and which factors are?
Inactive protein in bloodstream
Factors II (prothrombin), VII, IX (PTC), X (Stuart factor), XI, XII
~200 aas @ C-term w/ active site
9-12 Glu @ N-term bind Ca2+
Factors to know by name
I: fibrinogen
Ia: fibrin
II: prothrombin
IIa: thrombin
VIII: antihemophilic factor (AHF)
IX: plasma thrombplastin component (PTC)
X: Stuart factor
What are the overall steps of coagulation cascade?
- zymogens -> active enzymes via proteolysis
- complex formation w/ Ca2+, phospholipid surface, cofactors
- fibrinogen –thrombin–> fibrin monomer
- fibrin monomer -> crosslinked fibrin
- forms glue for platelet plug
What are the non-protein factors involved in the coagulation cascade?
Ca2+ (except in XII and XI)
Vitamin K
What is the aPTT test?
Activated Partial Thromboplastin Time for intrinsic pathway
HEPARIN
~25-35 s
> 35s; any factor deficiency (not VII)
What is the PT test?
Prothrombin Time for extrinsic pathway
WARFARIN
~11-15 s
> 15s; VII, X, V, II, I deficiency
What drugs increase coagulation times?
Dextran, indomethacin, salicylates, anticoagulants
