Vascular Disorders & Thrombosis 2 Flashcards
Physiologic response at the site of blood vessel injury to seal the injured vessel and prevent blood loss
Normal hemostasis
What are the three general components involved in hemostasis?
Platelets, clotting factors, endothelium
Hemostasis mediated by platelets
Primary hemostasis
Hemostasis mediated by clotting factors
Secondary hemostasis
What are the two possible outcomes of failed hemostasis?
Blood loss (hemorrhage) or inappropriate clot formation (thrombosis)
What is the purpose of arteriolar vasoconstriction in the hemostasis process?
To reduce blood flow to the injured area
What is the purpose of “primary hemostasis” in the hemostasis process?
To form the primary hemostatic plug
How do platelets respond to the exposure of subendothelial von Willebrand factor (vWF)?
(5 steps)
Through adhesion, shape change, granule release, recruitment, and aggregation
What is done during primary hemostatic coagulation testing?
- Blood smear evaluation and platelet count
- Buccal mucosal bleeding time (to see how long it takes for primary clot to form)
What is the purpose of “secondary hemostasis” in the hemostasis process?
To deposit fibrin and form a secondary hemostatic plug
(mediated by: the coagulation cascade)
What process does secondary hemostasis follow?
(4 steps)
- Tissue factor (TF) release
- Coagulation factor activation (involving TF and platelet phospholipid)
- Thrombin activation
- Fibrin polymerization
Which pathway is associated with coagulation factor VII?
Extrinsic
Which pathway is associated with coagulation factors XII, XI, IX, and X?
Intrinsic
Which pathway is associated with coagulation factors X, V, II, and I (fibrinogen)?
Common
What are the (4) vitamin K-dependent coagulation factors assessed during coagulation assays (PT, aPTT)?
II, VII, IX, and X