Flashcards in Primary Hemostasis Deck (49)
What are the hallmarks of primary hemostasis?
formation of weak platelet plug
What is the goal of secondary hemostasis?
stabilization of platelet plug (mediated by coagulation cascade)
What is step one of damaged vessels?
transient vasoconstriction (knee jerk reaction to pull away)
What mediates step 1 (vasoconstriction)?
1) neural reflex
2) endothelial cells themselves secrete endothelin
What is von willebrand's factor?
a factor that will come line the break down
What allows for VWF to bind?
What is the function of VWF?
to serve as a linker to bind to platelets
Where does VWF come from?
2) endothelial cells (most important)
What holds VWF in the endothelial cell?
Wiebold pilate body
(WP - P reminds that most important is P selectin and W reminds of VWF)
What is step 3?
shape change in platelets that allows for dumping of mediators (ADP and thromboxane A2 TXA2)
TXA2 is a derivative of _________________
What is essential for platelet aggregation?
GP2b3a (glycoprotein 2b3a)
What is essential for the expression of GP2b3a?
What is the role of TXA2?
to further recruit platelets to aggregate
What is the important linker molecule between Gp2b3a and platelets?
platelet aggregation occurs via ________ using ___________ as a linker
binding of VWF to exposed collagen (and then platelets bind to VWF)
What receptor do platelets use to bind to VWF?
What promotes exposure of GpIIb/IIIa?
What are the classical signs and symptoms of primary hemostasis disorders?
mucosal or skin bleeding
What are examples of mucosal bleeding?
epistaxis (nose bleeding)
hemoptysis (coughing up blood)
What is the feared complication of a low platelet count?
What are examples of skin bleeding?
Petechiae are a sign of ______________
thrombocytopenia (few platelets not a qualitative problem)
What is a normal platelet count?
What produces platelets?
megakaryocytes in the bone marrow
What is ITP?
autoimmune disorder where you produce IgG against platelet antigens (like GPIIb/IIIa)
What is the most common cause of thrombocytopenia?
What produces those autoantibodies in ITP?
plasma cells in the spleen
macrophages in the spleen also consume the platelets that are bound to the antibody