Bleeding and hemostasis Flashcards
(19 cards)
Primary hemostasis?
Platelets and sub-endothelial collagen react to form a platelet plug
Secondary hemostasis?
Coagulation factors react to form fibrin polymers that stabilize the platelet plug (from primary) to form a mature thrombus
Fibrinolysis
dissolution of the fibrin clot
Platelets
From megakaryocyte in BM
Release at about 10 to the 11 per day
Live about 6-8 days
When activated makes TxA2 cox-1 mediated. Major platelet aggregation factor
Platelet adherence to sub endo collagen - via…
platelet glycoprotein VI receptor or
vWf via glycoprotein Ib receptor
3 overlapping phases of cell based model of coagulation
Initiation, amplification, propagation
What cell(s) involved with initiation?
Tissue factor (TF) bearing cells
What coagulation factors are involved with initiation?
7, TF, 10, 9, 5, and a small amount of 2a(thrombin)
Whats the end result of initiation?
Small amount of thrombin (2a) is formed which activates local platelets
Activated factor 9 (9a) is released
What cell(s) involved with amplification?
Platelets
What coagulation factors are involved with amplification
2,5,8,
Whats the end result of amplification
activated platelet with 5a and 8a attached
What cell(s) involved with propagation
activated platelet
Whats end result of propagation
Lots of thrombin
2 places thrombin is formed
Small amount on TF bearing cells
Large amount on activated platelets
Thrombin activities
activates - platelets, factors 5, 8 (cleaving off vWf in the process), 11, cleaves fibrinogen to fibrin
TF/VIIa complex: where is it and whats it do?
on TF bearing cells and activates 9 and 10
9a/8a
on activated platelets and activates 10
10a/5a
on TF bearing cells and activated platelets
Cleaves prothrombin to thrombin
