Hemostasis 2 Flashcards
What factor # is vWF?
VIII
Average half-life span of platelet
8-12 days
How does vWF work?
Anchors platelets to collagen layer of damaged subendothelium of vessel.
One end attaches to vessel wall , other end attaches to platelet
What is the most inherited coagulation defect?
Von Willebrand’s disease
When should you suspect Von Willebrand’s disease?
Suspect In any person with increased bleeding time despite normal platelet count and normal clot retraction.
What is the first line treatment for Von Willebrand’s disease?
DDAVP (desmopressin)
Causes release of endogenous stores of vWF.
What factors does cryoprecipitate have?
VIII (vWF)
I (fibrinogen)
XIII
- give to pts with Von Willebrand’s who are not responsive to DDAVP.
What 2 substances released from the activated platelet, stimulate platelet aggregation?
A2 and ADP
What clotting factor activates the platelet at the site of vascular injury?
Thrombin (factor IIa)
What substance links platelets together (aggregates them)?
Fibrinogen
What agents inhibit platelet aggregation by impairing cyclo-oxygenase?
Asprin - lifetime of the platelet
NSAIDS - impair for 24-48 hrs
What clotting factors are found in the extrinsic pathway?
III - thromboplastin
VII
“For .37 cents you can buy the extrinsic pathway”
What clotting factors are found in the intrinsic pathway?
XII, XI, IX, VIII
“If you can not buy the intrinsic pathway for $12, you can get it for $11.98”
What factors are found in the final common pathway?
X, V, II, I, XIII
“The final common pathway can be purchased at the five & dime (V, X), on the 13th (XIII) of the month for $1-$2 (I, II).”
What clotting factor is considered the physiologic initiator of the coagulation cascade?
III - Tissue factor or Thromboplastin
What clotting factor promotes fibrin cross-linking?
XIII - fibrin stabilizing factor
Antithrombin III inhibits what five clotting factors? Which of these is in the intrinsic pathway? What two of these are most profoundly inhibited?
- II, IX, X, XI, XII
- IX, XI, XII
- II, X
What four clotting factors are Vit K dependent? Which is in the extrinsic pathway?
- II, VII, IX, X
2. VII
How does heparin work?
heparin works by increasing antithrombin effectiveness by 1,000 fold or more
How does coumadin work?
Binds to Vit K receptor in liver and competatively inhibits Vit K which leads to Vit K dependent clotting factors being depressed
What anticoagulent affects the intrinsic and final common pathways?
Heparin
What 2 coagulation tests assess the extrinsic pathway?
PT, INR
What 2 coagulation tests assess the intrinsic pathway?
PTT, ACT
How does protamine work on heparin? What kind of reaction is this?
- Protamine (positively charged) binds with heparin (negatively charged).
- NEUTRALIZATION REACTION
