Hemostasis Flashcards
-Normal Hemostasis -Laboratory Evaluation
What are the 3 steps of normal hemostasis?
- Vasoconstriction
- Platelet aggregation
- Fibrin formation
What platelet antigen is the receptor for collagen?
GPIa/IIa complex
What platelet antigen is the receptor for vWF?
GPIb
How is GPIb activated (in vivo/in vitro)?
- Shear forces (in vivo)
- Ristocetin (in vitro)
Platelet degranulation leads to release of what?
- alpha and dense granules
- Thromboxane A2 (TXA2)
What do platelet Alpha granules contain? (5)
Large molecules:
- fibrinogen
- PDGF
- vWF
- P-selectin
- Platelet Factor 4 (PF4)
What do platelet Dense granules contain? (4)
Small molecules:
- ADP
- ATP
- 5-HT
- Calcium
What stimulates platelet degranulation? (6)
Platelet Agonists:
- Epinephrine
- ADP
- Thrombin
- Platelet Activating Factor
- Collagen
- TXA2
What mediates platelet aggregation? (2)
- GPIIb/IIIa
- Fibrinogen
Factors in Intrinsic Pathway.
- Factors 12,11,9,8
- prekallikrein & HMWK
Which factor links Intrinsic and Extrinsic Pathways?
Factor 10a
-F7 to F7a
What is the only factor unique to the Extrinsic pathway?
-F7
What initiates Extrinsic Pathway in vitro?
Tissue Factor (Factor 3)
What does activated factor 7 (F7a) do?
Cleaves F10 to F10a
F7a is the “tenase” of the Extrinsic Pathway
What are the constituents of the Common Pathway?
- F10
- Prothrombin (F2)
- Fibrinogen (F1)
What initiates the Common Pathway?
Activation of F10 to F10a
What does F10a do?
Converts F2 to F2a (thrombin)
What platelet cell surface antigen is the receptor for vWF?
GpIb/V/IX complex (CD42)
What Red Cell antigens are also on platelet cell surface? (5)
- ABO
- P
- I/i
- Le
*NO Rh antigens
Which MHC class antigens are present on platelet cell surface?
MHC Class I
Which clotting factor has the shortest T1/2?
Factor 7 (FVII) -6 hours
Vitamin K dependent coagulation factors. (4)
-2,7,9,10 (II,VII,IX,X)
