5-29 GOUELI Coag Biochem

Question 1

What is a normal platelet count?

Answer 1

150,000 – 450,000 platelets/uL

Question 2

Define hemostasis?

Answer 2

Physiological blood clotting in response to injury.

Question 3

Define Thrombosis?

Answer 3

Pathologic blood clotting

Question 4

Define Hemorrhage?

Answer 4

Pathologic bleeding

Question 5

What is the overview, big picture of how hemostasis works?

Answer 5

1) Vasoconstriction in response to injury
2) Platelet plug (Primary Hemostasis)
3) Fibrin plug (clot) (Secondary Hemostasis)
4) Clot dissolves (Anti-coagulants / fibrinolytics)

Question 6

What are the 3 fundamental mechanisms in PRIMARY HEMOSTASIS?

Answer 6

Adhesion – platelets adhere to exposed collagen
Aggregation
Secretion (of platelet granule contents)

Question 7

What coagulation factor does vWF stablilize?

Answer 7

Factor VIII

Question 8

What does GP Ib bind?

Answer 8

vWF

Question 9

What does GP VI bind?

Answer 9

Collagen

Question 10

What does GP IIa-IIIb bind?

Answer 10

Other platelets via vWF/fibrinogen

Question 11

What is ADP’s role in platelet aggregation?

Answer 11

ADP released from platelet granules -> binds platelet ADP-receptors -> activates platelets -> unmasks Gp IIb-IIIa

Question 12

What is Plavix?

Answer 12

ADP-receptor antagonist -> ↓clot formation

Question 13

If you admit someone for MI, what must you put them on?

Answer 13

Aspirin. Otherwise it’s malpractice

Question 14

What is secondary hemostasis? What are the broad steps involved?

Answer 14

Secondary Hemostasis is formation of the FIBRIN PLUG (clot)
2 pathways (INTRINSIC, and EXTRINSIC) converge to common path
OVERARCHING GOAL is producing fibrin!

Question 15

What is the “additional substance” necessary for the extrinsic pathway?

Answer 15

Tissue factor

Question 16

Where does Tissue Factor come from?

Answer 16

Not plasma

Surface protein expressed on endothelial cells exposed to cytokines

Question 17

Where do the clotting factors (eg Factor VIII, Factor IX) come from?

Answer 17

Synthesized by liver (as zymogens)

Question 18

What is the role of phospholipids in the activation of zymogens?

Answer 18

Surface of activated platelets kinda flip.
This surface provides an area where zymogens can be enzymatically
cleaved to form activated factors (eg Factor VIIIa)

Question 19

Will a patient with Factor XII deficiency have any symptoms? Why?

Answer 19

No b/c that part of the pathway can be activated by many things, including thrombin

Question 20

What does heparin do?

Answer 20

Activates ATIII

Question 21

What anticoagulant does Coumadin also antagonize? What are the implications?

Answer 21

Protein C and S activity also decreases from Coumadin.
Thus, admin of Coumadin to patient INITALLY causes HYPERcoag!
Thus, we BRIDGE W/HEPARIN