Hemostasis

Question 1

What causes vasoconstriction in hemostasis and where does it come from?

Answer 1

Endothelin released by endothelial cells (via damage)

Question 2

What happens in primary hemostasis?

Answer 2

platelets adhere via vWF and aggregation

Question 3

What happens in secondary hemostasis?

what holds everything together?

Answer 3

local activation of coagulation cascade by TF and phospholipids –> fibrin formation
- held together via Ca bonds

Question 4

What do platelets contain?

Answer 4

• Alpha granules (purple = fibrinogen, vWF, PDGF)
• dense granules (serotonin, ADP, calcium)
• contractile proteins

Question 5

What causes adherence in hemostasis?

Answer 5

Gp1b and vWF

Question 6

What causes aggregation in hemostasis?

Answer 6

ADP/TXA2

via GpIIb/IIIa and fibrinogen

Question 7

What is vWF cleaved by?

Answer 7

ADAMTS13

Question 8

vWF carries what factor?

Answer 8

factor 8

Question 9

Bernard Soulier Syndrome

Answer 9

Lack of GPIb and no response to ristocetin

• no interaction with vWF so no binding
• giant platelets and thrombocytopenia possible

Question 10

Glanzmann Thrombasthenia

Answer 10

Autosomal Recessive

• no GpIIb and GpIIIa
• unable to bind fibrinogen –> no aggregation/crosslink
• only responds slightly to ristocetin

Question 11

Dense Granule Disorder (platelet disorder)

Answer 11

gray platelets seen

- Chediak Higashi (mutated CHS1 gene) and Hermansky Pudlak (albino/PR)

Question 12

Action of Thrombin

Answer 12

convert fibrinogen to fibrin

Question 13

Which factors are vitamin K dependent?

shortest 1/2 life?

Answer 13

2, 7, 9, 10

shortest= 7

Question 14

Which factor has the longest half life

Answer 14

13

Question 15

What test checks the extrinsic pathway and common pathway?

what does it also monitor

Answer 15

PT

• also used to monitor warfarin

Question 16

What factors are in the extrinsic pathway?

Answer 16

3+7 = 10

3 is turned off via TFPI

Question 17

What factors are in the intrinsic pathway?

Answer 17

12, 11, 9, 8 = 10

Question 18

Common pathway factors

Answer 18

“bills beneath 20”

10,5,2,1

Question 19

aPTT

definition and monitors what

Answer 19

activated partial thromboplastin time

• looking for deficiency in clotting factors of intrinsic and common pathway
• also monitors heparin

Question 20

If PT or PTT is prolonged, what do you check next?

Answer 20

1: 1 Mix of patient plasma and control plasma
- issue with def = will correct
- issue with inhibitor = will not correct
- Factor 8 is time dependent

Question 21

Thrombin time

Answer 21

tests end of cascade

- if increased: fibrinogen def, fibrin degradation products, heparin

Question 22

Antithrombotic regulation

Answer 22

Release of tPA and thrombomodulin

Question 23

Tissue factor pathway inhibitor

Answer 23

stops extrinsic pathway (factor 3)

Question 24

Protein C

Answer 24

serine protease that degrades factor 5 and 8

- vitamin K dep

Question 25

Heparin mechanism of action

What happens when the target is deficient?

Answer 25

Antithrombin

if deficient in Antithrombin III = won’t respond –> issues with all pathways

Question 26

direct thrombin inhibitor

Answer 26

dabigatran

prevents clotting

Question 27

oral factor 10 inhibitor

Answer 27

Rivoroxaban and Apixaban