Flashcards in Hemostasis: Pathoma Deck (59):
What is hemostasis
Repair to damaged blood vessels through formation of a clot/thrombus
Hemostasis occurs in what stages?
Primary hemostasis forms what?
What mediates this?
Weak platelet plug
Interaction between platelets and vessel wall
Secondary hemostasis has what effect?
4 steps of primary hemostasis
1. Transient vasoconstriction of BV
2. Platelet adhesion
3. Platelet degranulation
4. Platelet aggregation
What mediates transient vasoconstriction of BV?
Reflex neural stimulation
Endotheli release from endothelial cells
How do platelets adhere to surface of damaged BV? 2
1. vWF binds to exposed collagen
2. Platelets bind to vWF using GPIb receptor
vWF is derived from what two locations?
1. Weibel-Palade bodies of endothelial cells
2. Alpha granules of platelets
In platelet degranulation, what is released? 2
1. ADP from platelet dense granules
2. TXA2 from platelet COX enzyme
ADP has what effect?
Promotes exposure of GPIIb/IIIa receptor on platelets
TXA2 has what funciton?
Promotes platelet aggregation
Platelet aggregation occurs how?
Platelets aggregate at site of injury via GPIIb/IIIa using fibrinogen as a linking molecule
Disorders of primary hemostasis are due to what?
Qualitative or quantitative changes to platelets
2 sets of clinical features of primary hemostasis
Most common skin bleeding symptom in primary hemostasis disorder?
Most feared complication of mucosal bleeding?
4 useful platelet counts in determining disorders?
1. Platelet count
2. Bleeding time
3. Blood smear
4. Bone marrow biopsy
Immune thrombocytopenic purpura definition
Autoimmune production of IgG against platelet antigens
Who makes the antibodies in ITP?
What eats the antibody-bound platelets?
Acute form of TPP is in what age?
Chronic ITP is in what age?
What happens if pregnant woman gets ITP?
Fetus will get some anti-platelet Ab's that will cross placenta and have effects for awhile.
Lab findings in ITP? 3
1. Decrease platelet count
2. normal PT/PTT
3. Increase in megakaryocytes in BM biopsy
First Treatment of ITP?
Secondary treatment of ITP?
1. IVIG to raise platelet count
2. Splenectomy to remove source of Ab's and platelet destruction
Microangiopathic hemolytic anemia results in formation of what?
Platelet microthrombi in small vessels
MHA has what effect on platelets and RBC's
RBC's are sheared resulting in hemolytic anemia with schistocytes
Two causes of MHA?
Thrombotic thrombocytopenic purpura
Hemolytic Uremic syndrome
TTP is due to what?
Auto Antibodies against the enzyme ADAMS13 which results in large polymers of vWF causing abnormal platelet adhesion and microthrombi
TTP common population?
HUS is due to what?
Endothelial damage by drugs or infection causing platelet microthrombi to form
E. coli O157:H7 verotoxin
Clinical findings of both MHA's?
1. Skiin and mucosal bleeding
2. Hemolytic anemia
4. Renal insufficiency (HUS)
5. CNS problems (tTP)
Lab findings in both MHA's? 5
2. Increased bleeding time
3. Normal PT/PTT
4. Anemia with schistocytes
5. Increase in megakaryocytes
Treatments of hemostasis? 2
Plasmapheresis and corticosteroids
Bernard Soulier syndrome is a genetic deficiency in what?
Platelet adhesion impaired
Glanzmann thrombasthenia is due to what?
What is result
Genetic GPIIb/IIIa deficiency
Platelet aggregation impaired
Aspirin's effect on platelets?
Inhibits COX --> lack of TXA2 --> Impaired aggregation
Uremia effect on platelets?
Impairs platelet function --> Both adhesion and aggregation impaired
Purpose of secondary hemostasis?
Stabilize weak plug via the cogulation cascade
End product of coagulation cascade?
What does thrombin do?
Converts fibrinogen in the platelet plug to fibrin.
Function of fibrin?
Cross-link and yield a stable platelet fibrin thrombus
Coagulation factors are produced where?
Activation of coagulation factors requires what? (3)
1. Exposure to an activating substance
2. Phospholipid surface of platelets
Disorders of secondary hemostasis is usually due to what?
Clinical features of secondary hemostasis?
Deep tissue bleeding into muscles and joints
Rebleeding after surgical procedures
What is goal of both coag pathways?
Intrinsic factor pathway?
12, 11, 9, 8, 10
Extrinsic factor pathway?
What activates Factor 12 in intrinsic?
What activates Factor 7 in extrinsic?
PT measures what?
Extrinsic pathway (factor VII)
PTT measures what?
Intrinsic pathway (factors XII, XI, IX, VIII)
PTT measures what drug?
PT measures what drug?
Hemophilia A is defect in what?
Can you acquire the mutation?
Factor 8 deficiency
Lab findings in hemophilia A?
Platelet count and bleeding time
High PTT, normal PT
Decrease factor 8 in blood
Normal platelet count and bleeding time
Treatment of hemophilia A?
recombinant factor 8