Hemostasis: Pathoma Flashcards
What is hemostasis
Repair to damaged blood vessels through formation of a clot/thrombus
Hemostasis occurs in what stages?
Primary
Secondary
Primary hemostasis forms what?
What mediates this?
Weak platelet plug
Interaction between platelets and vessel wall
Secondary hemostasis has what effect?
What mediates?
Platelet plug
Coagulation cascade
4 steps of primary hemostasis
- Transient vasoconstriction of BV
- Platelet adhesion
- Platelet degranulation
- 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
- vWF binds to exposed collagen
2. Platelets bind to vWF using GPIb receptor
vWF is derived from what two locations?
- Weibel-Palade bodies of endothelial cells
2. Alpha granules of platelets
In platelet degranulation, what is released? 2
- 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
Mucosal bleeding
Skin bleeding
Most common skin bleeding symptom in primary hemostasis disorder?
Epistaxis
Most feared complication of mucosal bleeding?
Intracranial bleeding
4 useful platelet counts in determining disorders?
- Platelet count
- Bleeding time
- Blood smear
- 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?
Spleen
Spleen
Acute form of TPP is in what age?
Kids
Chronic ITP is in what age?
Adults
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
- Decrease platelet count
- normal PT/PTT
- Increase in megakaryocytes in BM biopsy