Ch 4 Flashcards
Oedema in (location) is characteristic of severe renal failure.
Periorbital
Why is cyanosis/congestion blue?
Accumulation of deoxygenated Hb
What are the key steps in haemostasis (control of bleeding)? 4
- Reflex vasoconstriction (mediated by endothelin from endothelial cells)
- Primary haemostasis (endothelial vWF activates platelets)
- Secondary haemostasis (subendothelial TF bind to FVII to generate thrombin)
- Thrombus/antithrombotic events (fibrin and platelets form solid clot)
____ receptors form crosslinks with platelets and fibrinogen –> plt aggregation
GpIIb/IIIa
What is involved in platelet activation?
Platelets adhere –>activate –> secretion of calcium and ADP –> activation of GpIIa/IIIa receptors
How do platelets adhere to endothelium?
GpIb receptors bind to vWF
Coagulation: how is a definitive haemostatic plug formed?
Fibrinogen into fibrin (via Thrombin)
____ is the most important initiator of coagulation cascade
Tissue factor (TF)
What limit coagulation to site of injury? 3
- Initiation of cascade limited to platelets and endothelium at site of injury.
- Inhibitors antithrombin III, augmented by heparin like molecules expressed on endothelium.
- Fibrinolytic pathways eg t-PA with fibrin
Coagulation: what is the role of plasmin?
Breaks down fibrin
Fibrinolysis: What does t-PA do?
Generates plasmin (from plasminogen)
What 2 ways that plasmin can be generated?
- Plasminogen activators eg t-PA
- Factor XII pathway
What is Virchows triad?
1.Endoghelial injury
2. Blood stasis
3.Hypercoagulability
White vs red infarcts?
White: arterial occlusion in dense tissues eg spleen, liver, heart
Red: venous occlusion in loose spongy tissue eg testicles, lung
What are the lines of Zahn represent? White vs dark
White - coagulated fibrin and platelets
Dark - RBCs
