Pathoma TidBits Flashcards
What factors lead to tumor invasion
Downregulation of E-cadherin leads to dissociation, attachment to laminin destroys basement membrane, attachment to fibronectin leads to local spread
What is the first step of primary hemostasis? What is it triggered by?
Transient vasoconstriction, by neural stimulation and endothelin release from endothelial cells
Through what receptor does platelet adhesion occur? Aggregation?
adhesion to vWF= GP1b. Aggregation: GPIIb/IIIa
What two mediators do platelets release after binding to vWF?
ADP- promotes GPIIb/IIIa receptor exposure and TXA2 (COX derivative) to promote aggregation
What’s the presentation of a patient with primary hemostasis disorder? When would you see petechiae?
Mucosal and skin bleeding: epistaxis, hemoptysis, GI, hematuria, menorrhagia; Quantitative disorders, not qualitative
ITP is an autoimmune antibody against what?
IgG against GPIIb/IIa from plasma cells in spleen
What are the lab findings in ITP: count, PT/PTT, cells
Low platelets, normal PT/PTT, inc megakaryocytes (from inc platelet production)
What is caused by TTP? Where are thrombi common?
Autoantibody against ADAMS13 (divides multipers to monomers for degradation) leads to abnormal platelet adhesion; CNS
How does HUS lead to platelet microthrombi?
E Coli 0157:H7’s verotoxin damages endothelial cells
What are the labs in TTP/HUS: platelet count, bleeding time, PT/PTT,?
Thrombocytopenia, inc bleeding time, normal PT/PTT, anemia with schistocytes and megakaryocytes
What is the effect of aspirin and uremia on platelets?
Aspirin, blocks COX, leads to no TXA2: platelet aggregation; uremia: adhesion and aggregation
What’s the genetic GP1b def? What’s the important feature? GPIIb/IIIa def?
GP1b= Bernard-Soulier (big platelets); GPIIb/IIIa= Glanzmann
How do secondary hemostasis disorders present generally?
Deep tissue bleeding into muscles and joints; re-bleeding after surgery
Draw the coagulation cascade
INT: 12, 11, 9, 8. Ex: 7. Common: 10, 5, 2, 1.
What activates each pathway? How is it measured?
Intrinsic: subendothelial collagen, PTT. Extrinsic: PT, tissue thromboplastin