Pathoma: Primary Hemostasis and Related Bleeding Disorders Flashcards
The platelet plug is relatively _______.
weak
The very first step of primary hemostasis is _________.
vasoconstriction
What is vasoconstriction mediated by?
It is (1) a neural reflex and (2) a result of released endothelin
After vasoconstriction, the next step is __________.
von Willebrand factor to bind to collagen
Platelets bind von Willebrand through _________.
GPIb
von Willebrand factor is held within _________.
Weibel-Palade bodies
What is the first step that activates platelets?
Binding to vWF
Activated platelets release _________, which activate __________.
thromboxane A2 and ADP; other platelets, causing them to express GPIIb/IIIa
There are _________ and __________ platelet disorders.
qualitative; quantitative
Clinically, patients with disorders of primary hemostasis present with _________.
easy bruising, mucosal bleeding, and skin bleeding
The feared complication of thrombocytopenia is ___________.
intracranial bleeding
Explain the cellular biology of immunogenic thrombocytopenia.
Patients develop IgG against GPIIb/IIIa and the splenic macrophages destroy the platelets
IgG can actually cross the ____________.
placenta, so women with chronic ITP can have thrombocytopenic infants
Other than eliminating the troublesome macrophages, what does splenectomy accomplish?
It also removes some of the plasma cells that are producing anti-platelet antibody.
In addition to producing schistocytes, microangiopathic hemolytic anemia also leads to ____________.
thrombocytopenia due to platelet consumption
The two kinds of microangiopathic hemolytic anemia are ___________.
thrombotic thrombocytopenic purpura and hemolytic uremic syndrome
What enzyme is deficient in TTP (thrombotic thrombocytopenic purpura)?
ADAMSTS13; this enzyme breaks down vWF multimers; without it, vWF remains active, platelets adhere, and lots of little thrombi form.
What bacteria causes HUS?
Eschericia coli 0157:H7; it produces verotoxin that damages the endothelial cells, leading to similar symptoms of TTP
Where does E. coli 0157:H7 come from?
Undercooked beef
Other than thrombocytopenia, what are symptoms of microangiopathic hemolytic anemia?
Fever, renal insufficiency, and CNS abnormalities
In those with microangiopathic hemolytic anemia, what PTT/PT pattern will you see?
Normal!
Bernard-Soulier results from __________.
genetic defects in GP1b
Genetic defect of GPIIb/IIIa is called _________.
Glanzmann thrombasthenia
