assays for hemostasis Flashcards
(31 cards)
megakaryoctyes
develop from hemopoietic stem cells that reside in bone morrow
Meg-CFC (megokaryocyte colony simulating factor) then begin ____ in which the DNA replication continues but neither the nucleus nor the cell undergoes division this produces a ________ cell
endomitosis; polyploid
C-Mpl
TPO receptor on megokaryocytes and platelets; when TPO binds it increase platelet synthesis
TPO
thrombopoietin; stimulates platelet synthesis, made in the liver; static
phospholipid scaffold is important for
secondary coagulation factors
alpha2beta1
GP2GP3
binds collagen
alpha2bbeta3
GPIIbGPIIIa
binds fibrinogen
GP Ib- IX-V
binds von willebrand
GP VI
activates platelets by binding collagen
platelet plug formation (4)
- Adhesion
- Activation
- Aggregation
- Secretion
adhesion
GP Ib- IX-V binding to VWF
activation
platelets become activated and secrete GP IIB-IIIA
aggregation
GP IIb IIIa activates fibrinogen
secretion
platelets release granular contents and potentiate clotting
qualitative platelet disorders can be
congenital or acquired
acquired platelet disroders
- NSAIDS and aspirin
- herbs
- myeloproliferative disease
- uremia
congenital
- Bernards- GP Ib IX-V deficiency- lack of platelet adhesion
- Glanzmanns thrombaesthenia- GP IIb-IIIa deficiency- lack of aggregation
platelet dysfunction symptoms
- mucocutaneous bleeding
- same as primary hemostasis- epistaxis, gum bleeding, bruising, heavy menses, petechiae
how to quantify platelet disorders
PFA platelet function analyzer 100; bleeding time
what keeps platelets from sticking to normal endothelium?
- NO
- Prostacyclin
- ecto-ADPase- chews up ADP to prevent platelet activation
collagen
GP Ib IX-V
GP VI
thrombin
- most potent platelet agonist
- PAR-1 receptor bind thrombin
thromboxane
COX 1 activation leads to production of thromboxane
- thromboxane receptor is GPCR
ADP
- secreted by lysed RBC and activated platelets
- PY12 and PY1 receptors
- GPCR