platelet function:
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platelet function: - PowerPoint PPT PresentationTRANSCRIPT
platelet function: 1- Adhesion — the deposition of platelets on the . subendothelial matrix
2 - Aggregation — platelet-platelet cohesion
3- Secretion — the release of platelet granule proteins
4- Procoagulant activity — the enhancement
of thrombin generation
Platelet secretion :
Platelets secrete a variety of substances from their granules upon cell stimulation:
1- ADP and serotonin. 2- Fibronectin and thrombospondin.
3-Fibrinogen is released from platelet alpha granules.
4-Thromboxane A2, a prostaglandin metabolite, promotes vasoconstriction and further platelet aggregation.
5-Growth factors, such as platelet-derived growth factor (PDGF), have potent mitogenic effect on smooth muscle cells. The release of PDGF
Causes of reactive thrombocytosis:
- Hemorrage
- Surgery
- Trauma
- Iron deficiency anemia
- Splenoctomy
- Infection
- Malignant disease
- Inflamatory disease
Cause of Thrombocytopenia:Cause of Thrombocytopenia:
1- Decrease Marrow production:
Marrow failure: AA.
Marrow infiltration :leukemia , Myelidysplasia, Fibrosis….
Marrow depression: Iradiation,Chemotherapy
Selective BM depression:ethanol, drugs induced
Nutritional deficiency: megaloblastic anemia.
Hereditary causes: Fanconi”s anemia congenital megacariocytic hypoplasia.
1
Cause of Cause of Thrombocytopenia:Thrombocytopenia:
Hereditary causes: Fanconi”s anemia congenital megacariocytic hypoplasia.
2- Increased destruction of platelets:
Immune:ITP , SLE , CLL , NHL , CVD.Drud-induced: Heparin,Gold, Quinidine, Penicillins, cimetidine, digoxin.
Infection : HIV , Other Viruses , Malaria.Post Transfusion purpura.Neonatal purpura (isoimmune).
Non-immune:DIC , TTP , UHS , Congenital / acquired heart disease, Cardiopulmonary bypass , Kasabach-Merritt syndrome.
2
Endothelial cell Coagulation PropertiesEndothelial cell Coagulation Properties
Procoagulant Anti-Coagulant
CollagenFactor VIIIFibronectinIntegrinsP-endothelial cell adhesion molecule-1Selectin-ESelectin-PVon Willebrand f.Vasoconstriction
VasodilationADP aseHeparin SulfateNitric oxideProstacyclinThrombomodulinTissue factor pathway inhibitorTissue Plasminogen activator
Screening Hemostasis AssaysScreening Hemostasis Assays
CBC ,PBS Thrombocytopenia, Thrombocytosis , Giant P
PT Vit K deficiency ,Liver d. DIC , VII ,V , IX deficiency and Factor inhibitor.
PTT Heparin , DIC , Lupus anticoagulant , vWD XI, IX ,V, X, XII, HMWK , PK , factor inhibitor.
TT Heparin, DIC , Hypofibrinogenemia , Dysfibrongenemia
Bleedig T. Aspirin , Thrombocytopenia , vWD , Storage pool disease
Mixing Study Abnormal clotting time corrects w ith a deficiency dose not correct with an inhibitor.
Drugs Affecting PlateletDrugs Affecting Platelet
Strong Inhibitors
Aspirin
Abciximab (anti gpIIb/IIIa)
Ticlopidine (anti ADP)
NSAFD
Moderate Inhibitors
Antibiotics
Penicillins cepholosporins
nitrofurantoin
Dextran
Fibrinolytics
Heparin
Hetastrach
Weak Inhibitors
Alcohol
Hitroglycerin
Nitroprusside
Classification of congenital disorders of platelet Classification of congenital disorders of platelet functionfunction1- Disorders of adhesion: Von Willebrand disease bernared-Soulier syndrome2- Disorders of aggregation: Congenital afibrinogenemia Glansmann thrombasthenia3- Disorders of platelet secretion: a- Granules abnormality Storage pool deficiency Quebec platelet disordes b- Primary secretion defects reseptor defects Gaq deficiency Phospholipase C-B2 deficiency Defect in Ca++ mobilization Defect in protein phosphorylation (pleckstrin) c- Abnormalities in arachidonic acid pathways