HematologyTest3HemostasisI

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victimsofadown
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274766
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HematologyTest3HemostasisI
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2014-05-19 05:49:23
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HematologyTest3HemostasisI
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HematologyTest3HemostasisI
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  1. What are the interacting factors in hemostasis after an injury with very brief description
    • Blood vessels: reduce blood flow
    • Platelets: adhere to form aggregates, contribute to coagulation process
    • Blood coagulation factors: form fibrin clot
    • Fibrinolysis: break down cloth when healing complete
  2. Describe the 4 types of bleeding patterns
    • Petechiae: very small blood spots (<1cm)
    • Ecchymosis: small blood spots (>1cm)
    • Purpura: red/purple discoloration that doesn't go away with pressure (a bruise)
    • Joint bleeding: appears as edema, common in hemophiliacs
  3. What is the difference between an artery and a vein?
    • Artery: carries blood away from the heart
    • Vein: carries blood toward the heart
    • Capillary: connects them
  4. Describe the anatomy of an artery (in depth)
    • Tunica Interna: endothelium, basement membrane, internal elastic membrane
    • Tunica Media: mostly smooth muscle, external elastic membrane
    • Tunica Externa: Connective tissue (contains collagen)
  5. Describe the anatomy of a vein (in depth)
    • Tunica Interna: endothelium, basement membrane
    • Tunica Media: smooth muscle
    • Tunica Externa: connective tissue (contains collagen)
  6. Describe the anatomy of a capillary (in depth)
    Endothelium, basement membrane
  7. Describe the functions of Blood Vessels (contribution to clotting)
    • Vasoconstriction
    • Diverts blood flow
    • Initiation of contact-activation of platelets to adhere with subsequent aggregation
    • Contact-activation of extrinsic and intrinsic blood coagulation pathways leading to the formation of fibrin
  8. Describe the laboratory evaluation of vascular function
    • Difficult to do
    • Old test was tourniquet test (capillary fragility/Rumpel-Leedes test)
    • take blood pressure
    • increase pressure to 100 mmHg and leave for 5 minutes
    • may form petechiae
  9. Describe the acquired vascular defects of blood vessels
    • autoimmune purpura: immunoglobins attacking vascular walls
    • Purpura associated with infections: immunoglobins attacking vascular walls
    • Scurvy due to Vitamin C deficiency: 
    • Senile purpura: Old people hands
  10. Describe the congenital vascular defects of blood vessels
    • Hereditary hemorrhagic telangiectasia: autosomal dominant
    • lack of intervening capillaries between A and V causes pressure building and vein breakage
    • Much bleeding (nose, mouth, etc)
    • Nodular lesions on mucous membranes of skin and mouth
  11. Describe the development and kinetics of platelets
    • Develop from myeloid stem cell in marrow (Stimulated by thrombopoietin produced in the liver and kidney)
    • Development takes 4-5 days in bone marrow (doesn't occur in blood)
    • Megakaryoblast: 
    • Promegakaryocyte: undergoes endomitosis (division of nucleus without splitting)
    • Megakaryocyte: 2000-4000 platelets
    • Metamegakaryocyte: naked nucleus (very little cytoplasm)
  12. What is the normal range for platelets in blood? Turnover per day? Approximate location found in the body? Life Span?
    • Normal: 130-400x10^3/uL
    • Turnover: ~35x10^3/ul per day
    • Location: 2/3 in blood, 1/3 in spleen
    • Life span: 7-10 days (death - RE system in spleen, clots)
  13. Describe the anatomy of a platelet in very basic detail
    • Hyalomere: the outside
    • consists of peripheral zone and sol-gel (cytoskeletal) zone
    • Granulomere: the inside
    • consists of the organelle zone
  14. Describe the peripheral zone of a platelet in detail
    • Glycocalyx: ABO antigens, human leukocyte antigen, glycoproteins Ib, IIb, IIIa
    • Open Canalicular system:
  15. Describe the cytoskeleton zone in detail
    • Microfilaments: 
    • Microtubules:
  16. Describe the Organelle Zone in detail
    • Mitochondria: 
    • Glycogen: energy source
    • Alpha granules (20-200): beta-thromboglobulin, platelet factor 4, platelet-derived growth factor, thrombospondin
    • Dense bodies (2-10): ADP, ATP, calcium, seratonin
    • *seratonin increases vasoconstriction at site of damage
    • Lysosomes: bacteriocidal enzymes, neutral proteases, acid hydrolases
    • Dense Tubular system:
  17. Describe the functions of platelets
    • Platelet plug formation
    • Contributions to coagulation (platelet factors)
    • Transport of substances such as serotonin (vasoconstrictor)
    • Phagocytosis (highly limited by size)
  18. List the platelet factors
    • PF 1: coagulation factor V
    • PF 2: thromboplastin-like material
    • PF 3: platelet thromboplastin
    • PF 4: antiheparin factor
    • PF 5: fibrinogen coagulant factor
    • PF 6: antifibrolytic factor
    • PF 7: platelet cothromboplastin
  19. Describe the events of clotting following a vascular injury (including timeframe for each step)
    • Vascular injury
    • Vasoconstriction
    • Adherence of platelets (1-2s): caused by collagen exposure from vessels
    • Aggregation of platelets (10-20s): after granule release
    • Plug formation (1-3m): after granule release
    • Consolidation (3-5m): after addition of fibrin (formed after collagen exposure)
    • Fibrin stabilization (5-10m): after addition of fibrin stabilizing factor (FSF)
  20. Describe the substances on the platelet surface necessary for adherence (w/ info?)
    • von Willebrand's factor: produced by endothelial cells and megakaryocytes
    • carrier for Factor VIII in plasma
    • Glycoprotein Ib (in glycocalyx)
    • Platelet surface glycoproteins: IIb and IIIa in glycocalyx
    • ADP and Ca++ in granules
    • Fibrinogen
    • Thromboxane A2
  21. Describe the laboratory evaluation of platelet number and/or function
    • Quantitative platelet count (number): 
    • Bleeding time (number and function): Ivy bleeding time is 2.5-9.5 minutes (increased in thrombocytopenia, inherited platelet dysfunction, aspirin administration)
    • Platelet aggregation test (function):
    • primary wave - platelets adhere in the presence of ADP, epinephrine, ristocetin
    • secondary wave - platelets have been stimulated to secrete the substances in their organelles
  22. Describe the quantitative platelet defects
    • Thrombocytopenia: decreased production of thrombocytes
    • ineffective thrombopoiesis
    • abnormal distribution of platelets (not 1/3, 2/3)
    • increased destruction (drug-induced, idiopathic thrombocytopenia purpura, thrombotic thromocytopenia purpura)
    • Thrombocytosis: overproduction of platelets
    • essential thrombocytosis- myeloproliferative disorder
    • platelet counts up to 1 million/uL
    • high tendency to clot
  23. Describe the qualitative platelet defects
    • Aquired defects: renal disease, liver disease, drug therapy (aspirin) causing inhibition of thromboxane A2
    • Congenital defects: von Willebrand's disease (decrease in vWF, affects platelet adhesion)
    • Bernard-Soulier syndrome- decrease in glycoprotein Ib
    • Glanzmann's thrombasthenia- decrease in glycoproteins IIb and IIIa

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