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56 Cards in this Set
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Process that: 1. Retains the blood w/in the vascular system during periods of injury 2. Localizes the reactions involved to the site of injury 3. Repairs and re-establishes blood flow thru the injured vessel |
Hemostasis |
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Steps in Hemostatic Response: |
1. Injury to Endothelium (vessel) 2. Primary Hemostasis 3. Secondary Hemostasis 4. Fibrinolysis |
2. Formation of primary hemostatic plug (plts have main role) 3. Formation of fibrin clot (coag proteins, major contributor 4. Removal of Clot |
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Primary Hemostasis |
1. Vasoconstriction 2. Platelet Adhesion 3. Platelet Aggregation (primary hemostatic plug at site of injury) |
Blood Vessels & Plts are involved |
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Interaction of coagulation factors to produce fibrin (secondary hemostatic plug) Fibrin Stabilization by Factor XIII |
Secondary Hemostasis |
End Product: Fibrin Clot |
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1. Release of Tissue Plasminogen Activator
2. Conversion Plasminogen to Plasmin
3. Conversion of Fibrin to Fibrin Degradation products |
Fibrinolysis |
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Vascular System |
1. Arteries 2. Veins 3. Capillaries |
Platelets: Formation of Primary Hemostatic Plug |
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When vascular injury occurs, platelets come in contact w/ subendothelium (collagen, fibronectin) and adhere to portion of it |
Platelet Adhesion |
Occurs in the presence of vWF (von Willebrand Factor) |
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Morphologic and functional change in platelets |
Platelet Activation |
Cyclooxygenase (frm plt) metabolize arachidonic acid to form prostaglandin endoperoxides converted to TXA2 |
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Inactivates enzyme cyclooxygenase |
Aspirin |
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A potent vasoconstrictor and a platelet stimulator, causing platelet secretion and aggregation |
Thromboxane A2 (TXA2) |
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Platelet granules move to the center of the plts and fuse with open canalicular system connected to the outside of the platelet; in this way the content of granules are extruded outside |
Platelet Secretion |
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Following activation the platelet undergoes a shape change caused by contraction of |
Microtubules |
Change from Disk to Spherical Shape w/ extrusion of numerous pseudopods |
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Alpha Granules: |
1. Platelet Factor 4 2. B-thromboglobulin 3. Platelet Derived Growth Factor (PDGF) 4. Thrombospondin 5. vWF 6. Fibrinogen 7. Fibronectin 8. Factor V |
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Dense Granules: |
1. ADP 2. ATP 3. Serotonin (5-HIAA) 4. Pyrophosphate 5. Magnesium 6. Calcium 7. Iron |
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Substances that promote Coagulation: |
1. HMWK 2. Fibrinogen 3. Factor V 4. Factor VIII:vWF |
All are found in Alpha Granules Factor V - Cofactor in Fibrin clot formation Fibrinogen - Converted to FIBRIN for clot formation |
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Contact activation of intrinsic coagulation pathway |
HMWK |
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Assists platelet adhesion to subendothelium to provide coagulation surface |
Factor VIII:vWF |
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Promotes Aggregation: |
1. Calcium 2. ADP 3. PF4 4. Thrombospondin |
CAPT |
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Promotes Vasoconstriction: |
1. Serotonin 2. TXA2 |
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Promotes Vascular Repair: |
1. PDGF 2. B-thromboglobulin |
PDGF - promotes smooth muscle growth for vessel repair B-thromboglobulin - Chemotactic for fibroblasts to help in vessel repair |
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Precursor to plasmin, which induces clot lysis |
Plasminogen |
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Plasmin Inhibitor, inhibits clot lysis |
A2- Antiplasmin |
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Complement System Inhibitor |
C1 Esterase Inhibitor |
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Platelet Stimulating Agents |
1. Epinephrine 2. Collagen 3. Thrombin 4. ADP |
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Platelets adhernce to one another caused by platelet stimulating agents |
Platelet Aggregation |
Fibrinogen - necessary as cofactor for platelet aggregation |
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Most common inherited vascular disorder
Localized dilation of the walls of the small blood vessels of the skin and mucous membranes |
Hereditary Hemorrhagic Telangiectasia/ Osler-Weber-Rendu Syndrome |
Walls of the affected Vessels - Thin & lack smooth muscles |
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Disorder Associated w/ tumors composed of blood vessels that commonly swell and bleed at the surface |
Congenital Hemangiomata/Kasabach-Merritt Syndrome |
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Ehlers-Danlos Syndrome |
1 |
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Marfan's Syndrome |
1 |
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Connective tissue elastic fibers in small arteries are calcified and structurally abnormal |
Pseudoxanthoma Elasticum |
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Loss of elasticity of the skin
Bruised areas commonly found on the forearms of elderly persons |
Senile Purpura |
Dec Collagen, Elastin |
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Acquired defect in synthesis of collagen & hyaluronic acid Ascorbic Acid Deficiency |
Scurvy |
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Immunologic damage to endothelial cells Gastrointestinal hemorrhage and joint swelling occur w/ purpuric rash |
Henoch-Schonlein Purpura |
Most common in children Often follows Respiratory Infection |
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Quantitative Platelet Disorders |
1. Thrombocytopenia - Dec 2. Thrombocytosis - Inc |
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Causes of Thrombocytopenia: |
1. Dec Plt Pxn 2. Dec Survival Time 3. Inc Plt Sequestration by Spleen (Splenomegally) 4. Dilution of Plt count (Massive Transfusion) |
Degree of thrombocytopenia is directly proportional to the number of units transfused |
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Dec Plt Pxn seen in: |
1. Aplastic Anemia 2. Congenital: Fanconi's Anemia 3. Acquired: - Radiation - Chemical - Drugs - Benzene |
Chloramphenicol - Antibiotic of last resort - Causes Aplastic Anemia
Aplastic Anemia -Pancytopenia, Dec RBC, WBC, PLTS |
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Dec Survival time due to Inc Destruction |
1. DIC 2. ITP |
DIC - Mass consumption ITP - D/t auto-antibodies to plts |
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Moderate Inc in Plts, Asymptomatic Seen After: Hemorrhage, Splenectomy, Blood Loss |
Reactive Thrombocytosis |
Inc RBC Inclusion |
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Marked Inc in Plts Assoc w/ Thrombotic/Hemorrhagic Complications |
Autonomous Thrombocytosis |
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Plt Count of >1000 x 10^9/L Plt Function is Abnormal |
Essential Thromobocythemia |
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Autosomal Recessive Trait
Platelets Lack GpIb
Giant Platelets, upto 20 um in diameter |
Bernard-Soulier Syndrome |
Normal Aggregation w/: Epinephrine, ADP, Collagen Dec Aggregation w/: Ristocetin |
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Autosomal Recessive Trait Dec or Absence of GPIIB-IIIa complex |
Glanzmann's Thrombasthenia |
Normal Response w/: Ristocetin Defective Primary response in presence of: ADP, Collagen, Epinep |
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Von Willebrand's Disease |
Normal w/: Epinephrine, Collagen, & ADP Dec aggregation w/: Ristocetin |
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Qualitative Plt Disorders: |
1. Platelet Adhesion -vWD -Bernard-Soulier Syndrome 2. Platelet Aggregation -Glanzmann's Thrombasthenia 3. Platelet Secretion Release Disorders (Storage Pool Defects) Alpha Granule Def: Gray Plt Syndrome, Quebec Dense Granule Def: Hermansky-Pudlak, Chediak Higashi, WAS |
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Alpha Granule deficiency which there is deficiency of Factor V Binding Protein |
Quebec Dse |
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Acquired Plt Disorders: |
1. Uremia 2. Paraproteinemia 3. Acute Myeloblastic Leukemia 4. Myeloproliferative Disorders 5. Drugs |
Acute Myeloblastic Leukemia - Megakaryocytes in the BM may be small & abnormal |
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Metabolites that are toxic to the platelets accumulate in Plasma |
Uremia |
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Coating of platelet membrane w/ abnormal proteins |
Paraproteinemia |
1. MM 2. Waldenstrom's Macroglobulinemia |
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Primary Assay to Determine alterations in Plt Function In vitro test to determine ability of plts to aggregate w/ certain aggonists |
Platelet Aggregation |
Platelet Aggregometer
PRP = Centri= 50g for 30 Mins Platelet Agonists: 1. Epinephrine 2. Collagen 3. ADP 4. Ristocetin
PRP + Agonist = O.D. Monitored |
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Measure ability of platelets to adhere in glass surfaces |
Platelet Adhesiveness (Salzmann) |
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Requires normal number of functioning platelets, calcium, ATP, & Normal Fibrinogen Level Test for Function of Plts |
Clot Retraction Time |
Methods: 1. Castor Oil/Hirschboeck 2. Stefanini 3. MacFarlane |
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Clot Retraction Time method observed for the formation of dimpling/droplet like serum on the surface of blood drop |
Castor Oil/Hirschboeck Method |
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Initial Work up for vWD |
1. CBC 2. PT 3. PTT |
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Blood Film taken from Capillary Puncture |
Poor Man's Aggregation Test |
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Primary Hemostasis screening test for platelet & vascular function
Original Test of Platelet Function |
Bleeding Time |
*Maybe prolonged in severe fibrinogen def/afibrinogenemia
Methods: 1. Duke 2. Ivy |
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Bleeding Time Method in which a 1. Blood pressure cuff is inflated to 40 mmHg 2. Calibrated spring-loaded lancet was triggered on the volar surface of forearm a few inches distal to the antecubital crease 2. Resulting wound was blotted every 30 Secs w/ filter paper until bleeding stops |
Ivy Method |
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