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USMLE
General Pathology 1
Question | Answer |
---|---|
Antithrombogenic substances | |
Steps in hemostasis | 1. Endothelial injury relases tissue factor (activates factor VII, extrinsic pathway); exposure of thrombogenic subendothelial collagen activates factor XII (intrinsic pathway), release of vWF; decreased synthesis of antithrombogenic substances; 2. Platel |
Bernard Soulier syndrome | Autosomal recessive. Deficiency of platelet GPIb. Defective platelet adhesion |
Glanzman thrombastenia | Deficiency of Gp IIB-IIIa; defective platelet aggregation |
Immune thrombocytopenic pupura | Antiplatelet antibodies and destruction in spleen by macrophages (bing IgG coated platelets via Fc receptor). Thrombocytopenia, prolonged bleeding time, normal PT and PTT. Petechiae, ecchymoses, menorrhagia, nosebleeds. Present in Wiskot-Aldrich |
Thrombotic thrombocytopenic purpura | Platelet thrombi with scant fibrin with no activation of coagulation system. Fever, thrombocytopenia, hemolytic anemia, neurologic symptoms, renal failure. Increased bleeding time, normal PT/PTT, schistocytes |
Hemolytic uremic syndrome | Gastroenteritis with bloody diarrhea, fever, thrombocytopenia, renal failure, hemolytic anemia. Produced by verotixin-producing E. coli 0157 |
Activation of coagulation system | Intrinsic pathway (Factor XII): exposure to subendothelial collagen; Extrinsic pathway (factor VII): tissue thromboplastin by endothelium |
Kinin cascade | Hageman factor converts prekallikrein into kallikrein. HMWK is converted to bradykinin by kallikrein |
Fibrinolytic system cascade | Kallikrein activates plasminogen into plasmin which inhibits fibrin from coagulation cascade |
Vitamin K-dependant factors | Factors II, VII, IX, X. Both intrinsic and extrinsic paths need vitamin k-dependant gamma carboxylation |
Prothrombin time (PT) | Tests extrinsic and common paths. Factors V, VII, X, prothrombin and fbrinogen. Used to monitor warfarin therapy |
MOA of warfarin | Blocks epoxide reductase (activates vitamin K). Takes 3-4 days for effect due to long half life of previously carboxylated factors which are still circulating |
Partial thromboplastin time (PTT) | Tests intrinsic and common paths. Factors XII, XI, IX, VIII, X, V, prothrombin, fibrinogen. Used to monitor heparin |
DIC | Thrombocytopenia, prolonged PT/PTT, decreased fibrinogen, elevated D-dimers |
Hemophilia | Deficiency of factor VIII or IX. X-linked recessive (affects males). Bleeding at circumcision, hemarthrosis, easy bruising and hematomas. No petechiae or ecchymoses. Normal platelets and bleeding time, normal PT, prolonged PTT (intrinsic path coagulopathy |
Increased PT and PTT | Vitamin K deficiency, liver disease |
Von Willenbrand disease | bleeding from mucuous membranes, prolonged bleeding time, normal PT/PTT, abnormal response to ristocetin |
Auto mechanics | Carbon monoxide poisoning. Decreased SaO2, cherry red color of skin, headache. Rx.: 100% O2 |
Firefighters | Carbon monoxide poisoning. Decreased SaO2, cherry red color of skin, headache. Rx.: 100% O2 |
Wood stoves and space heaters | Carbon monoxide poisoning. Decreased SaO2, cherry red color of skin, headache. Rx.: 100% O2 |
Pesticide industry | Organophosphate poisoning (acetylcholinesterase inhibitors) and arsenic. Lacrimation, salivation, miosis, weakness. Rx.: atropine |
Meat packing industry | Plyvinyl chloride (PVC). Hepatic angiosarcoma |
Coal workers | Anthracosis. Pulmonary fibrosis and respiratory distress |
Insulation workers | Asbestosis. Interstitial lung fibrosis, fibrous pleural plaques, brnchogenic CA, mesotheliomas, recurrent pleural effusions, dyspnea, pleuritic chest pain |
Demolition workers | Asbestosis. Interstitial lung fibrosis, fibrous pleural plaques, brnchogenic CA, mesotheliomas, recurrent pleural effusions, dyspnea, pleuritic chest pain |
Construction workers | Asbestosis. Interstitial lung fibrosis, fibrous pleural plaques, brnchogenic CA, mesotheliomas, recurrent pleural effusions, dyspnea, pleuritic chest pain |
Shipyard workers | Asbestosis. Interstitial lung fibrosis, fibrous pleural plaques, brnchogenic CA, mesotheliomas, recurrent pleural effusions, dyspnea, pleuritic chest pain |
Dry cleaners | Carbon tetrachloride (CCL4). Liver centrilobular necrosis |
Rubber/chemical workers | Benzene. Aplastic anemia, leukemia |
Battery factory workers | Lead poisoning. MOA: denatures ferrochelatase, (microcytic anemia with ringed sideroblasts), denatures ALA dehydrase. Clinical features: depositis in epiphysis, lethargy, cognitive impairment, cerebral edema, lead colic, basophilic stipling. Dx.: blood le |
Plumbers | Lead poisoning. MOA: denatures ferrochelatase, (microcytic anemia with ringed sideroblasts), denatures ALA dehydrase. Clinical features: depositis in epiphysis, lethargy, cognitive impairment, cerebral edema, lead colic, basophilic stipling. Dx.: blood le |
Pottery paint | Lead poisoning. MOA: denatures ferrochelatase, (microcytic anemia with ringed sideroblasts), denatures ALA dehydrase. Clinical features: depositis in epiphysis, lethargy, cognitive impairment, cerebral edema, lead colic, basophilic stipling. Dx.: blood le |
Combustion of polyurethane foam during fires | Cyanide poisoning. Blocks cytochrome oxidase. Hypoxia. Rx.: nitrites (form methhemoglobin which binds cyanide before it reaches tissues), thiosulfate bind cyanide forming thiocyanate |
Dental amalgams | Mercury poisoning. Intention tremors, dementia, delirium |
Insecticides | Mercury poisoning. Intention tremors, dementia, delirium |
Hat-making industry | Mercury poisoning. Intention tremors, dementia, delirium |
Cancers produced by cigarette smoke | Lung, oral cavity, pharynx, larynx, esophagus, pancreas, kidney |
Cardiovascular disease due to cigarette smoke | Atherosclerosis (major risk factor), CAD, AMI, Buerger disease |
Respiratory disease due to cigarette smoke | Chronic bronchitis, emphysema, asthma |