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QUESTIONS1.18 A 45-year-old man on warfarin for a mechanicalmitral valve was admitted in the Accident andEmergency Department with persistent bleedingfollowing dental extraction. He was told that hiscoagulation was deranged. Which of the followingstatements about blood coagulation is CORRECT?A Absence of Ca 2+ promotes blood coagulationB Disseminated intravascular coagulation (DIC) results indepletion of fibrin split productsC Patients with haemophilia A usually have a normalbleeding timeD von Willebrand factor suppresses platelet adhesion E von Willebrand factor suppresses blood coagulationgeneral1.19 Nerve gas (organophosphate) is a weapon ofchemical warfare that kills by causing respiratoryand cardiovascular failure. The expected effect oforganophosphate poisoning on the heart wouldbe:A Decrease the force of myocardial contractions bypotentiating the vagal tone to the ventricular muscleB Decrease the rate of rhythmicity of the sinoatrial (SA)node by inducing hyperpolarisationC Depolarise cells of the SA node by closing potassiumchannels under the control of the muscarinicacetylcholine receptorD Increase the rate of rhythmicity of the SA node byincreasing the upward drift in membrane potentialcaused by sodium leakage E Increase conductivity at the atrioventricular (AV)junction by inducing depolarisation9