A resting nerve is relatively resistant to blockade by lignocaine compared to one which is repeatedly stimulated because: A. Lignocaine penetrates resting nerve membrane poorly B. Lignocaine binds more avidly to the inactivated Na+ channel C. Nerve impulse promotes ionization of lignocaine D. Nodes of Ranvier are inaccessible in the resting state

A resting nerve is relatively resistant to blockade by
lignocaine compared to one which is repeatedly
stimulated because:
A. Lignocaine penetrates resting nerve membrane poorly
B. Lignocaine binds more avidly to the inactivated Na+ channel
C. Nerve impulse promotes ionization of lignocaine
D. Nodes of Ranvier are inaccessible in the
resting state
by

1 Answer

Answer :

B. Lignocaine binds more avidly to the inactivated Na+ chan
by

Related questions

yocardial Na+ channel blockade by lignocaine has the following characteristic: A. It blocks inactivated Na+ channels more than activated channels B. It blocks activated Na+ channels more than inactivated channels C. It delays rate of recovery of Na+ channels D. It produces more prominent blockade of atrial than ventricular Na+ channels

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Last Answer : A. It blocks inactivated Na+ channels more than activated channels

The following is not true of local anaesthetics: A. The local anaesthetic is required in the unionized form for penetrating the neuronal membrane B. The local anaesthetic approaches its receptor only from the intraneuronal face of the Na+ channel C. The local anaesthetic binds to its receptor mainly when the Na+ channel is in the resting state D. The local anaesthetic combines with its receptor in the ionized cationic form

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Last Answer : C. The local anaesthetic binds to its receptor mainly when the Na+ channel is in the resting state

The principal action common to all class I antiarrhythmic drugs is: A. Na+ channel blockade B. K+ channel opening C. Depression of impulse conduction D. Prolongation of effective refractory period

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Last Answer : A. Na+ channel blockade

Sensitivity of a nerve fibre to blockade by lignocaine depends on: A. Whether the fibre is sensory or motor B. Whether the fibre is myelinated or nonmyelinated C. Internodal distances in the fibre D. Both ‘B’ and ‘C’ are correct

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Ceftriaxone has all the following attributes except: A. It has a long plasma half life of 8 hours B. It can cause bleeding by prolonging prothrombin time C. It has attained high cure rates in multiresistant typhoid infection D. It penetrates CSF poorly and therefore not effective in meningitis

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Last Answer : D. It penetrates CSF poorly and therefore not effective in meningitis

When a neuron is in resting state i.e., not conducting any impulse, the axonal membrane is (a) comparatively more permeable to Na+ ions and nearly impermeable to K+ ions (b) equally permeable to both Na+ and K+ ions (c) impermeable to both Na+ and K+ ions (d) comparatively more permeable to K+ ions and nearly impermeable to Na+ ions.

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The following is not true of quinidine: A. It blocks myocardial Na+ channels primarily in the open state B. It has no effect on myocardial K+ channels C. It produces frequency dependent blockade of myocardial Na+ channels D. It delays recovery of myocardial Na+ channels

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Initial bradycardia caused by intramuscular injection of atropine is believed to be caused by: A. Stimulation of medullary vagal centre B. Stimulation of vagal ganglia C. Blockade of M2 receptors on SA nodal cells D. Blockade of muscarinic autoreceptors on vagal nerve endings

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Initial bradycardia caused by intramuscular injection of atropine is believed to be caused by: A. Stimulation of medullary vagal centre B. Stimulation of vagal ganglia C. Blockade of M2 receptors on SA nodal cells D. Blockade of muscarinic autoreceptors on vagal nerve endings

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he following is true of nifedipine except: A. It can aggravate urine voiding difficulty in elderly males with prostatic hypertrophy B. It promotes Na+ retention by a renal tubular action to cause ankle oedema as side effect C. It can inhibit insulin release from pancreas D. At high doses it can paradoxically increase the frequency of angina pectori

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riiodothyronine differs from thyroxine in that: A. It is more avidly bound to plasma proteins B. It has a shorter plasma half life C. It is less potent D. It has a longer latency of action

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17.2 Triiodothyronine differs from thyroxine in that: A. It is more avidly bound to plasma proteins B. It has a shorter plasma half life C. It is less potent D. It has a longer latency of action (

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In most axons, the myelin sheath is interrupted at intervals of about 1 millimeter or more. These interruptions are called the: a) glial b) nodes of Ranvier (pron: ron-vee-ay) c) collaterals d) nodes of Babinet

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The following are true about the sodium channels: a. they are made up of polypeptide chains b. have the highest densities at the nodes of Ranvier c. open in response to depolarization d. remain open as long as depolarization is maintained

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Frequency dependent cardiac calcium channel blockade is exhibited by: A. Verapamil B. Nifedipine C. Felodipine D. Amlodipin

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The GABAB receptor: A. Is an intrinsic ion channel containing receptor B. Mediates neuronal depolarization C. Is insensitive to blockade by bicuculline D. Regulates intracellular cAMP

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During the propagation of a nerve impulse, the action potential results from the movement of (a) K+ ions from intracellular fluid to extracellular fluid (b) Na+ ions from extracellular fluid to intracellular fluid (c) K+ ions from extracellular fluid to intracellular fluid (d) Na+ ions from intracellular fluid to extracellular fluid.

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Tetrodotoxin blocks nerve impulse/junctional transmission by: A. Anticholinergic action B. Depleting acetylcholine C. Blocking Na+ channels D. Blocking Ca2+ channels

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Which of the following statement is correct for node of Ranvier of nerve? (a) Neurilemma is discontinuous. (b) Myelin sheath is discontinuous. (c) Both neurilemma and myelin sheath are discontinuous. (d) Covered by myelin sheath.

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Lignocaine is the preferred antiarrhythmic for emergency control of cardiac arrhythmias following acute myocardial infarction because: A. It has a rapidly developing and titratable antiarrhythmic action B. It causes little myocardial depression and hypotension C. It has broad spectrum antiarrhythmic efficacy in atrial as well as ventricular arrhythmias D. Both ‘A’ and ‘B’ are correct

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Low concentration of bupivacaine is preferred for spinal / epidural obstetric analgesia because: A. It has a longer duration of action B. It can produce sensory blockade without paralysing abdominal muscles C. It distributes more in maternal tissues so that less reaches the foetus D. All of the above are correct

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Neomycin is widely used as a topical antibiotic because: A. It is active against a wide range of bacteria causing superfecial infections B. It rarely causes contact sensitization C. It is poorly absorbed from the topical sites of application D. All of the above are correct

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The following antibiotic penetrates blood-CSF barrier the best: A. Erythromycin B. Gentamicin C. Tetracycline D. Chloramphenicol

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What is true of cefpirome: A. It is a fourth generation cephalosporin B. It easily penetrates porin channels of gram negative bacteria C. It inhibits type I β-lactamase producing enterobacteriaceae D. All of the above

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The following is not true of morphine: A. Its 2-glucuronide metabolite is an active analgesic B. Its active metabolite penetrates blood-brain barrier better than morphine C. Its oral: parenteral activity ratio is 1:4 D. It undergoes enterohepatic cycling

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Started within 4-6 hours of acute myocardial infarction, which of the following drug(s) can reduce the area of necrosis and the attendant mortality: A. Propranolol B. Glyceryl trinitrate C. Lignocaine D. Both ‘A’ and ‘B’ are correct

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Which of the following drugs depresses automaticity of SA node as well as ectopic foci, abbreviates action potential duration of Purkinje fibres, and slows atrioventricular conduction: A. Propranolol B. Lignocaine C. Procainamide D. Bretylium

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Select the drug which is used by intravenous infusion for emergency control of tachycardia and sudden rise in blood pressure: A. Amiodarone B. Lignocaine C. Esmolol D. Disopyramide

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The following is an orally active lignocaine congener used for both acute as well as chronic ventricular arrhythmias: A. Mexiletine B. Flecainide C. Moricizine D. Propafenone

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The following is true of procainamide except: A. It generates an active metabolite in the body B. Its plasma half-life is longer than that of quinidine C. On long-term use, it can cause systemic lupus erythematosus like illness D. It is effective in many cases of ventricular extrasystoles, not responding to lignocaine

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The following antiarrhythmic drug has the most prominent anticholinergic action: A. Disopyramide B. Quinidine C. Procainamide D. Lignocaine

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The antiarrhythmic drug which decreases both rate of depolarization (phase 0) as well as rate of repolarization (phase 3) of myocardial fibres is: A. Lignocaine B. Propranolol C. Quinidine D. Verapamil

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Select the most suitable antiarrhythmic drug for counteracting ventricular extrasystoles due to digoxin toxicity: A. Lignocaine B. Quinidine C. Verapamil D. Amiodarone

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Which of the following statements is true for lignocaine: A. It is an ester-linked local anaesthetic B. It is not likely to exhibit cross-sensitivity with procaine C. It has a shorter duration of action than procaine D. It is not a surface anaesthetic

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The local anaesthetic having high cardiotoxic and arrhythmogenic potential is: A. Lignocaine B. Procaine C. Bupivacaine D. Ropivacaine

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Last Answer : C. Bupivacaine

Which of the following is a poor surface anaesthetic: A. Procaine B. Lignocaine C. Tetracaine D. Benoxinate

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Last Answer : A. Procaine

The following local anaesthetic raises BP instead of tending to cause a fall: A. Cocaine B. Dibucaine C. Lignocaine D. Procaine

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Metronidazole is selectively active against anaerobic organisms because: A. Aerobes have an active transport mechanism to pump it out of their cell B. Only anaerobes reduce it to generate the reactive nitro radical C. It is rapidly inactivated in the presence of oxygen D. It binds to DNA of anaerobes with high affinity

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N-acetyl cysteine is beneficial in acute paracetamol poisoning because: A. It reacts with paracetamol to form a nontoxic complex B. It inhibits generation of the toxic metabolite of paracetamol C. It is a free radical scavenger D. It replenishes hepatic glutathione which in turn binds the toxic metabolite of paracetamol

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The following is true of propafenone except: A. It is a weak Na+ channel blocker B. It markedly delays recovery of myocardial Na+ channels C. It has additional β-adrenergic blocking property D. It slows anterograde as well as retrograde conduction in the WPW bypass tract

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