Description : The following processes depend on changes in membrane conductance to Na and K. a. Action potential b. depolarization c. repolarization d. all of them
Last Answer : all of them
Description : Which of the following ECG waveforms characterizes conduction of an electrical impulse through the left ventricle? a) QRS complex The QRS complex represents ventricular depolarization b) P ... QT interval is an ECG characteristic reflecting the time from ventricular depolarization to repolarization.
Last Answer : a) QRS complex The QRS complex represents ventricular depolarization
Description : Which of the following ECG characteristics is usually seen when a patient's serum potassium level is low? a) U wave The U wave is an ECG waveform characteristic that may ... interval The QT interval is an ECG characteristic reflecting the time from ventricular depolarization to repolarization.
Last Answer : a) U wave The U wave is an ECG waveform characteristic that may reflect Purkinje fiber repolarization. It is usually seen when a patient’s serum potassium level is low.
Description : Consider the following statements: 1. Propagation of a nerve impulse in a myelinated nerve fibre is different from that of unmyelinated fibre. 2. The impulse actually travels by leaping through the nodes of Ranvier in an unmyelinated fibre 3. ... incorrect? (a) 1, 2 (b) 1, 3, 4 (c) 2 only (d) 2, 3
Last Answer : Ans:(d)
Description : 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 ... extracellular fluid to intracellular fluid (d) Na+ ions from intracellular fluid to extracellular fluid.
Last Answer : (b) Na+ ions from extracellular fluid to intracellular fluid
Description : Which process begins after Na influx essentially stops at its plateu a. Depolarization b. Repolarization c. both d. none
Last Answer : Repolarization
Description : 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
Last Answer : C. Quinidine
Description : In cardiac cells, adenosine (a) Causes shortening of action potential duration (b) Depolarization (c) Increase in normal automaticity (d) All of the above
Last Answer : Ans: A
Description : Regarding verapamil, which one of the following statements is false? (a) Angina pectoris is an important indication for the use of verapamil (b) Contraindicated in the asthmatic patient (c) ... phase of the action potential in AV nodal cells (e) Used in management of supraventricular tachycardias
Last Answer : Ans: B
Description : In the neurone: a. the magnitude of the action potential is dependent on the strength of the stimulus b. impulses can travel in both direction c. depolarization is accompanied by increased ... potassium ions d. during depolarization, the potential of the neurone changes from -70mV to +40mV
Last Answer : during depolarization, the potential of the neurone changes from -70mV to +40mV
Description : Conductance is reciprocal of a. permeability b. action potential c. resistance d. depolarization
Last Answer : resistance
Description : The most significant feature of the antiarrhythmic action of lignocaine is: A. Suppression of phase-4 depolarization in ventricular ectopic foci B. Prolongation of action potential duration C. Prolongation of effective refractory period D. Depression of membrane responsiveness
Last Answer : A. Suppression of phase-4 depolarization in ventricular ectopic foci
Description : The electrophysiological effects of digitalis on Purkinje fibres include the following except: A. Enhancement of resting membrane potential B. Decrease in the slope of phase-0 depolarization C. Increase in the rate of phase-4 depolarization D. Abbreviation of action potential duration
Last Answer : A. Enhancement of resting membrane potential
Description : During the transmission of nerve impulse through a nerve fibre, the potential on the inner side of the plasma membrane has which type of electric charge? (a) First positive, then negative and continue ... and again back to positive (d) First negative, then positive and again back to negative.
Last Answer : (d) First negative, then positive and again back to negative.
Description : Tetrodotoxin blocks nerve impulse/junctional transmission by: A. Anticholinergic action B. Depleting acetylcholine C. Blocking Na+ channels D. Blocking Ca2+ channels
Last Answer : C. Blocking Na+ channels
Description : Depolarization of axolemma during nerve conduction takes place because of (a) equal amount of Na+ and K+ move out across axolemma (b) Na+ move inside and K+ move more outside (c) more Na+ outside (d) none of these.
Last Answer : (b) Na+ move inside and K+ move more outside
Description : Local anaesthetics block nerve conduction by: A. Blocking all cation channels in the neuronal membrane B. Hyperpolarizing the neuronal membrane C. Interfering with depolarization of the neuronal membrane D. Both ‘B’ and ‘C’ are correct
Last Answer : C. Interfering with depolarization of the neuronal membrane
Description : Action potential in nerve fibers differ in a. magnitude b. duration c. both d. none of them
Last Answer : both
Description : Anthelmintic action of piperazine is due to: A. Interference with ATP generation in the worm B. Blockade of glucose uptake by the worm C. Hyperpolarization of nematode muscle by GABA agonistic action D. Depolarization of nematode muscle by activating nicotinic receptors
Last Answer : C. Hyperpolarization of nematode muscle by GABA agonistic action
Description : The most probable mechanism of action of mebendazole is: A. Depolarization of membrane and spastic paralysis of the worm B. Hyperpolarization of membrane and flaccid paralysis of the worm C. Loss of ... inhibition of glucose uptake in the worm D. Tegument damage and leakage of contents of the worm
Last Answer : C. Loss of intracellular microtubules and inhibition of glucose uptake in the worm
Description : Explain the mechanism through which a sound produces a nerve impulse in the inner ear. -Biology
Last Answer : answer:
Description : What is the difference between impulse conduction in a myelinated nerve fibre and unmyelinated nerve fibre? -Biology
Description : Direction of nerve impulse is reversed in nerve with
Last Answer : Direction of nerve impulse is reversed in nerve with A. Axo -axonic B. Axo-dendrite C. Axo -axondendritic D. None of the above
Description : Consider the following statements: 1. Even when a nerve cell is not conducting an impulse, it is actively transporting K+ and Na+ ions in and out respectively against their concentration gradients at the expense of energy 2. As a ... is/are untrue? (a) 1 only (b) 1, 2, 4 (c) 2, 4 (d) 4 only
Description : "Sodium Pump" operates in - (1) Muscle contraction (2) Heart beat (3) Nerve impulse (4) None of the above
Last Answer : (3) Nerve impulse Explanation: Na+/K+-ATPase (also known as sodium-potassium pump) is an enzyme located in the plasma them brane of virtually every human cell and is common to all cellular ... are voltagegated, which means that they can open and close depending on the voltage across the membrane.
Description : The fastest nerve impulse in humans travel at
Last Answer : eight metres per second.
Description : What is nerve impulse?
Last Answer : These are electrical pulses which travel in the body from CNS to a body parts form the body parts to CNS to carrying different messages.
Description : During the nerve impulse transmission, following ion or ions may play significant roles D A. Sodium B. Potassium C. Chloride D. All of these
Last Answer : All of these
Description : A nerve impulse is essentially a wave of A A. Electrical charge B. Mechanical Charge C. Magnetic charge D. All of the these
Last Answer : Electrical charg
Description : A nerve impulse is essentially a wave of a. mechanical charge b. electrical charge c. Both d. None
Last Answer : electrical charge
Description : A person entering an empty room suddenly finds a snake right in front on opening the door. Which one of the following is likely to happen in his neuro- hormonal control system? ... brain. (d) Sympathetic nervous system is activated releasing epinephrine and norepinephrine from adrenal cortex.
Last Answer : (a) Sympathetic nervous system is activated releasing epinephrine and norepinephrine from adrenal medulla.
Description : Impulse of heart beat originates from (a) SA node (b) AV node (c) vagus nerve (d) cardiac nerve
Last Answer : (a) SA node
Description : 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 ... promotes ionization of lignocaine D. Nodes of Ranvier are inaccessible in the resting state
Last Answer : B. Lignocaine binds more avidly to the inactivated Na+ chan
Description : A person entering an empty room suddenly finds a snake right in front on opening the door. Which one of the following is likely to happen in his neuro-hormonal control system ? (1 ... across the cleft and transmit a nerve impulse (4) Hypothalamus activates the parasympathetic division of brain
Last Answer : (2) Sympathetic nervous system is activated releasing epinephrin and norepinephrin from adrenal medulla
Description : “Sodium Pump” operates in (1) Muscle contraction (2) Heart beat (3) Nerve impulse (4) None of the above
Last Answer : Nerve impulse
Description : Consider the following statements: 1. When a nerve fibre is stimulated, a profound change is produced in the electrical properties of surface membrane and in steady potential. 2. Upon excitation, the resting potentialis suddenly changed. 3. It is due ... 1, 2, 3 (b) 2, 3 (c) 1, 2, 3, 4 (d) 1, 2, 4
Description : The following are true about an action potential in a nerve fibre: a. it occurs when its membrane potential is hyperpolarized b. it is associated with a transient increase in membrane ... permeability to potassium d. it has an amplitude which varies directly to the strength of stimulus
Last Answer : there is a decreased in membrane permeability to potassium
Description : Dantrolene sodium reduces skeletal muscle tone by: A. Reducing acetylcholine release from motor nerve endings B. Suppressing spinal polysynaptic reflexes C. Inhibiting the generation of muscle action potential D. Reducing Ca2+ release from sarcoplasmic reticulum in the muscle fibre
Last Answer : D. Reducing Ca2+ release from sarcoplasmic reticulum in the muscle fibre
Description : The following are true about potassium: a. hypokalaemia decreases the time of cardiac repolarization b. hyperkalaemia decreases cardiac contraction c. hyperkalaemia relaxes vascular smooth muscle d. all
Last Answer : all
Description : True statements about ECG include: a. the P-R interval corresponds to the duration of atrial systole b. the T-wave ends at the time of aortic valve closure c. the ST segment represents repolarization of the ventricles d. all
Description : The rate of change of linear momentum of a body falling freely under gravity is equal to it's (1) Kinetic Energy (2) Weight (3) Potential Energy (4) Impulse
Last Answer : (2) Weight Explanation: Rate of change of impulse equals the force. In case of freely falling body the only force is the weight.
Description : 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
Last Answer : A. Na+ channel blockade
Description : Which of the following agents has a direct effect on the AV mode, delaying calciumchannel depolarization? (a) Lidocaine (b) Diltiazem (c) Bretylium (d) Quinidine (e) Lbutilide
Description : True statements about EOG (electro-oculogram) include: a. the EOG light-peak to dark-trough ratio is reduced in central retinal vein occlusion b. the light peak of EOG is abnormal in Best' ... rise is produced by depolarization of the basal membrane of the retinal pigment epithelium d. all above
Last Answer : all above
Description : The effect of calcium ions on neurotransmitter release at synapses include: a. vesicular fusion b. tonic depolarization of the presynaptic neurone c. post-tetanic potentiation d. all above
Description : In the heart: a. excitation begins in the sinoatrial node b. excitation of the ventricle begins at the apex and spread to the base c. depolarization occurs from epicardium to endocardium d. all above
Description : 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
Last Answer : have the highest densities at the nodes of Ranvier
Description : 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
Last Answer : C. Is insensitive to blockade by bicuculline