The following processes depend on changes in membrane conductance to Na and K. a. Action potential b. depolarization c. repolarization d. all of them

The following processes depend on changes in membrane conductance to Na and K.
a. Action potential
b. depolarization
c. repolarization
d. all of them
by

1 Answer

Answer :

all of them
by

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Last Answer : nerve impulse

Which process begins after Na influx essentially stops at its plateu a. Depolarization b. Repolarization c. both d. none

Description : Which process begins after Na influx essentially stops at its plateu a. Depolarization b. Repolarization c. both d. none

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Conductance is reciprocal of a. permeability b. action potential c. resistance d. depolarization

Description : Conductance is reciprocal of a. permeability b. action potential c. resistance d. depolarization

Last Answer : resistance

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 permeability of the cell membrane to potassium ions d. during depolarization, the potential of the neurone changes from -70mV to +40mV

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Last Answer : during depolarization, the potential of the neurone changes from -70mV to +40mV

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 wave The P wave is an ECG characteristic reflecting conduction of an electrical impulse through the atria. c) PR interval The PR interval is a component of an ECG tracing reflecting conduction of an electrical impulse through the AV node. d) QT interval The QT interval is an ECG characteristic reflecting the time from ventricular depolarization to repolarization.

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Last Answer : a) QRS complex The QRS complex represents ventricular depolarization

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 reflect Purkinje fiber repolarization. It is usually seen when a patient’s serum potassium level is low. b) T wave The T wave is an ECG characteristic reflecting repolarization of the ventricles. It may become tall or “peaked” if a patient’s serum potassium level is high. c) P wave The P wave is an ECG characteristic reflecting conduction of an electrical impulse through the atria. d) QT interval The QT interval is an ECG characteristic reflecting the time from ventricular depolarization to repolarization.

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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.

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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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

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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

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Last Answer : A. Enhancement of resting membrane potential

The action potential of a neuron a. is initiated by efflux of Na+ b. is terminated by efflux of K+ c. declines in amplitude as it moves along the axon d. results in a transient reversal of the concentration gradient of Na+ across the cell membrane e. is not associated with any net movement of Na+ or K+ across the cell membrane

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Last Answer : is terminated by efflux of K+

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.

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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 intracellular microtubules and inhibition of glucose uptake in the worm D. Tegument damage and leakage of contents of the worm

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The resting membrane potential of a cell a. is dependent on the permeability of the cell membrane to K+ being greater than the permeability to Na+ b. falls to zero immediately when Na+, K+ ATPase in the membrane is inhibited c. is usually equal to the equilibrium potential for K+ d. is usually equal to the equilibrium potential for Na+ e. is markedly altered if the extracellular Na+ concentration is increased

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Chemiosmotic theory of ATP synthesis in the chloroplasts and mitochondria is based on (a) membrane potential (b) accumulation of Na+ ions (c) accumulation of K+ ions (d) proton gradient.

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In cardiac cells, adenosine (a) Causes shortening of action potential duration (b) Depolarization (c) Increase in normal automaticity (d) All of the above

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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) Relaxes vascular smooth muscle (d) Slows the depolarization phase of the action potential in AV nodal cells (e) Used in management of supraventricular tachycardias

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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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The effect of noradrenaline on the heart include: a. tachycardiac b. increased duration of the cardiac action potential c. decreased potassium conductance of the membranes of pacemaker cells d. increased strength of cardiac contraction

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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's disease c. the EOG light rise is produced by depolarization of the basal membrane of the retinal pigment epithelium d. all above

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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

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At the muscle end-plate, d-tubocurarine reduces the: A. Number of Na+ channels B. Duration for which the Na+ channels remain open C. Ion conductance of the open Na+ channel D. Frequency of Na+ channel opening

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At resting stage permeability of `K^(+)` ion is more comparatively `Na^(+)` ion through axonal membrane

Description : At resting stage permeability of `K^(+)` ion is more comparatively `Na^(+)` ion through axonal membrane

Last Answer : At resting stage permeability of `K^(+)` ion is more comparatively `Na^(+)` ion through axonal membrane

At resting stage permeability of `K^(+)` ion is more comparatively `Na^(+)` ion through axonal membrane

Description : At resting stage permeability of `K^(+)` ion is more comparatively `Na^(+)` ion through axonal membrane

Last Answer : At resting stage permeability of `K^(+)` ion is more comparatively `Na^(+)` ion through axonal membrane

Binding of acetylcholine to its receptors increases the permeability of cell membrane to (A) Ca++ (B) Na+ (C) K+ (D) Na+ and K+

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Binding of gamma-aminobutyric acid to its receptors in brain increases the permeability of cell membrane to (A) Cl– (B) Na+ (C) K+ (D) Ca++

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There are two properties of the cell necessary to maintain nonequilibrium cellular composition; the first is selectivity and the second is energy conversion. Which of the following statement(s) is/are true concerning energy converting transport? a. The site of energy conversion and transport in the plasma membrane involves the phospholipid component b. The Na+-K++-ATPase derives energy from hydrolysis of extracellular ATP c. In some systems, energy inherent in the transmembrane ion gradient can be used to drive transport of a second species d. Examples of species transported via secondary active transport include hydrogen ions, calcium, amino acids and glucose

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Which ion moves freely through the plasma membrane a. Na b. Cl c. k d. HCo3

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Which ion is actively transported to the outside of cell membrane a. K b. Cl c. Na d. HCo3

Description : Which ion is actively transported to the outside of cell membrane a. K b. Cl c. Na d. HCo3

Last Answer : Na

The plasma membrane in resting condition is almost impermeable to a. K+ b. Na+ c. Cl d. HCo3

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Last Answer : Na+

In the resting state of the neural membrane, diffusion due to concentration gradients, if allowed, would drive (a) K+ into the cell (b) K+ and Na+ out of the cell (c) Na+ into the cell (d) Na+ out of the cell.

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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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Last Answer : (d) comparatively more permeable to K+ ions and nearly impermeable to Na+ ions.

Select the correct statement from the following regarding cell membrane. (a) Na+ and K+ ions move across cell membrane by passive transport. (b) Proteins make up 60 to 70% of the cell membrane. (c) Lipids are arranged in a bilayer with polar heads towards the inner part. (d) Fluid mosaic model of cell membrane was proposed by Singer and Nicolson

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The following diuretic acts on the luminal membrane of distal tubule and collecting ducts to inhibit electrogenic Na+ reabsorption so that K+ excretion is diminished and bicarbonate excretion is enhanced: A. Xipamide B. Isosorbide C. Triamterene D. Spironolactone

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Last Answer : C. Triamterene

Aldosterone increases Na+ reabsorption and K+ excretion in the renal collecting duct cells by: A. Inducing synthesis of Na+K+ATPase B. Inducing synthesis of amiloride sensitive Na+ channels C. Translocating Na+ channels from cytosolic site to luminal membrane D. All of the above

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Last Answer : D. All of the above

Select the correct statement from the following regarding cell membrane (1) Fluid mosaic model of cell membrane was proposed by Singer and Nicolson (2) Na+ and K+ ions move across cell membrane by passive transport (3) Proteins make up 60 to 70% of the cell membrane (4) Lipids are arranged in a bilayer with polar heads towards the inner part

Description : Select the correct statement from the following regarding cell membrane (1) Fluid mosaic model of cell membrane was proposed by Singer and Nicolson (2) Na+ and K+ ions move across cell membrane by ... of the cell membrane (4) Lipids are arranged in a bilayer with polar heads towards the inner part

Last Answer : (1) Fluid mosaic model of cell membrane was proposed by Singer and Nicolson

e primary mechanism by which general anaesthetics produce their action is: A. Affecting receptor operated ion channels in cerebral neurones B. Blocking voltage sensitive Na+ channels in neuronal membrane C. Depressing metabolic activity of cerebral neurones D. Blocking production of high energy phosphates in the brain

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Last Answer : A. Affecting receptor operated ion channels in cerebral neurones

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

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Last Answer : C. Hyperpolarization of nematode muscle by GABA agonistic action

The following are true about the synaptic potential: a. the Na+ and K+ currents occurs simultaneously b. is a graded potential c. the channel is ligand-gated d. the post-synaptic potential is inhibitory when depolarizing

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What is the role of Na+ in the generation of action potential? -Biology

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Thiazide diuretics enhance K+ elimination in urine primarily by: A. Inhibiting proximal tubular K+ reabsorption B. Inhibiting Na+ K+-2Cl– cotransport in the ascending limb of loop of Henle C. Increasing the availability of Na+ in the distal tubular fluid to exchange with interstitial K+ D. Potentiating the action of aldosterone

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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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The positive inotropic action of digoxin takes several hours to develop because: A. Binding of digoxin to Na+K+ATPase is slow B. After Na+K+ATPase inhibition by digoxin, Ca2+ loading of myocardial fibres occurs progressively with each contraction C. Digoxin inhibits Na+K+ATPase through modification of gene function which takes time D. Both ‘A’ and ‘B’ are correc

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Which physical quantity is measured in ‘siemens’? (1) Electric potential (2) Electrical conductance (3) Magnetic flux (4) Refractive index

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Pick out the wrong statement. (A) Reciprocal of the resistance to heat flow is called thermal conductance (B) Unit of thermal conductance is W/°K (C) Thermal conductance of a wall of thickness 'L', thermal conductivity 'k' and heat flow area 'A' is kL/A (D) None of these

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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

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