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Biophysics Quiz on Chapter 6, created by Y Y on 23/06/2019.

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Chapter 6

Question 1 of 59

1

What type of membrane depolarization is associated with the action potential?

Select one of the following:

  • a) secondary;

  • b) primary;

  • c) the action potential is not associated with depolarization.

Explanation

Question 2 of 59

1

Given that the resting potential of a neuron is -70 mV, choose the threshold potential which makes it harder for the neuron to excite an action potential:

Select one of the following:

  • a) -65 mV;

  • b) -60 mV;

  • c) -53 mV.

Explanation

Question 3 of 59

1

Choose the correct statement:

Select one of the following:

  • a) the action potential propagates along the membrane with constant speed;

  • b) the action potential propagates across the membrane with constant speed;

  • c) the action potential propagates in the form of longitudinal electric current.

Explanation

Question 4 of 59

1

The neuron “threshold potential” is:

Select one of the following:

  • a) the Na+ equilibrium potential;

  • b) the membrane potential which activates voltage-gated Na+ channels;

  • c) the Nernst potential for potassium ions.

Explanation

Question 5 of 59

1

After an excitation of an action potential, the Na+ current across the membrane:

Select one of the following:

  • а) decreases about 100 times;

  • d) remains constant;

  • с) increases about 500 times.

Explanation

Question 6 of 59

1

During the depolarization phase of the action potential in neurons, the positive ion current is due
to:

Select one of the following:

  • а) Na+ influx;

  • b) K + efflux;

  • c) Ca2+ influx.

Explanation

Question 7 of 59

1

213. During the repolarization phase of the action potential in neurons, the negative ion current is due
to:

Select one of the following:

  • a) Na+ influx;

  • b) K + efflux;

  • c) Ca2+ influx.

Explanation

Question 8 of 59

1

What is the correlation between the level of membrane depolarization and the number of activated voltage-gated Na+- ion channels during the early phase of the action potential?

Select one of the following:

  • a) positive correlation;

  • inverse correlation;

  • c) no correlation.

Explanation

Question 9 of 59

1

The action potential phenomenon is found:

Select one of the following:

  • a) inmost human cells;

  • b) in muscle and nerve cells;

  • c) only innerve cells.

Explanation

Question 10 of 59

1

In neurons, the action potential is initiated by:

Select one of the following:

  • a) change of the membrane conductivity for Clions;

  • b) change of the membrane conductivity for K+ ions;

  • c) change of the membrane conductivity for Na+
    ions.

Explanation

Question 11 of 59

1

Which of the following processes signifies the end of the depolarization phase of the action potential?

Select one of the following:

  • a) inactivation of voltage-gated Na+ channels;

  • b) activation of outgoing Clion current, which compensates for the incoming Na+ current;

  • c) activation of the membrane Ca2+ pumps.

Explanation

Question 12 of 59

1

What type of membrane transport processes have predominant role during the action potential?

Select one of the following:

  • a) active membrane transport;

  • b) passive membrane transport;

  • c) active transport during depolarization and passive during repolarization.

Explanation

Question 13 of 59

1

What causes the appearance of trace potentials in neurons?

Select one of the following:

  • a) the temperature increase due to ionic currents in the intracellular space;

  • b) the membrane structural recovery processes after the action potential;

  • c) the off-equilibrium concentrations of Na+ and K+ions after the action potential.

Explanation

Question 14 of 59

1

Local responses in neurons are caused by:

Select one of the following:

  • a) spontaneously;

  • b) below-threshold stimulus;

  • c) above-threshold stimulus.

Explanation

Question 15 of 59

1

What is the correlation between the magnitude of the minimal threshold stimulus and the excitability of the membrane?

Select one of the following:

  • a) inverse;

  • b) positive;

  • c) no correlation.

Explanation

Question 16 of 59

1

What is the meaning of “threshold stimulus”?

Select one of the following:

  • a) the maximal stimulus that reaches the membrane threshold potential;

  • b) the minimal stimulus that reaches the membrane over-threshold depolarization;

  • c) a stimulus that changes the membrane potential below threshold.

Explanation

Question 17 of 59

1

For which of the following scenarios the neuron has the highest excitability?

Select one of the following:

  • a) the membrane potential is at resting level;

  • b) the membrane is hyper-polarized;

  • c) the membrane is depolarized.

Explanation

Question 18 of 59

1

Which of the following factors has an effect on the excitability of the neuron?

Select one of the following:

  • a) the membrane potential at the moment of stimulation;

  • b) the activity of the sodium-potassium pumps;

  • c) the activity of the Ca2+ pumps.

Explanation

Question 19 of 59

1

The refractory period in excitable cells is:

Select one of the following:

  • a) the duration of trace potentials following the action potential;

  • b) the period between stimulation and excitation of an action potential;

  • c) the period where new action potential is impossible or more difficult to generate.

Explanation

Question 20 of 59

1

What is the sequence and the types of membrane ion currents during period of the action
potential in neurons?

Select one of the following:

  • a) Na+ influx and K+ efflux;

  • b) Na+ influx, Ca2+influx, and K+ efflux;

  • c) K+influx and Na+efflux.

Explanation

Question 21 of 59

1

What is the explanation for the constant (non-damping) amplitude of the propagating action potential along the membrane?

Select one of the following:

  • a) the indirect influence of Clon the Na+ influx and K+ efflux;

  • b) the steady electrochemical gradients for Na+ and K+ along the length of the membrane;

  • c) the isotonic conditions between intra- and extracellular environments.

Explanation

Question 22 of 59

1

What is the ion composition of local longitudinal currents, that flow near the cellular membrane,
and allow for the propagation of action potentials along the length of myelinated axons?

Select one of the following:

  • a) K+ ions;

  • b) Na+ions;

  • c) Ca2+ions.

Explanation

Question 23 of 59

1

The propagation of the action potential along the membrane is carried out as:

Select one of the following:

  • a) consecutive depolarization of the membrane, triggered by local longitudinal currents, caused by the depolarization of the adjacent point of the membrane;

  • b) consecutive depolarization of the membrane, triggered by local longitudinal currents, emanating from the initial point of stimulation;

  • c) as an electric current flowing longitudinally along the membrane.

Explanation

Question 24 of 59

1

Is there a correlation between the propagation speed of the action potential along the axon, and the electrical resistance of the intracellular fluid?

Select one of the following:

  • a) no;

  • b) yes, increase of the resistance leads to decrease of the speed;

  • c) yes, increase of the resistance leads to increase of the speed.

Explanation

Question 25 of 59

1

Is there a correlation between the propagation speed of the action potential along the axon, and
the number of voltage-gated Na+

channels on the membrane?

Select one of the following:

  • a) the speed increases with the number of voltage-gated Na+
    channels;

  • b) the speed decreases with the number of voltage-gated Na+
    channels;

  • c) no correlation.

Explanation

Question 26 of 59

1

Which of the following membrane potentials propagates without attenuation (decrease in amplitude) along the length of the membrane?

Select one of the following:

  • a) trace potential;

  • b) action potential;

  • c) electrotonic potential.

Explanation

Question 27 of 59

1

The absolute refractory period is:

Select one of the following:

  • a) the period where a depolarised portion of the membrane cannot be re-excited and generate a new action potential;

  • b) the period where a hyper-polarised portion of the membrane can be re-excited with stronger-than-usual stimulus;

  • c) the period where a sub-threshold stimulus causes membrane depolarization insufficient to trigger an action potential.

Explanation

Question 28 of 59

1

The relative refractory period is:

Select one of the following:

  • a) the period where a depolarised portion of the membrane cannot be re-excited and generate a new action potential;

  • b) the period where a hyper-polarised portion of the membrane can be re-excited with stronger-than-usual stimulus;

  • c) the period where a sub-threshold stimulus causes membrane depolarization insufficient to trigger an action potential.

Explanation

Question 29 of 59

1

What is the “resting potential”, and what cause is it?

Select one of the following:

  • a) a self-sustained fluctuation in the membrane potential of excitable cells, caused by the sequential activation of different ion channels;

  • b) a characteristic value of the membrane potential of excitable cells in the absence of external stimuli,

    caused by the selective ion permeability of the membrane and the electrogenic work of the sodium- potassium pump;

  • c) the membrane potential of excitable cells, after depolarization, when the voltage across the membrane is zero due the equilibrium of concentration and electrical gradients.

Explanation

Question 30 of 59

1

The resting membrane potential in excitable cells is close to the equilibrium potential of this ion
species:

Select one of the following:

  • a) sodium;

  • b) calcium;

  • c) potassium.

Explanation

Question 31 of 59

1

What is the value of the membrane potential on the inside of the cell relative to the outside, during
the resting state of the cell?

Select one of the following:

  • a) positive;

  • b) negative;

  • c) zero.

Explanation

Question 32 of 59

1

How is the equilibrium potential for given ion species established across the membrane?

Select one of the following:

  • a) when forces due the concentration gradient are balanced with forces due to the electrical gradient acting on the ion species;

  • b) when the concentrations of the ions species is on both sides of the membrane are equal;

  • c) when the total amount of electric charge due to ion distribution becomes equal on both sides of the membrane.

Explanation

Question 33 of 59

1

What type of response is triggered in excitable cells when stimulated with an over-threshold
stimulus?

Select one of the following:

  • a) generation of electrotonic potential;

  • b) generation of Donnan potential;

  • c) generation of action potential.

Explanation

Question 34 of 59

1

What is the electric potential on the outside of the membrane relative to the inside, during the
resting state of the cell?

Select one of the following:

  • a) negative;

  • b) zero;

  • c) positive.

Explanation

Question 35 of 59

1

During the resting state of the cell, the concentration of Na+ ions is higher in:

Select one of the following:

  • a) the extracellular space;

  • b) the intracellular space;

  • c) concentration is the same on both sides.

Explanation

Question 36 of 59

1

The ions that participate in Goldman equation are:

Select one of the following:

  • a) Na+, K+, Cl-

  • b) Na+, K+, Ca2+

  • c) Na+, Cl-, Ca2+

Explanation

Question 37 of 59

1

The resting potential in nerve cells is about:

Select one of the following:

  • a) -70 mV;

  • b) -70 kV;

  • c) -70 μV.

Explanation

Question 38 of 59

1

The equilibrium potential for Na+
is:

Select one of the following:

  • a) positive;

  • b) negative;

  • c) zero.

Explanation

Question 39 of 59

1

The repolarization phase of the axonal action potential is due to:

Select one of the following:

  • a) diffusion of sodium in to the cell;

  • b) active transport of potassium out of the cell;

  • c) diffusion of potassium out of the cell.

Explanation

Question 40 of 59

1

246.Bioelectrical measure of the strength of a sub-threshold stimulus is:

Select one of the following:

  • a) the strength of the graded potential;

  • b) the frequency of action potentials;

  • c) the adaptation to the stimulus.

Explanation

Question 41 of 59

1

Choose the correct sequence of events during the evolution of an action potential:

Select one of the following:

  • a) hyperpolarization, repolarization, depolarization;

  • b) depolarization, repolarization, hyperpolarization;

  • c) depolarization, hyperpolarization, repolarization.

Explanation

Question 42 of 59

1

The term “influx” is usually associated with:

Select one of the following:

  • a) passive transport through ion channels from extracellular into intracellular space;

  • b) active transport through ion channels from extracellular into intracellular space;

  • c) passive transport through ion channels from intra cellular into extracellular space.

Explanation

Question 43 of 59

1

Which of the following bioelectrical processes initiates the action potential?

Select one of the following:

  • a) depolarization of the membrane;

  • b) repolarization of the membrane;

  • c) hyperpolarization of the membrane.

Explanation

Question 44 of 59

1

During the depolarization stage in neurons there is influx of:

Select one of the following:

  • a) Ca2+ions;

  • b) Na+ions;

  • c) K+ions.

Explanation

Question 45 of 59

1

Choose the INCORRECT statement regarding Nernst equation
for potassium ions across the membrane:

Select one of the following:

  • a) its good approximation for the resting potential;

  • b) considers the membrane permeable only for one ion species (K+);

  • c) it models the membrane potential during the action potential.

Explanation

Question 46 of 59

1

The term “resting potential” applies to:

Select one of the following:

  • a) excitable cells;

  • b) muscle cells only;

  • c) nerve cells only.

Explanation

Question 47 of 59

1

Goldman equation is used to calculate:

Select one of the following:

  • a) the membrane potential at rest and during the action potential;

  • b) the contribution of the Na+/K+pump for the resting membrane potential;

  • c) the duration of the action potential in neurons.

Explanation

Question 48 of 59

1

How is the “resting potential” of the cellular membrane defined?

Select one of the following:

  • a) the intracellular electric potential in close proximity to the membrane during rest;

  • b) the extracellular electric potential in close proximity to the membrane during rest;

  • c) the electric potential difference between the intracellular and extracellular regions in close proximity of the membrane during rest.

Explanation

Question 49 of 59

1

The resting potential for most excitable cells falls in the region between:

Select one of the following:

  • a) E = (-10  -30) mV;

  • b) E = (-60  -90) mV;

  • c) E = (-30  +50) mV;

Explanation

Question 50 of 59

1

The resting membrane potential is due (among other factors) to the high permeability of the
membrane to:

Select one of the following:

  • a) potassium ions;

  • b) sodium ions;

  • chloride ions.

Explanation

Question 51 of 59

1

During the depolarization phase of the axonal membrane, there is increase for its permeability
for:

Select one of the following:

  • a) Na+ ions;

  • b) K+ions;

  • c) Clions.

Explanation

Question 52 of 59

1

If the electric potential of the extracellular space is 20 mV and the potential of the intracellular
space is -80 mV (relative to a common reference point), what would be the membrane potential of
the cell?

Select one of the following:

  • a) 60 mV;

  • b) -60 mV;

  • c) -100 mV.

Explanation

Question 53 of 59

1

What is meaning of “R” in the Nernst equation?

Select one of the following:

  • a) the radius of the K+ion;

  • b) the universal gas constant;

  • c) the Faraday’s constant.

Explanation

Question 54 of 59

1

Which cells maintain non zero membrane potential?

Select one of the following:

  • a) nerve cells;

  • b) all excitable cells;

  • c) all living cells.

Explanation

Question 55 of 59

1

Action potential in neurons is:

Select one of the following:

  • a) the rapid depolarisation followed by repolarization that propagates along the cellular membrane;

  • b) the specific magnitude of the membrane potential when concentration and electrical gradients are equal and opposite in direction;

  • c) the change in the amphiphilic properties of the membrane lipids allowing for electric charge redistribution between intra cellular and extracellular fluids.

Explanation

Question 56 of 59

1

Equilibrium potential for given ion species is:

Select one of the following:

  • a) the membrane potential during the resting state of the cell, when the membrane is not permeable to the ion species;

  • b) the membrane potential when the ion species are free to move across, and concentration and electrical gradients are balanced;

  • c) the state when the membrane is equally permeable to K+ and Na+ ion species.

Explanation

Question 57 of 59

1

Depolarization is:

Select one of the following:

  • a) the decrease of the absolute value of the membrane potential;

  • b) the increase of the absolute value of the membrane potential;

  • c) decrease of the value of the membrane potential relative to the resting potential.

Explanation

Question 58 of 59

1

The resting potential in excitable tissues has a magnitude close to

Select one of the following:

  • a) potassium equilibrium potential;

  • b) sodium equilibrium potential;

  • c) calcium equilibrium potential.

Explanation

Question 59 of 59

1

The excitation of a neuron is related to:

Select one of the following:

  • a) changes in the electrical conductivity of the cellular membrane;

  • b) exchange of signal molecules between receptors of the cellular and nuclear membranes;

  • c) activation of the process of cellular division.

Explanation

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