What type of membrane depolarization is associated with the action potential?
a) secondary;
b) primary;
c) the action potential is not associated with depolarization.
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:
a) -65 mV;
b) -60 mV;
c) -53 mV.
Choose the correct statement:
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.
The neuron “threshold potential” is:
a) the Na+ equilibrium potential;
b) the membrane potential which activates voltage-gated Na+ channels;
c) the Nernst potential for potassium ions.
After an excitation of an action potential, the Na+ current across the membrane:
а) decreases about 100 times;
d) remains constant;
с) increases about 500 times.
During the depolarization phase of the action potential in neurons, the positive ion current is due to:
а) Na+ influx;
b) K + efflux;
c) Ca2+ influx.
213. During the repolarization phase of the action potential in neurons, the negative ion current is due to:
a) Na+ influx;
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?
a) positive correlation;
inverse correlation;
c) no correlation.
The action potential phenomenon is found:
a) inmost human cells;
b) in muscle and nerve cells;
c) only innerve cells.
In neurons, the action potential is initiated by:
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.
Which of the following processes signifies the end of the depolarization phase of the action potential?
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.
What type of membrane transport processes have predominant role during the action potential?
a) active membrane transport;
b) passive membrane transport;
c) active transport during depolarization and passive during repolarization.
What causes the appearance of trace potentials in neurons?
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.
Local responses in neurons are caused by:
a) spontaneously;
b) below-threshold stimulus;
c) above-threshold stimulus.
What is the correlation between the magnitude of the minimal threshold stimulus and the excitability of the membrane?
a) inverse;
b) positive;
What is the meaning of “threshold stimulus”?
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.
For which of the following scenarios the neuron has the highest excitability?
a) the membrane potential is at resting level;
b) the membrane is hyper-polarized;
c) the membrane is depolarized.
Which of the following factors has an effect on the excitability of the neuron?
a) the membrane potential at the moment of stimulation;
b) the activity of the sodium-potassium pumps;
c) the activity of the Ca2+ pumps.
The refractory period in excitable cells is:
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.
What is the sequence and the types of membrane ion currents during period of the action potential in neurons?
a) Na+ influx and K+ efflux;
b) Na+ influx, Ca2+influx, and K+ efflux;
c) K+influx and Na+efflux.
What is the explanation for the constant (non-damping) amplitude of the propagating action potential along the membrane?
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.
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?
a) K+ ions;
b) Na+ions;
c) Ca2+ions.
The propagation of the action potential along the membrane is carried out as:
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.
Is there a correlation between the propagation speed of the action potential along the axon, and the electrical resistance of the intracellular fluid?
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.
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?
a) the speed increases with the number of voltage-gated Na+ channels;
b) the speed decreases with the number of voltage-gated Na+ channels;
Which of the following membrane potentials propagates without attenuation (decrease in amplitude) along the length of the membrane?
a) trace potential;
b) action potential;
c) electrotonic potential.
The absolute refractory period is:
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.
The relative refractory period is:
What is the “resting potential”, and what cause is it?
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.
The resting membrane potential in excitable cells is close to the equilibrium potential of this ion species:
a) sodium;
b) calcium;
c) potassium.
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?
a) positive;
b) negative;
c) zero.
How is the equilibrium potential for given ion species established across the membrane?
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.
What type of response is triggered in excitable cells when stimulated with an over-threshold stimulus?
a) generation of electrotonic potential;
b) generation of Donnan potential;
c) generation of action potential.
What is the electric potential on the outside of the membrane relative to the inside, during the resting state of the cell?
a) negative;
b) zero;
c) positive.
During the resting state of the cell, the concentration of Na+ ions is higher in:
a) the extracellular space;
b) the intracellular space;
c) concentration is the same on both sides.
The ions that participate in Goldman equation are:
a) Na+, K+, Cl-
b) Na+, K+, Ca2+
c) Na+, Cl-, Ca2+
The resting potential in nerve cells is about:
a) -70 mV;
b) -70 kV;
c) -70 μV.
The equilibrium potential for Na+ is:
The repolarization phase of the axonal action potential is due to:
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.
246.Bioelectrical measure of the strength of a sub-threshold stimulus is:
a) the strength of the graded potential;
b) the frequency of action potentials;
c) the adaptation to the stimulus.
Choose the correct sequence of events during the evolution of an action potential:
a) hyperpolarization, repolarization, depolarization;
b) depolarization, repolarization, hyperpolarization;
c) depolarization, hyperpolarization, repolarization.
The term “influx” is usually associated with:
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.
Which of the following bioelectrical processes initiates the action potential?
a) depolarization of the membrane;
b) repolarization of the membrane;
c) hyperpolarization of the membrane.
During the depolarization stage in neurons there is influx of:
a) Ca2+ions;
c) K+ions.
Choose the INCORRECT statement regarding Nernst equation for potassium ions across the membrane:
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.
The term “resting potential” applies to:
a) excitable cells;
b) muscle cells only;
c) nerve cells only.
Goldman equation is used to calculate:
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.
How is the “resting potential” of the cellular membrane defined?
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.
The resting potential for most excitable cells falls in the region between:
a) E = (-10 -30) mV;
b) E = (-60 -90) mV;
c) E = (-30 +50) mV;
The resting membrane potential is due (among other factors) to the high permeability of the membrane to:
a) potassium ions;
b) sodium ions;
chloride ions.
During the depolarization phase of the axonal membrane, there is increase for its permeability for:
a) Na+ ions;
b) K+ions;
c) Clions.
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?
a) 60 mV;
c) -100 mV.
What is meaning of “R” in the Nernst equation?
a) the radius of the K+ion;
b) the universal gas constant;
c) the Faraday’s constant.
Which cells maintain non zero membrane potential?
a) nerve cells;
b) all excitable cells;
c) all living cells.
Action potential in neurons is:
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.
Equilibrium potential for given ion species is:
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.
Depolarization is:
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.
The resting potential in excitable tissues has a magnitude close to
a) potassium equilibrium potential;
b) sodium equilibrium potential;
c) calcium equilibrium potential.
The excitation of a neuron is related to:
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.
