Chapter 7

In a neuron, where is the greatest concentration of voltage-gated sodium and voltage-gated potassium channels? A) dendrites B) soma C) axon hillock D) axon E) axon terminal

C) axon hillock

What is the inverse of resistance? A) voltage B) current C) conductance D) impedance E) flux

C) conductance

Which of the following axons would have the fastest conduction velocity? A) diameter = 5 microns, myelinated B) diameter = 5 microns, unmyelinated C) diameter = 20 microns, myelinated D) diameter = 20 microns, unmyelinated E) diameter = 1 micron, myelinated

C) diameter = 20 microns, myelinated

For an unmyelinated axon, conduction velocity is primarily determined by the ________. A) type of potassium channel activated B) type of sodium channel activated C) diameter of the axon D) permeability of the axonal membrane E) number of ion channels present on the membrane

C) diameter of the axon

During which of the following states are the majority of voltage-gated sodium channels closed and incapable of opening? A) at the resting membrane potential B) during depolarization C) during the absolute refractory period D) during the relative refractory period E) during the after-hyperpolarization

C) during the absolute refractory period

Why is the electrical potential of a membrane at rest closest to potassiumʹs equilibrium potential than to sodiumʹs equilibrium potential? A) more sodium channels are open, allowing more sodium to move into the cell B) more sodium channels are open, allowing more sodium to move out of the cell C) more potassium channels are open, allowing more potassium to move out of the cell D) more potassium channels are open, allowing more potassium to move into the cell E) all potassium channels are open

C) more potassium channels are open, allowing more potassium to move out of the cell

The regenerative nature of a sodium channelʹs activation gate refers to the situation where an activation gate opens causing a depolarization that triggers which of the following? A) closure of other sodium channelsʹ activation gates B) opening of the inactivation gate of the same sodium channel C) opening of other sodium channelsʹ activation gates D) closing of other sodium channelsʹ inactivation gate E) opening of a potassium channels

C) opening of other sodium channelsʹ activation gates

At the resting membrane potential, the membrane is most permeable to ________, which moves ________ the cell due to its electrochemical gradient. A) sodium : into B) potassium : into C) potassium : out of D) sodium : out of E) chloride : into

C) potassium : out of

True/ False At the resting membrane potential, a cell is at equilibrium.

False

True/ False Effector organs act as receptors that detect information about the external environment and transmit that information to the central nervous system.

False

True/ False Excitatory graded potentials are those where the stimulus initiates a hyperpolarization of the cell.

False

True/ False In temporal summation, stimuli from different sources are applied at the same time such that they overlap and sum.

False

True/ False Leak channels are most concentrated in the soma of neurons.

False

True/ False Oligodendrocytes are located in the peripheral nervous system, providing the myelin sheath that forms the nodes of Ranvier.

False

True/ False The GHK equation is used to calculate the equilibrium potential for a specific ion.

False

True/ False The Nernst equation is used to calculate the resting membrane potential.

False

True/ False The magnitude of the action potential is dependent upon the extent to which the change in membrane potential is above threshold.

False

True/ False The membrane potential of a cell is determined exclusively by that cellʹs sodium and potassium permeability.

False

True/ False Under resting conditions, the sodium channel responsible for generating an action potential is closed and incapable of opening.

False

Given a cation with an equilibrium potential of -55 mV, if the plasma membrane of the cell is permeable only to this ion, then which of the following best describes the resting membrane potential? A) -55 mV B) +55 mV C) -70 mV D) More negative than -55 mV E) More positive than -55 mV

A) -55 mV

What equation is used to calculate the membrane potential based on ion concentration gradients and permeabilities? A) GHK equation B) NAD equation C) Nernst equation D) Ficks equation E) Lotts equation

A) GHK equation

The presence of the ________ prevents the dissipation of the concentration gradient for Na +. A) Na+/K+ pump B) action potential C) equilibrium potential D) Na+/Ca2+ exchanger E) Na+/H+ antiporter

A) Na+/K+ pump

Which of the following accurately describes afferent neurons? A) They transmit information from the periphery to the CNS. B) The cell body is located in the ventral horn of the spinal cord. C) They are the most abundant class of neurons. D) They transmit information from the CNS to the periphery. E) They are typically multipolar neurons.

A) They transmit information from the periphery to the CNS.

Which of the following is an example of spatial summation? A) Two stimuli from two sources produce graded potentials on the same neuron at the same time such that the two potentials sum. B) Two rapid stimuli from the same source produce graded potentials on the neuron that sum. C) An action potential occurs at the same time as a graded potential, and they sum. D) A neuron sends out information through collaterals to several target cells. E) Two action potentials occur at the same time and sum.

A) Two stimuli from two sources produce graded potentials on the same neuron at the same time such that the two potentials sum.

A change in a cellʹs membrane potential, such that it becomes more positive, is referred to as a ________. A) depolarization B) hyperpolarization C) hypopolarization D) polarization E) repolarization

A) depolarization

Which of the following terms is NOT used to describe a bundle of axons in the central or peripheral nervous system? A) ganglia B) pathways C) tracts D) nerves E) commissures

A) ganglia

Membrane permeability is altered in the short term (milliseconds to seconds) by changes in the ________ of ion channels. A) gating B) cleavage C) production D) formation E) degradation

A) gating

In order for a neuron to move from the absolute to the relative refractory period, a majority of that neuronʹs sodium channels must have their ________. A) inactivation gates open B) activation gates closed C) inactivation gates closed D) activation gates opened and inactivation gates closed E) inactivation gates closed and activation gates closed

A) inactivation gates open

At the resting membrane potential, the electrochemical gradient for sodium across the membrane is such that the net flux for sodium movement is directed ________, thereby causing the cellʹs membrane potential to become more ________. A) inward : positive B) inward : negative C) outward : positive D) outward : negative E) at equilibrium : positive

A) inward : positive

What is the structural classification of a neuron composed of a single axon and a number of dendritic projections from the nerve cell body? A) multipolar B) bipolar C) pseudo-unipolar D) unipolar E) polar

A) multipolar

What is the functional unit of the nervous system? A) neurons B) glial cells C) the central nervous system D) axons E) the brain

A) neurons

Information is transmitted from cell to cell across the chemical synapse via a(n) ________. A) neurotransmitter B) action potential C) graded potential D) collateral potential E) neurosecretory hormone

A) neurotransmitter

16) What type of cell enhances the velocity of electrical transmission of an action potential along an axon in the central nervous system? A) oligodendrocyte B) Schwann cell C) astrocyte D) ependymal cell E) microglia

A) oligodendrocyte

The depolarization phase of the action potential is generated by a rapid ________. A) opening of sodium channels B) closure of potassium channels C) closure of sodium channels D) opening of potassium channels E) opening of chloride channels

A) opening of sodium channels

Which of the following events is fastest? A) opening sodium activation gates B) closing sodium inactivation gates C) opening voltage-gated potassium channels D) closing voltage-gated potassium channels E) closing sodium activation gates

A) opening sodium activation gates

In order to generate an action potential, the magnitude of the inward sodium current must be large enough to overcome which of the following? A) outward potassium current B) inward potassium current C) outward sodium current D) inward chloride current E) outward calcium current

A) outward potassium current

Which of the following characteristics does NOT describe an action potential? A) rapid increase in potassium permeability B) rapid reversal of membrane potential C) it does not decay over long distances D) large depolarization E) rapid increase in sodium permeability

A) rapid increase in potassium permeability

For the sodium channel to open and allow sodium into the cell, ________. A) the activation and inactivation gates must both be open B) only the activation gate must be open C) only the inactivation gate must be open D) the inactivation gate must open shortly before the activation gate opens E) the activation and inactivation gates must both be closed

A) the activation and inactivation gates must both be open

As an action potential is propagated away from the axon hillock, why does propagation continue in one direction? A) the region just behind the action potential is in the absolute refractory period B) the region just in front of the action potential is in the absolute refractory period C) the region just behind the action potential is in the relative refractory period D) the region just in front of the action potential is in the relative refractory period E) they will travel the path of least resistance

A) the region just behind the action potential is in the absolute refractory period

Why do the distributions of sodium and potassium ions across the plasma membrane of neurons not change appreciably, even following hundreds of action potentials? A) The movement of sodium and potassium ions that occurs during an action potential is countered by the passive leak of these ions when a neuron is at rest. B) The movement of sodium and potassium ions that occurs during an action potential is countered by the active transport of these ions by the Na+/K+ pump. C) The movement of sodium and potassium ions that occurs during an action potential is countered by the passive movement of these ions during the repolarization phase. D) The movement of sodium and potassium ions that occurs during an action potential is countered by the passive movement of these ions during the after-hyperpolarization. E) The movement of sodium and potassium ions that occurs during an action potential is countered by counter-transport of potassium with sodium during rest.

B) The movement of sodium and potassium ions that occurs during an action potential is countered by the active transport of these ions by the Na+/K+ pump.

Which of the following correctly lists the components of the central nervous system? A) brain and nerves B) brain and spinal cord C) spinal cord and nerves D) brain, spinal cord, and nerves E) sympathetic and parasympathetic nervous system

B) brain and spinal cord

Which of the following is the correct term for the movement of an electrical charge across a membrane? A) resistance B) current C) potential difference D) transistor E) capacitance

B) current

The ________ in graded potential that occurs as current spreads along the membrane happens as a consequence of the ________ of current across the membrane. A) elevation : leakage B) decrement : leakage C) decrement : blockade D) elevation : blockade E) elevation : generation

B) decrement : leakage

Which of the following changes in membrane potential is considered excitatory? A) hyperpolarization only B) depolarization only C) repolarization only D) both hyperpolarization and depolarization E) both hyperpolarization and repolarization

B) depolarization only

A change in a cellʹs membrane potential, such that it becomes more negative, is referred to as a ________. A) depolarization B) hyperpolarization C) hypopolarization D) polarization E) repolarization

B) hyperpolarization

Which of the following determines the resistance to an ionʹs movement across a membrane? A) enzymes on the surface of the cell membrane B) ion channels within the membrane C) receptors on the cell membrane D) the ions present on either side of the membrane E) the resting membrane potential

B) ion channels within the membrane

In myelinated nerve fibers, where do action potentials occur? A) cell body B) nodes of Ranvier C) Schwann cell D) underlying myelin sheath E) oligodendrocyte

B) nodes of Ranvier

Which of the following statements is FALSE? A) Graded potentials can sum over time but action potentials cannot. B) Graded potentials do not have refractory periods, but action potentials do. C) Graded potentials and action potentials are all-or-none. D) Graded potentials and action potentials are caused by ions moving through channels. E) Graded potentials and action potentials can change the membrane potential of adjacent areas of the membrane through electrotonic conduction.

C) Graded potentials and action potentials are all-or-none.

Which of the following best describes the electrochemical forces acting on sodium and potassium ions at the resting membrane potential? A) Forces on both sodium and potassium ions are to move into the cell. B) Forces on both sodium and potassium ions are to move out of the cell. C) The force on sodium ions is to move into the cell, and the force on potassium ions is to move out of the cell. D) The force on sodium ions is to move out of the cell, and the force on potassium ions is to move into the cell. E) There is no force on either ion to move.

C) The force on sodium ions is to move into the cell, and the force on potassium ions is to move out of the cell.

Which of the following is a functional classification of neurons that, for the most part, are bipolar in structure and carry information from the peripheral axon to the central axon? A) interneurons B) efferent neurons C) afferent neurons D) bipolar cells E) multipolar cells

C) afferent neurons

Which of the following characteristics of an action potential does NOT result directly from the refractory period? A) the lack of summation of action potentials B) the all-or-none principle of action potentials C) the peak level of depolarization reached D) the frequency of action potentials E) the unidirectional propagation of action potentials

C) the peak level of depolarization reached

The patterns of change in ion channel permeability that occur during an action potential are due to ________ gating of voltage-sensitive potassium and sodium channels. A) mechanically-induced B) ligand-driven C) time-dependent D) temperature-induced E) light-sensitive

C) time-dependent

What percentage of people with diabetes develop peripheral neuropathy? A) 5 B) 10 C) 20 D) 30 E) 50

D) 30

What percentage of people with neuropathy have it secondary to diabetes? A) 5 B) 10 C) 20 D) 30 E) 50

D) 30

Which of the following statements about sodium is FALSE? A) There is a chemical force driving sodium ions into the cell. B) At the resting membrane potential, there is an electrical force driving sodium ions into the cell. C) At the sodium equilibrium potential, there is an electrical force driving sodium ions out of the cell. D) At the potassium equilibrium potential, there is an electrical force driving sodium ions out of the cell. E) At the sodium equilibrium potential, the electrochemical force for sodium movement across the plasma membrane is zero.

D) At the potassium equilibrium potential, there is an electrical force driving sodium ions out of the cell.

The Na+/K+ pump is called an electrogenic pump because the imbalance between ________. A) Na+ in to K+ out leaves the inside of the cell with a net negative charge B) Na+ out to K+ in leaves the inside of the cell with a net positive charge C) Na+ in to K+ out leaves the inside of the cell with a net positive charge D) Na+ out to K+ in leaves the inside of the cell with a net negative charge E) ATP utilization inside the cell relative to the outside

D) Na+ out to K+ in leaves the inside of the cell with a net negative charge E) ATP utilization inside the cell relative to the outside

Stimuli A and B are both suprathreshold stimuli that last for one second, but stimulus A is stronger. Which of the following statements is TRUE? A) Only stimulus A can produce an action potential. B) The action potential produced by stimulus A will be larger than that produced by stimulus B. C) The action potential produced by stimulus A will be of longer duration than that produced by stimulus B. D) Stimulus A will cause a higher frequency of action potentials. E) A single action potential will be produced by both stimulus A and stimulus B. The action potentials produced from each stimulus will be identical in size and duration.

D) Stimulus A will cause a higher frequency of action potentials.

The time between action potentials is directly determined by the ________ the graded potential at the axon hillock. A) distance traveled by B) duration of C) frequency of D) amplitude of E) source of

D) amplitude of

If, under resting conditions, the membrane is much more permeable to sodium than potassium, what would happen to the resting membrane potential? A) be altered very little B) become more negative C) approach potassiumʹs equilibrium potential D) approach sodiumʹs equilibrium potential E) approach chlorideʹs equilibrium potential

D) approach sodiumʹs equilibrium potential

On what portion of the neuron do action potentials propagate? A) soma B) cell body C) dendrite D) axon E) nucleus

D) axon

If the graded potential remains above threshold once it reaches the ________, an action potential will be generated. A) cell body B) dendrite C) axon D) axon hillock E) nucleus

D) axon hillock

Which of the following is located in the autonomic nervous system? A) sympathetic nervous system only B) parasympathetic nervous system only C) somatic nervous system only D) both sympathetic and parasympathetic nervous systems E) both sympathetic and somatic nervous systems

D) both sympathetic and parasympathetic nervous systems

What terminates the positive feedback loop that is involved in the generation of an action potential? A) opening of activation gates on sodium channels B) closure of activation gates on sodium channels C) opening of inactivation gates on sodium channels D) closure of inactivation gates on sodium channels E) closure of potassium channels

D) closure of inactivation gates on sodium channels

Toward the end of the relative refractory period, the continued decrease in stimulus intensity required to initiate an action potential is caused by ________. A) decreased sodium permeability B) increased potassium permeability C) closure of the sodium activation gate D) decreased potassium permeability E) the number of sodium channels whose inactivation gate has not opened

D) decreased potassium permeability

The spread of voltage by passive charge movement is called ________. A) diffusion B) integration C) propagation D) electrotonic conduction E) saltatory conduction

D) electrotonic conduction

The membrane potential at which there is no net flux of an ion across the membrane is called that ionʹs ________. A) potential difference B) action potential C) resting membrane potential D) equilibrium potential E) graded potential

D) equilibrium potential

The opening of sodium channels causes a rapid ________ of sodium that ________ the neuronʹs membrane. A) efflux : hyperpolarizes B) influx : hyperpolarizes C) efflux : depolarizes D) influx : depolarizes E) influx : repolarizes

D) influx : depolarizes

What type of ion channels in the membrane of neurons allow ions to move across the membrane at rest and thereby contribute to resting membrane potential? A) voltage-gated channels B) resting channels C) potential-gated channels D) leak channels E) ligand-gated channels

D) leak channels

The all-or-none principle, associated with the action potential, states that ________. A) the positive feedback loop for the sodium channel is terminated by the inactivation gate B) there is a positive feedback loop for sodium channels that results in a rapid membrane depolarization C) all of the action potentials will be generated from the axon hillock D) once membrane potential reaches threshold, an action potential will be generated and that action potential will always be the same magnitude E) following an action potential, the membrane will be repolarized by the opening of a potassium channel

D) once membrane potential reaches threshold, an action potential will be generated and that action potential will always be the same magnitude

The fact that a cell has an electrical potential difference across its membrane makes that cell ________. A) depolarized B) hyperpolarized C) repolarized D) polarized E) polar

D) polarized

The stimulus intensity required to initiate an action potential is ________ through the course of the relative refractory period. A) stable B) increased C) unaltered D) progressively reduced E) progressively increased

D) progressively reduced

The jumping of an action potential from node-to-node is called ________. A) nodal conduction B) propagation C) electrotonic conduction D) saltatory conduction E) nodal propagation

D) saltatory conduction

The stimulation of an inadequate number of sodium channels for the generation of a positive sodium channel feedback loop is considered a ________ stimulus. A) threshold B) degenerative C) suprathreshold D) subthreshold E) regenerative

D) subthreshold

Why will the magnitude of an action potential never reach sodiumʹs equilibrium potential? A) the inactivation gate closes the sodium channel so rapidly B) the potassium channel opens slowly C) the sodium channel only opens for a short time D) the inward movement of sodium is countered by the outward movement of potassium E) the outward movement of sodium is countered by the inward movement of potassium

D) the inward movement of sodium is countered by the outward movement of potassium

An action potential originates at the ________ and travels along the axon until it reaches the ________. A) axon terminal : axon hillock B) dendrite : axon terminal C) axon hillock : dendrite D) dendrite : axon hillock E) axon hillock : axon terminal

E) axon hillock : axon terminal

In a neuron, where are voltage-gated calcium channels located? A) dendrites B) soma C) axon hillock D) axon E) axon terminal

E) axon terminal

As a membraneʹs permeability to a particular ion increases, membrane potential will move ________ that ionʹs ________. A) away from : electrical gradient B) away from : electrochemical gradient C) away from : equilibrium potential D) closer to : electrochemical gradient E) closer to : equilibrium potential

E) closer to : equilibrium potential

The repolarization phase of the action potential in a neuron is driven by the ________. A) closure of potassium channels B) opening of calcium channels C) opening of sodium channels D) opening of sodium channels and closure of potassium channels E) closure of sodium channels and opening of potassium channels

E) closure of sodium channels and opening of potassium channels

Which of the following is NOT a factor involved in the determination of resting membrane potential? A) concentration of sodium B) concentration of potassium C) presence of sodium channels D) presence of potassium channels E) concentration of sodium receptors

E) concentration of sodium receptors

The opening of an ion channel increases a cell membraneʹs ________, whereas ________ will decrease. A) resistance : permeability B) permeability : conductance C) permeability : electrical current D) resistance : conductance E) conductance : resistance

E) conductance : resistance

Which of the structures below lacks voltage-gated ion channels responsible for the production of action potentials? A) axon hillock B) axon C) nodes of Ranvier D) muscle cell membrane E) epithelial cell membrane

E) epithelial cell membrane

A ________ is a subthreshold change in membrane potential within the cell body that decays as it travels away from its point of origin. A) polarization B) hyperpolarization C) depolarization D) action potential E) graded potential

E) graded potential

What type of ion channels in the membrane of neurons open or close in response to a neurotransmitter binding to its receptor? A) voltage-gated channels B) synaptic channels C) potential-gated channels D) leak channels E) ligand-gated channels

E) ligand-gated channels

The repolarization phase of action potentials in neurons is due primarily to ________. A) increased activity of the Na+/K+ pump B) sodium flow out of the cell C) sodium flow into the cell D) potassium flow into the cell E) potassium flow out of the cell

E) potassium flow out of the cell

Which of the following best describes the function of the myelin sheath? A) decrease ion permeability in the nodes of Ranvier B) increase leakage of ions across the membrane C) decrease axonal conduction velocity D) increase a membraneʹs ion permeability E) reduce a membraneʹs ion permeability

E) reduce a membraneʹs ion permeability

The direction of change in membrane potential, in response to a stimulus that initiates a graded potential, is dependent upon ________. A) that membraneʹs threshold potential B) the gating of potassium channels only C) the gating of sodium channels only D) the changes in ion concentration across the membrane E) the ion channels that are opened or closed

E) the ion channels that are opened or closed

Which of the following cells is NOT classified as a glial cell? A) astrocyte B) ependymal cell C) oligodendrocyte D) Schwann cell E) ventricular cell

E) ventricular cell

True/ False Excitable cells are capable of producing action potentials.

True

True/ False Afferent neurons are generally bipolar neurons.

True

True/ False An ionʹs net electrochemical force will tend to move that ion across the membrane in a direction that will cause membrane potential to move toward that ionʹs equilibrium potential.

True

True/ False Axons can branch.

True

True/ False Both activation and inactivation gates of a sodium channel are stimulated at the same time by a depolarization with the inactivation gate acting more slowly than the activation gate, thereby allowing sodium to enter the cell.

True

True/ False Diabetic neuropathy can affect nerves of the autonomic nervous system.

True

True/ False During the relative refractory period, the stimulus intensity required to initiate an action potential is elevated.

True

True/ False Once an action potential is generated, it will always depolarize the neighboring membrane above threshold, ensuring the action potential will travel along the axon without interruption.

True

True/ False Schwann cells are the only glial cells in the peripheral nervous system.

True

True/ False The Na+/K+ pump is electrogenic.

True

True/ False The number of ions whose movement across the membrane creates the resting membrane potential are so few that their movement does not affect that ionʹs concentration gradient.

True

True/ False Tingling can be a sign of diabetic neuropathy.

True