Chapter 7

25 July 2022
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question
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
answer
B) Brain and spinal cord
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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
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D) Both sympathetic and parasympathetic nervous systems
question
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.
answer
A) They transmit information from the periphery to the CNS.
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What is the functional unit of the nervous system? A) neurons B) glial cells C) the central nervous system D) axons E) the brain
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A) Neurons
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On what portion of the neuron do action potentials propagate? A) soma B) cell body C) dendrite D) axon E) nucleus
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D) Axon
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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
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A) Neurotransmitter
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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
answer
E) Axon hillock : axon terminal
question
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
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D) leak channels
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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
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E) ligand-gated channels
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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
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C) Axon hillock
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In a neuron, where are voltage-gated calcium channels located? A) dendrites B) soma C) axon hillock D) axon E) axon terminal
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E) Axon terminal
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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
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A) multipolar
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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
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C) Afferent neurons
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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
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A) Ganglia
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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
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E) Ventricular cell
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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
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A) Oligodendrocyte
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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 membrane's ion permeability E) reduce a membrane's ion permeability
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E) Reduce a membrance's ion permeability
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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
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B) Current
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Which of the following determines the resistance to an ion's 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
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B) Ion channels within the membrane
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What is the inverse of resistance? A) voltage B) current C) conductance D) impedance E) flux
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C) Conductance
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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
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E) Concentration of sodium receptors
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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.
answer
D) At the potassium equilibrium potential, there is an electrical force driving sodium ions out of the cell
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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.
answer
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.
question
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
answer
A) -55 mV
question
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
answer
C) Potassium : out of
question
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 cell's membrane potential to become more ________. A) inward : positive B) inward : negative C) outward : positive D) outward : negative E) at equilibrium : positive
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A) Inward : positive
question
The membrane potential at which there is no net flux of an ion across the membrane is called that ion's ________. A) potential difference B) action potential C) resting membrane potential D) equilibrium potential E) graded potential
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D) Equilibrium potential
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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
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A) Na+/K+ pump
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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
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D) Na+ out to K+ in leaves the inside of the cell with a net negative charge
question
Why is the electrical potential of a membrane at rest closest to potassium's equilibrium potential than to sodium's 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
answer
C) More potassium channels are open, allowing more potassium to move out of the cell
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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 potassium's equilibrium potential D) approach sodium's equilibrium potential E) approach chloride's equilibrium potential
answer
D) Approach sodium's equilibrium potential
question
As a membrane's permeability to a particular ion increases, membrane potential will move ________ that ion's ________. 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
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E) Closer to : equilibrium potential
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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
answer
A) GHK equation
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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
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A) Gating
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The opening of an ion channel increases a cell membrane's ________, whereas ________ will decrease. A) resistance : permeability B) permeability : conductance C) permeability : electrical current D) resistance : conductance E) conductance : resistance
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E) Conductance : resistance
question
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
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D) Polarized
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A change in a cell's membrane potential, such that it becomes more positive, is referred to as a ________. A) depolarization B) hyperpolarization C) hypopolarization D) polarization E) repolarization
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A) Depolarization
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A change in a cell's membrane potential, such that it becomes more negative, is referred to as a ________. A) depolarization B) hyperpolarization C) hypopolarization D) polarization E) repolarization
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B) Hyperpolarization
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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
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E) Graded potential
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The direction of change in membrane potential, in response to a stimulus that initiates a graded potential, is dependent upon ________. A) that membrane's 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
answer
E) The ion channels that are opened or closed
question
Which of the following does NOT produce graded potentials? A) the release of a neurotransmitter onto a cell body B) the release of a neurotransmitter onto a dendrite C) arrival of a suprathreshold stimulus at the axon hillock D) light impinging on a photoreceptor E) touching a sensory receptor
answer
C) Arrival of a supra threshold stimulus at the axon hillock
question
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.
answer
C) Graded potentials and action potentials are all-or-none.
question
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
answer
B) Decrement : leakage
question
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.
answer
A) Two stimuli from two sources produce graded potentials on the same neuron at the same time such that the two potentials sum.
question
) 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
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B) Depolarization only
question
The spread of voltage by passive charge movement is called ________. A) diffusion B) integration C) propagation D) electrotonic conduction E) saltatory conduction
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D) Electronic conduction
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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
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D) Axon hillock
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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
answer
A) Rapid increase in potassium permeability
question
The opening of sodium channels causes a rapid ________ of sodium that ________ the neuron's membrane. A) efflux : hyperpolarizes B) influx : hyperpolarizes C) efflux : depolarizes D) influx : depolarizes E) influx : repolarizes
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D) Influx : depolarizes
question
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
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A) Opening of sodium channels
question
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
answer
E) Closure of sodium channels and opening of potassium channels
question
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
answer
C) Time-dependent
question
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
answer
A) The activation and inactivation gates must both be open
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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
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E) Epithelial cell membrane
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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
answer
A) Opening sodium activation gates
question
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.
answer
D) Stimulus A will cause a high frequency of action potentials.
question
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
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E) Potassium flow out of the cell
question
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
answer
C) During the absolute refractory period
question
The regenerative nature of a sodium channel's 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 channels' activation gates B) opening of the inactivation gate of the same sodium channel C) opening of other sodium channels' activation gates D) closing of other sodium channels' inactivation gate E) opening of a potassium channels
answer
C) Opening of other sodium channels' activation gates
question
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
answer
D) Subthreshold
question
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
answer
A) Outward potassium current
question
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
answer
D) Closure of inactivation gates on sodium channels
question
Why will the magnitude of an action potential never reach sodium's 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
answer
D) The inward movement of sodium is countered by the outward movement of potassium
question
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
answer
D) Once the membrane potential reaches threshold, an action potential will be generated and that action potential will always be the same magnitude
question
In order for a neuron to move from the absolute to the relative refractory period, a majority of that neuron's 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
answer
A) Inactivation gates open
question
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
answer
D) Decreased potassium permeability
question
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
answer
D) Progressively reduced
question
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
answer
C) The peak level of depolarization reached
question
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
answer
D) Amplitude of
question
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
answer
C) Diameter of the axon
question
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
answer
A) The region just behind the action potential is in the absolute refractory period
question
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
answer
B) Nodes of Ranvier
question
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
answer
D) Saltatory conduction
question
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
answer
C) Diameter = 20 microns, myelinated
question
What percentage of people with diabetes develop peripheral neuropathy? A) 5 B) 10 C) 20 D) 30 E) 50
answer
D) 30
question
What percentage of people with neuropathy have it secondary to diabetes? A) 5 B) 10 C) 20 D) 30 E) 50
answer
D) 30
question
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.
answer
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.