ES 342 Practice Test & Practice Questions Review
What functional type of neuron is most prevalent in the vertebrate nervous system? a. afferent and efferent neurons b. interneurons c. glial cells d. Renshaw cells
b. interneurons
Calculate nerve conduction velocity assuming an axon diameter of 10 microns (unmyelinated):
5 m/s
In an experiment, an investigator (1) isolates a mammalian motor nerve and places it in oxygenated Ringer's solution (Solution A which contains normal ionic concentrations), (2) inserts an intracellular electrode through the cell membrane, measures the resting membrane potential (RMP), (3) stimulates the nerve, and (4) measures the action potential (AP), and also (5) collects the amount of transmitter released. The investigator then replaces the Ringer's solution with a second oxygenated solution (solution B) containing a Na++ conc. of 170 mM and a K+ conc. of 7.5 mM. (Amount of Ca++ is unchanged) What happens to the height of the AP in the second solution?
Increased
In an experiment, an investigator (1) isolates a mammalian motor nerve and places it in oxygenated Ringer's solution (Solution A which contains normal ionic concentrations), (2) inserts an intracellular electrode through the cell membrane, measures the resting membrane potential (RMP), (3) stimulates the nerve, and (4) measures the action potential (AP), and also (5) collects the amount of transmitter released. The investigator then replaces the Ringer's solution with a second oxygenated solution (solution B) containing a Na++ conc. of 170 mM and a K+ conc. of 7.5 mM. (Amount of Ca++ is unchanged) Would the amount of transmitter release in response to a single AP be different in solution B? If yes, how?
No, amount of transmitter release would be unchanged.
In an experiment, an investigator (1) isolates a mammalian motor nerve and places it in oxygenated Ringer's solution (Solution A which contains normal ionic concentrations), (2) inserts an intracellular electrode through the cell membrane, measures the resting membrane potential (RMP), (3) stimulates the nerve, and (4) measures the action potential (AP), and also (5) collects the amount of transmitter released. The investigator then replaces the Ringer's solution with a second oxygenated solution (solution B) containing a Na++ conc. of 170 mM and a K+ conc. of 7.5 mM. (Amount of Ca++ is unchanged) Would you expect conduction velocity to be altered in the second solution?
No, conduction velocity would be unchanged.
In an experiment, an investigator (1) isolates a mammalian motor nerve and places it in oxygenated Ringer's solution (Solution A which contains normal ionic concentrations), (2) inserts an intracellular electrode through the cell membrane, measures the resting membrane potential (RMP), (3) stimulates the nerve, and (4) measures the action potential (AP), and also (5) collects the amount of transmitter released. The investigator then replaces the Ringer's solution with a second oxygenated solution (solution B) containing a Na++ conc. of 170 mM and a K+ conc. of 7.5 mM. (Amount of Ca++ is unchanged) How does the RMP in the second solution compare with that of in the first?
RMP is depolarized and becomes more positive (towards zero)
Which of the following characteristics pertain to local potentials (circle all that apply)? a) Display spatial decrement (decrease) b) Propagated without decrement c) Show temporal summation d) Amplitude is related to stimulus strength
a) Display spatial decrement (decrease) c) Show temporal summation d) Amplitude is related to stimulus strength
The axoplasm (internal fluid) of the motor neuron is replaced with a synthetic axoplasm with a potassium concentration of 160 mM/L H20. Other factors (ionic conc.) remaining equal, the resting membrane potential would be: a) Hyperpolarized b) Unchanged c) Depolarized
a) Hyperpolarized
Indicate factors which could account for an increase in the amplitude of an excitatory post-synaptic potential (EPSP). a) Temporal and spatial summation of several concomitant EPSP's. b) Depolarization of the post-synaptic element c) Both of the above d) Temporal and spatial summations of several concomitant inhibitory post-synaptic potentials (IPSP). e) All of the above
a) Temporal and spatial summation of several concomitant EPSP's.
Pre-synaptic inhibition can be mediated at : a) axo-axonal synapses b) axo-somatic synapses c) axo-dendritic synapses d) a and b e) all of the above
a) axo-axonal synapses
Which of the following receptors are G-protein coupled (metabotropic) receptors (circle all that apply): a) muscarinic ACh receptors b) nicotinic ACh receptors c) Gaba-a receptors d) Gaba-b receptors e) Dopaminergic receptors
a) muscarinic ACh receptors d) Gaba-b receptors e) Dopaminergic receptors
In most neurons, the cell body represents what percent of the cell's total volume? a. 10% b. 30% c. 50% e. 70%
a. 10%
Fast retrograde transport is best described as: a. Active transport (i.e., requiring energy) of material from the cell periphery to the soma b. Passive transport of material from the periphery to the cell body c. The primary mechanism by which soluble proteins used to make up the fibrillar elements of the cytoskeleton are transported d. a and c e. b and c
a. Active transport (i.e., requiring energy) of material from the cell periphery to the soma
The cell bodies of somatic afferent nerve fibers are located in: a. the dorsal horn area of the spinal cord b. dorsal root ganglia c. muscle fibers d. the ventral horn area of the spinal cord
b. dorsal root ganglia
The synaptic delay (the arrival of an action potential in terminal region to depolarization of the post synaptic membrane) between two neurons is determined to be virtually undetectable. The synapse represents: a. An electrical synapse b. A directly gated synapse c. An indirectly gated synapse d. Could be either b or c
a. An electrical synapse
In an experiment, an investigator (1) isolates an axon and places it in oxygenated Ringer's solution (Solution containing normal ionic concentrations), (2) inserts an intracellular electrode through the cell membrane, measures the resting membrane potential, (3) stimulates the axon, and (4) measures the action potential (See record A). The investigator then replaces the Ringer's solution with a second oxygenated solution of a different ionic content, and again records the axon's resting membrane potential and action potential (see record B). On the basis of these data, how do you think the second solution differs from the original Ringer's solution (higher peak in solution A than B) The second solution contains: a. a lower concentration of sodium ions b. a lower concentration of potassium ions c. a higher concentration of sodium ions d. a and b e. b and c
a. a lower concentration of sodium ions
Choline-acetyltransferase is: a. responsible for the synthesis of acetylcholine (ACh) b. responsible for the breakdown of ACh c. responsible for the re-uptake of ACh by the pre-synaptic membrane d. blocked by curare e. a and c
a. responsible for the synthesis of acetylcholine (ACh)
Select the correct order of events occurring in the generation of an action potential: 1. threshold is reached 2. depolarization of the nerve membrane 3. activation of electrically gated sodium channels 4. onset of electrically gated sodium channel inactivation 5. peak potassium conductance through electrically gated channels a) 1, 2, 3, 4, 5 b) 2, 1, 3, 4, 5 c) 2, 1, 3, 5, 4 d) 3, 2, 1, 4, 5 e) Order is not predictable
b) 2, 1, 3, 4, 5
Within the neuron, axonal transport mechanisms have been identified and classified as fast anterograde (FA), slow anterograde (SA), and fast retrograde (FR). The material transported by these different mechanism travel at different rates. From fastest (list first) to slowest (list last), what is the order of rate (speed) of transport? a) FA > SA > FR b) FA > FR > SA c) FR > FA > SA d) FR = FA > SA e) FR > FA = SA
b) FA > FR > SA
Which of the following characteristics pertain to action potentials ? a) Display spatial decrement (decrease) b) Propagated without decrement c) Show temporal summation d) Amplitude is related to stimulus strength e) b and d
b) Propagated without decrement
The rising phase of the action potential is due to: a) The outward flow of potassium ions b) The inward flow of sodium ions c) Both of the above d) The inward flow of calcium ions e) All of the above
b) The inward flow of sodium ions
The conduction velocity along a 2 um diameter axon is 11.0 m/sec. This neuron is likely to be classified as: a) a large diameter myelinated fiber b) a small diameter myelinated fiber c) a large diameter unmyelinated fiber d) a small diameter unmyelinated fiber e) none of the above, since not enough information was provided
b) a small diameter myelinated fiber
The average concentration of Na+ in the extracellular space is: a. 15.0 mmol/L H2O b. 150.0 mmol/L H2O c. 5.0 mmol/L H2O d. 100.0 mmol/L H2O
b. 150.0 mmol/L H2O
Nerve stimulation test reveal a general reduction in conduction velocity along several different peripheral nerves consistent with segmental demyelination. The condition(s) could be: a. Multiple Sclerosis b. Guillain-Barre Syndrome c. Lambert-Eaton Mysthenic Syndrome d. a and b e. b and c
b. Guillain-Barre Syndrome
The resting membrane potential of neurons is determined primarily by: a. Gated K+ channels b. Non-gated K+ channels c. Both of the above d. Gated Na+ channels e. Non-gated Na+ channels
b. Non-gated K+ channels
On the basis of these data, how do you think the second solution differs from the original Ringer's solution (second solution closer to EK+): 1. The second solution contains: a. a lower concentration of sodium ions b. a lower concentration of potassium ions c. a higher concentration of sodium ions d. a and b e. b and c
b. a lower concentration of potassium ions
For glial cells, the resting membrane potential is best described as: a. a active process requiring an expenditure of energy b. a passive process requiring no expenditure of energy c. determined primarily by the permeability of K+, and to a lesser extent by the permeability of Na+ d. a and c e. b and c
b. a passive process requiring no expenditure of energy
The following action potential is recorded from a somatic efferent neuron: In the action potential illustrated in the previous question (H-I is depolarization, I-J is repolarization, G-H is graded potential) a. interval H-I is caused by an active transport of sodium ions into the cell b. interval H-I is caused by diffusion of sodium ions into the cell c. interval I-J is caused by active transport of potassium ions d. interval G-H is caused by active transport of sodium ions e. a and c
b. interval H-I is caused by diffusion of sodium ions into the cell
Which of the following statement most accurately summarizes the resting membrane potential (RMP)? a. it exists only when no ions are moving across the nerve membrane b. it has as its primary cause potassium efflux c. it has as its primary cause sodium efflux d. a and b e. b and c
b. it has as its primary cause potassium efflux
In the above example (membrane permeable at rest to a single ionic species), the resting membrane potential: a. will eventually depolarize to levels above threshold if the oxygen supply to the neuron is impaired b. will remain steady if the oxygen delivery is impaired c. will eventually hyperpolarize if oxygen delivery is impaired
b. will remain steady if the oxygen delivery is impaired
A axon in the PNS is completely severed 10 cm from its terminal region. Wallerian degeneration takes place in the distal segment. Under optimal conditions, re-innervation of its' target will occur: a. within 2 weeks b. within 2 month of the lesion c. within 4 months of the lesion d. within 6 months of the lesion e. not likely to occur
b. within 2 month of the lesion
Which of the following statement most accurately summarizes the nervous systems ability to change following disease or injury? a) Both the CNS and PNS possess the ability to adapt, and always use identical compensatory mechanisms. b) The ability to adapt following injury/disease is never noted in the CNS. c) Both the CNS and PNS possess the ability to adapt, although compensatory mechanisms for a given deficit can be remarkably different d) Only the CNS has the ability to adapt following injury/disease. e)No evidence of plasticity has been demonstrated in either the mature CNS or PNS
c) Both the CNS and PNS possess the ability to adapt, although compensatory mechanisms for a given deficit can be remarkably different
A myelinated axon of unknown size is found to conduct the action potential at a velocity of 55 m/sec. What is the diameter of it's axon? a. 1 micron b. 5 microns c. 10 microns d. 15 microns
c. 10 microns
The synaptic delay (the arrival of an action potential in terminal region to depolarization of the post synaptic membrane) between two neurons is determined to be 5 msec. What type of synapse is this likely to represent? a. An electrical synapse b. A directly gated synapse c. An indirectly gated synapse d. Could be either b or c
c. An indirectly gated synapse
Guillain-Barre syndrome and multiple sclerosis are two common disorders that associated with demyelination in the peripheral nervous system (PNS) and central nervous system (CNS), respectively. Functional recovery can occur in both disorders by what mechanism? a. Remyelination by Schwann cells in PNS and by oligodendrocytes in CNS b. Migration of electric gated sodium channels in PNS and remyelination in CNS c. Remyelination in PNS and migration of electric gated sodium channels in CNS d. Migration of electric gated sodium channels in PNS and CNS
c. Remyelination in PNS and migration of electric gated sodium channels in CNS
The conduction velocity along a 20 um diameter axon is 11.0 m/sec. This fiber is likely to be classified as: a. a large diameter myelinated fiber b. a small diameter myelinated fiber c. a large diameter unmyelinated fiber d. a small diameter unmyelinated fiber e. none of the above, since not enough information was provided
c. a large diameter unmyelinated fiber
In the previous question (see diagram above), the conduction velocity of the action potential was determined to be 15 m/sec. The diameter of the (unmyelinated) axon is: a. less than 10 microns b. 10 microns c. greater than 10 microns
c. greater than 10 microns
The motor molecule responsible for fast anterograde axonal transport is: a. myosin b. actin c. kinesin d. tropomyosin e. dynein
c. kinesin
If the permeability of a resting (non-active) nerve cell to potassium ions is increased while the permeability of the cell to sodium ions remains constant (unchanged from that normally at rest). The resting membrane potential will: a. be unaffected b. move toward zero (depolarize: become more positive) c. move away from zero (hyperpolarize: become more negative)
c. move away from zero (hyperpolarize: become more negative)
In an experiment, an investigator (1) isolates an axon and places it in oxygenated Ringer's solution (Solution containing normal ionic concentrations), (2) inserts an intracellular electrode through the cell membrane, measures the resting membrane potential (RMP), (3) stimulates the axon, and (4) measures the action potential (AP), and also (5) collects the amount of transmitter released. The investigator then replaces the Ringer's solution with a second oxygenated solution of a different ionic content, and again records the nerves RMP, AP, amount of neurochemical transmitter released. The investigator notes that the RMP and AP in both solutions are identical. However, in the second solution, no release of transmitter occurs. On the basis of these findings, how do you think the second solution differs from the original Ringer's solution The second solution contains: a. no sodium ions b. no potassium ions c. no calcium ions d. no chloride ions e. b and c
c. no calcium ions
In an experiment (read Bear, Box 4.1), an investigator (1) isolates an axon and places it in oxygenated Ringer's solution (Solution containing normal ionic concentrations), (2) inserts an intracellular electrode through the cell membrane, measures the resting membrane potential, (4) stimulates the axon, and (5) measures the action potential (See record A). The investigator then replaces the Ringer's solution with a second oxygenated solution of a different ionic content, and again records the axon's resting membrane potential and action potential (see record B). In the experiment outlined above, what would ultimately (after about 30 min) occur if the oxygen supplying the Ringer's solution is turned off? a. the membrane would be slightly depolarized b. the amplitude of the action potential would be reduced c. the membrane would depolarize to levels above threshold d. a and b e. none of the above
c. the membrane would depolarize to levels above threshold
What would be the consequence of increasing the permeability of a neuron to K+ above resting levels on the RMP? (Assume the cells permeability to other ions remain unchanged from that at rest). a) The cell (neuron) will hyperpolarize (move away from zero) to levels below the Ek+ b) The cell will depolarize (move towards zero) c) The cell will hyperpolarize and will reach the Ek+ d) The cell will hyperpolarize but to levels above the Ek+
d) The cell will hyperpolarize but to levels above the Ek+
GABA-a receptors are: a) directly gated receptors b) always G-protein coupled receptors c) always associated with inhibitory post-synaptic potentials of the post-synaptic membrane d) a and c e) b and c
d) a and c
Conduction velocity along an axon is determined by: a. the diameter of the axon b. the degree or extent of myelination c. the length of the axon d. a and b e. all the above are important determinants of conduction velocity
d. a and b
If a neuron a rest is permeable to only a single ionic species (for example, only K+), the resting membrane potential is: a. determined quantitatively by the Nernst equation b. equal to the equilibrium potential for that ion c. close, but not equal to the equilibrium potential for that ion d. a and b e. b and c
d. a and b
Muscarinic ACh receptors are: a. located on skeletal muscle at the neuromuscular junction b. G-protein coupled receptors c. associated with IPSP's or EPSP's d. b and c e. a and c
d. b and c
The resting membrane potential of glial cells is: a. slightly more positive (depolarized) than the equilibrium potential for sodium b. slightly more negative (hyperpolarized) than the equilibrium constant for potassium c. slightly more positive than the equilibrium potential for potassium d. equal to the equilibrium potential for potassium
d. equal to the equilibrium potential for potassium
In the action potential illustrated in the previous question (H-I is depolarization, I-J is repolarization, G-H is graded potential) The after hyperpolarization is represented by what interval? a. interval G-H b. interval H-I c. interval I-J d. interval J-K e. after hyperpolarization is not demonstrated in the above example.
d. interval J-K
The following action potential is recorded from a neuron: In the action potential illustrated above (depolarization portion of AP) a. interval j-k is caused by passive efflux of sodium ions b. interval j-k is caused by passive influx of potassium ions c. interval j-k is caused by passive efflux of potassium ions d. interval j-k is caused by increased permeability to both Na+ and K+ ions e. c and d
d. interval j-k is caused by increased permeability to both Na+ and K+ ions
Somatic efferent (motor neurons) fibers are classified as: a. unipolar cells b. bipolar cells c. pseudo-unipolar cells d. multipolar cells
d. multipolar cells
The cell bodies of somatic efferent nerve fibers are located in: a. the dorsal horn area of the spinal cord b. dorsal root ganglia c. muscle fibers d. the ventral horn area of the spinal cord
d. the ventral horn area of the spinal cord
Which of the following influences the amplitude and time course of recorded inhibitory post-synaptic potentials (IPSP's)? a) Amount of inhibitory (hyperpolarizing) neuro-transmitter released by presynaptic endings b) Number of presynaptic inhibitory endings that are active in a local region c) Both of the above d) Discharge frequency in inhibitory presynaptic endings (i.e. rate of transmitter release) e) All of the above are correct
e) All of the above are correct
The resting membrane potential of a neuron is dependent on all of the following with the exception of: a) The sodium-potassium pump b) The presence of large non-diffusible anions within the neuron c) The concentration difference for potassium across the neuron d) The inherent difference in permeability of the membrane to sodium and potassium e) None of the above since all are important factors
e) None of the above since all are important factors
All of the following receptors are G-protein coupled receptors with the exception of: a) muscarinic ACh receptors b) nicotinic ACh receptors c) Gaba-a receptors d) a and c e) b and c
e) b and c
As a result of a gun shot wound, corticospinal tract fibers (CNS Axons) of a young police officer are severed 12 cm from their spinal projection. Wallerian degeneration takes place in the distal segment of the severed neurons. Under optimal conditions, re-innervation and thus re-use of the affected limb will occur within: a) 10 days b) 20 days c) 40 days d) 80 days e) not likely to occur
e) not likely to occur
Damage of a nerve cell (neuron) can be associated with alterations or dysfunctions of: a. the injured neuron b. intact neurons that receive synapses from the injured neuron c. intact neurons that synapse onto the injured neuron d. a and b e. Alterations can occur in all of the above
e. Alterations can occur in all of the above
Microtubules are the essential stationary tract used for what type of axonal transport? a. fast anterograde axonal transport b. slow axonal transport c. fast retrograde transport d. all of the above e. a and c
e. a and c
Slow anterograde transport is best described as: a. Active transport (i.e., requiring energy) of material from the cell body towards the periphery b. Passive transport of material from the cell body to the periphery c. The primary mechanism by which soluble proteins used to make up the fibrillar elements of the cytoskeleton are transported d. a and c e. b and c
e. b and c
Astrocytes serve the following functions with the exception of: a. buffering function by taking up certain neurotransmitters from the synaptic area b. nutritive function c. buffering function by taking up excess potassium released during high activity d. act as scavengers and remove neuronal debris e. none of the above since all are functions of astrocytes
e. none of the above since all are functions of astrocytes
