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Practice Exam 3

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practice
Justin Miller
Quiz by Justin Miller, updated more than 1 year ago
Justin Miller
Created by Justin Miller over 8 years ago
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Question 1

Question
The Na/K transporter (pump) is blocked by:
Answer
  • TTX
  • local anesthetics
  • TEA
  • saxitoxin
  • none of the above

Question 2

Question
nAChR channels at the endplate:
Answer
  • open when the nAChR are activated
  • are non-selective in that they allow positive and negative ions to pass through
  • Na and K ions pass through them by simple diffusion
  • also open when serotonin or glutamate is present
  • choices A & C

Question 3

Question
As a result of repetitive activity the K concentration immediately outside the nerve terminal rises to 10 meq whereas the K concentration inside decreases to 100 meq. Thus:
Answer
  • a type of presynaptic inhibition results
  • the nerve terminal is depolarized to -62mV
  • the incoming action potential at the terminal is decreased in amplitude
  • the amount of transmitter released is decreased
  • All of the above

Question 4

Question
Which of the following statements is/are true:
Answer
  • alkalosis can cause coma
  • action potential starts at the axon hillock
  • in the Renshaw circuit activity of one motor neuron result in self-inhibition.
  • removal of Ca2+from the vicinity of axon causes inhibition of AP conduction
  • none of the above

Question 5

Question
Which of the following statements is/are true:
Answer
  • the motor endplate is electrically not excitable
  • pinocytosis is the reverse of emeiocytosis
  • demarcation (injury) potential is a monophasic action potential
  • water is a polar molecule but can cross the cell membrane freely
  • all of the above

Question 6

Question
What would happen to a muscle action potential if 50% of membrane sodium channels were blocked?
Answer
  • it would be similar to a pacemaker action potential
  • it would be similar to a heart ventricular muscle action potential
  • it would be the same but with no relative refractory period
  • it would be the same but with no absolute refractory period
  • it would be of much smaller amplitude

Question 7

Question
Postsynaptic density (opacity) is due to the presence of ______ in or beneath the membrane:
Answer
  • mitochondria
  • myelin
  • kinesin
  • synaptic vesicles
  • none of the above

Question 8

Question
Multiple sclerosis (MS):
Answer
  • also known as ALS
  • occurs both in the CNS and PNS
  • is commonly known as Lou Gehrig’s disease
  • occurs in the PNS only
  • none of the above

Question 9

Question
The inhibitory postsynaptic potential (IPSP):
Answer
  • is the result of negative ions moving through ligand-gated channels into the neuron
  • has a brief refractory period
  • is propagated
  • is the cause of stimulus artifact
  • is a depolarization

Question 10

Question
The refractory periods (RP):
Answer
  • the absolute RP is due to complete closure and inactivation of Na channels
  • are due to opening of the delayed rectifier
  • can be seen in nerve action potentials but not in muscle action potentials
  • choices A & B
  • choices A & C

Question 11

Question
Long-term potentiation (LTP)
Answer
  • is a form of functional synaptic plasticity
  • is manifested as increased synaptic strength (i.e. increased EPSP)
  • is same a perforated synapses
  • choices A & B
  • choices A, B & C

Question 12

Question
Release of neurotransmitter (NT) takes place as:
Answer
  • NT molecules in the neuroplasm diffuse across the terminal membrane through the synaptic cleft and onto the postsynaptic membrane.
  • vesicles containing the NT are released into the synaptic cleft where they diffuse and fuse into the postsynaptic membrane.
  • NT diffuses through the connexins of the gap junction from the presynaptic to postsynaptic membrane
  • none of the above

Question 13

Question
“Saturday night paralysis” is a proof that A fibers are:
Answer
  • more susceptible to hypoxia than B fibers
  • more susceptible to pressure than B fibers
  • more susceptible to hypoxia than C fibers
  • more susceptible to pressure than C fibers

Question 14

Question
When an action potential depolarizes a terminal button, Ca2+:
Answer
  • enters the synaptic vesicles
  • is released into the synaptic cleft
  • enters the nerve terminal
  • enters the postsynaptic membrane to generate an EPSP
  • generates the coated vesicles

Question 15

Question
In the CNS, a severed or injured axon may undergo Wallerian degeneration but virtually no regeneration takes place because:
Answer
  • astrocytes produce certain chemicals that prevent regeneration
  • astrocytes produce scar tissue to block regeneration
  • there are no glial cells to lay the track for a growing axon
  • choices A & B
  • choices A, B & C

Question 16

Question
Which of the following comparisons between neurons and muscle tissue is false?
Answer
  • resting potential is -90to -100mV in muscle fibers
  • muscle fibers conduct action potentials at relatively slower speeds
  • action potentials last longer in muscle fibers
  • muscle fibers conduct action potentials by saltatory conduction only

Question 17

Question
How would the plateau action potential be affected if calcium channels were blocked?
Answer
  • it would look like a pacemaker action potential
  • it would look like a regular (muscle or nerve) action potential
  • it would not change in any aspect
  • it would change shape but would have no absolute refractory period
  • none of the above

Question 18

Question
The All-or-nothing rule applies to:
Answer
  • IPSP
  • mEPP
  • EPSP
  • EPP
  • none of the above

Question 19

Question
While studying the transport of molecule X across the cell membrane, you discover that as you increase the concentration of B in the extracellular fluid, the rate of transport also initially increases. If the concentration of extracellular X is further increased, the rate becomes constant. Based on this information, which of the following statements best describe this situation?
Answer
  • molecule X is transported from outside to the cytoplasm.
  • the transport process involves a carrier protein.
  • the system exhibits saturation.
  • choices A & B
  • choices A,B &C

Question 20

Question
Exocytosis is involved in:
Answer
  • A neurotransmitter release
  • action of dynein and kinesin
  • simple diffusion
  • active transport
  • none of the above

Question 21

Question
The amplitude of action potential in an axon is dependent on:
Answer
  • extracellular Na+
  • extracellular K+
  • intracellular Ca2+
  • extracellular Cl-
  • none of the above

Question 22

Question
SNAREs and synaptotagmin:
Answer
  • SNAREs are proteins that exist only on the vesicles
  • SNAREs exist on the vesicles as well as on the cytoplasmic side of the nerve terminal
  • SNAREs bind calcium ion directly
  • Calcium ions bind synaptotagmin
  • choices B & D

Question 23

Question
A drug closes potassium channels of an axon and causes a 15 mV change in the resting membrane potential (RMP). The change is:
Answer
  • similar to EPSP
  • similar to action potential
  • similar to IPSP
  • a reversal potential
  • a plateau potential

Question 24

Question
Which of the following statements is/are false?
Answer
  • a single Schwann cell forms a single segment of myelin on peripheral axons
  • EPP results from opening of acetylcholine-gated channels
  • presynaptic inhibition requires longer time to develop than postsynaptic inhibition.
  • synaptic spines are presynaptic nerve terminal
  • all of the above

Question 25

Question
Which of the following statement(s) is false?
Answer
  • action potential starts at the initial segment of the axon
  • oligodendrocytes are found within the brain.
  • Na -K pump exists on the myelinated part of a nerve
  • a single oligodendrocyte can myelinate multiple segments of axon membrane
  • re-creation of electrical signal across synapses is called transmission

Question 26

Question
Which of the following is True?
Answer
  • all-or-none law applies to action potential from a single neuron
  • the ion channels in the synaptic area of all chemical synapses are G-protein dependent
  • Conduction velocity in myelinated axons depends on whether the nerve is sensory or motor
  • Phagocytosis is an endocytosis whereas pinocytosis is an exocytosis
  • Intracellular fluid has more Na+ and less K+ than extracellular fluid

Question 27

Question
The membranes that most commonly form synapses are the _____and the _____.
Answer
  • axon terminals--dendrites
  • soma--glial
  • dendrites--soma
  • axon terminals--soma
  • choices A and D are correct.

Question 28

Question
Which of the following is true regarding axoplasmic transport?
Answer
  • The kinesin molecule is involved in retrograde transport.
  • Retrograde transport involves moving substances from the soma to the axon
  • The kinesin molecule is involved in anterograde transport
  • The dynein molecule is involved in anterograde transport.

Question 29

Question
Which of the following is/are true of oligodendrocytes and Schwann cells?
Answer
  • Schwann cells provide myelin for peripheral nerve cells.
  • A single Schwann cell wraps a single segment of a peripheral nerve cell.
  • A single oligodendrocyte can myelinate up to 50 segments of axon membrane.
  • Oligodendrocytes are found within the brain.
  • All of the above are correct.

Question 30

Question
The force that moves sodium ions out of the axon is
Answer
  • retrograde transport.
  • electrostatic pressure.
  • the sodium-potassium transporter.
  • diffusion.
  • antidromic flow

Question 31

Question
Choose the correct ion channel action with the resulting effect:
Answer
  • entry of a positive ion--hyperpolarization
  • entry of a negative ion--hyperpolarization
  • exit of a negative ion--hyperpolarization
  • exit of a positive ion--depolarization
  • choices B and D are correct.

Question 32

Question
The “all-or-none law” refers to the observation that an action potential (AP):
Answer
  • will diminish to near zero when transmitted down a long axon.
  • is conducted more rapidly down the axon as it reaches the axon terminal.
  • is produced whenever the membrane potential reaches threshold.
  • when triggered, the amplitude of AP is the same rate regardless of the inputs to the neuron.
  • travels only in one direction

Question 33

Question
The essential event for the release of neurotransmitter from the presynaptic membrane is
Answer
  • the hyperpolarization of the axon membrane.
  • the activation of the sodium-potassium pumps.
  • the influx of calcium ions into the axon terminal.
  • the opening of channels within the microtubules.
  • the arrival of an EPSF at the axon terminal.

Question 34

Question
In which portion of a neuron would you expect to find the largest number of small vesicles?
Answer
  • the active (release) zone
  • just before the axon hillock
  • the soma
  • the dendritic spines
  • beneath the postsynaptic membrane

Question 35

Question
Choose the correct statement about receptors:
Answer
  • ionotropic--more time required to open an ion channel
  • metabotropic--direct opening of an ion channel
  • metabotropic--rapid short-lived effects on ion channels
  • ionotropic--direct opening of an attached ion channel

Question 36

Question
Which of the following will “neutralize” an EPSP?
Answer
  • opening a chloride channel
  • allowing intracellular anions to leave the cell
  • closing a potassium channel
  • further opening a sodium channel
  • choices B and D are correct.

Question 37

Question
The process, which blocks the postsynaptic potentials (EPSP and IPSP) induced by most neurotransmitters is:
Answer
  • inhibition of the postsynaptic receptor.
  • facilitation of transmitter release.
  • enzymatic degradation of the transmitter molecule.
  • inhibition of axonal transport.
  • reuptake of the molecule into the axon terminal.

Question 38

Question
The absolute refractory period of a neuron
Answer
  • is due to the high negative polarity of the inside neuron.
  • occurs only during the repolarization phase.
  • occurs only during the depolarization phase.
  • occurs during depolarization and the first part of repolarization phase.

Question 39

Question
The summation of EPSPs from numerous presynaptic nerve fibers converging at the exact same time onto one postsynaptic neuron called
Answer
  • spatial summation.
  • long-term potentiation.
  • temporal summation.
  • synaptic plasticity.

Question 40

Question
Which of the following is true of the action potential?
Answer
  • During the action potential, the interior becomes even more negative.
  • The potassium channels are opened at a lower voltage than are sodium channels.
  • The sodium channels are opened at a lower voltage than are potassium channels.
  • The action potential requires 5 msec for completion.
  • The overshoot is due to a prolonged change in sodium conductance.
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