Quiz
Practice Exam 3
Questions in this quiz (40)
1The Na/K transporter (pump) is blocked by:
- ATTX
- Blocal anesthetics
- CTEA
- Dsaxitoxin
- Enone of the above
2nAChR channels at the endplate:
- Aopen when the nAChR are activated
- Bare non-selective in that they allow positive and negative ions to pass through
- CNa and K ions pass through them by simple diffusion
- Dalso open when serotonin or glutamate is present
- Echoices A & C
3As 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:
- Aa type of presynaptic inhibition results
- Bthe nerve terminal is depolarized to -62mV
- Cthe incoming action potential at the terminal is decreased in amplitude
- Dthe amount of transmitter released is decreased
- EAll of the above
4Which of the following statements is/are true:
- Aalkalosis can cause coma
- Baction potential starts at the axon hillock
- Cin the Renshaw circuit activity of one motor neuron result in self-inhibition.
- Dremoval of Ca2+from the vicinity of axon causes inhibition of AP conduction
- Enone of the above
5Which of the following statements is/are true:
- Athe motor endplate is electrically not excitable
- Bpinocytosis is the reverse of emeiocytosis
- Cdemarcation (injury) potential is a monophasic action potential
- Dwater is a polar molecule but can cross the cell membrane freely
- Eall of the above
6What would happen to a muscle action potential if 50% of membrane sodium channels were blocked?
- Ait would be similar to a pacemaker action potential
- Bit would be similar to a heart ventricular muscle action potential
- Cit would be the same but with no relative refractory period
- Dit would be the same but with no absolute refractory period
- Eit would be of much smaller amplitude
7Postsynaptic density (opacity) is due to the presence of ______ in or beneath the membrane:
- Amitochondria
- Bmyelin
- Ckinesin
- Dsynaptic vesicles
- Enone of the above
8Multiple sclerosis (MS):
- Aalso known as ALS
- Boccurs both in the CNS and PNS
- Cis commonly known as Lou Gehrig’s disease
- Doccurs in the PNS only
- Enone of the above
9The inhibitory postsynaptic potential (IPSP):
- Ais the result of negative ions moving through ligand-gated channels into the neuron
- Bhas a brief refractory period
- Cis propagated
- Dis the cause of stimulus artifact
- Eis a depolarization
10The refractory periods (RP):
- Athe absolute RP is due to complete closure and inactivation of Na channels
- Bare due to opening of the delayed rectifier
- Ccan be seen in nerve action potentials but not in muscle action potentials
- Dchoices A & B
- Echoices A & C
11Long-term potentiation (LTP)
- Ais a form of functional synaptic plasticity
- Bis manifested as increased synaptic strength (i.e. increased EPSP)
- Cis same a perforated synapses
- Dchoices A & B
- Echoices A, B & C
12Release of neurotransmitter (NT) takes place as:
- ANT molecules in the neuroplasm diffuse across the terminal membrane through the synaptic cleft and onto the postsynaptic membrane.
- Bvesicles containing the NT are released into the synaptic cleft where they diffuse and fuse into the postsynaptic membrane.
- CNT diffuses through the connexins of the gap junction from the presynaptic to postsynaptic membrane
- Dnone of the above
13“Saturday night paralysis” is a proof that A fibers are:
- Amore susceptible to hypoxia than B fibers
- Bmore susceptible to pressure than B fibers
- Cmore susceptible to hypoxia than C fibers
- Dmore susceptible to pressure than C fibers
14When an action potential depolarizes a terminal button, Ca2+:
- Aenters the synaptic vesicles
- Bis released into the synaptic cleft
- Centers the nerve terminal
- Denters the postsynaptic membrane to generate an EPSP
- Egenerates the coated vesicles
15In the CNS, a severed or injured axon may undergo Wallerian degeneration but virtually no regeneration takes place because:
- Aastrocytes produce certain chemicals that prevent regeneration
- Bastrocytes produce scar tissue to block regeneration
- Cthere are no glial cells to lay the track for a growing axon
- Dchoices A & B
- Echoices A, B & C
16Which of the following comparisons between neurons and muscle tissue is false?
- Aresting potential is -90to -100mV in muscle fibers
- Bmuscle fibers conduct action potentials at relatively slower speeds
- Caction potentials last longer in muscle fibers
- Dmuscle fibers conduct action potentials by saltatory conduction only
17How would the plateau action potential be affected if calcium channels were blocked?
- Ait would look like a pacemaker action potential
- Bit would look like a regular (muscle or nerve) action potential
- Cit would not change in any aspect
- Dit would change shape but would have no absolute refractory period
- Enone of the above
18The All-or-nothing rule applies to:
- AIPSP
- BmEPP
- CEPSP
- DEPP
- Enone of the above
19While 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?
- Amolecule X is transported from outside to the cytoplasm.
- Bthe transport process involves a carrier protein.
- Cthe system exhibits saturation.
- Dchoices A & B
- Echoices A,B &C
20Exocytosis is involved in:
- AA neurotransmitter release
- Baction of dynein and kinesin
- Csimple diffusion
- Dactive transport
- Enone of the above
21The amplitude of action potential in an axon is dependent on:
- Aextracellular Na+
- Bextracellular K+
- Cintracellular Ca2+
- Dextracellular Cl-
- Enone of the above
22SNAREs and synaptotagmin:
- ASNAREs are proteins that exist only on the vesicles
- BSNAREs exist on the vesicles as well as on the cytoplasmic side of the nerve terminal
- CSNAREs bind calcium ion directly
- DCalcium ions bind synaptotagmin
- Echoices B & D
23A drug closes potassium channels of an axon and causes a 15 mV change in the resting membrane potential (RMP). The change is:
- Asimilar to EPSP
- Bsimilar to action potential
- Csimilar to IPSP
- Da reversal potential
- Ea plateau potential
24Which of the following statements is/are false?
- Aa single Schwann cell forms a single segment of myelin on peripheral axons
- BEPP results from opening of acetylcholine-gated channels
- Cpresynaptic inhibition requires longer time to develop than postsynaptic inhibition.
- Dsynaptic spines are presynaptic nerve terminal
- Eall of the above
25Which of the following statement(s) is false?
- Aaction potential starts at the initial segment of the axon
- Boligodendrocytes are found within the brain.
- CNa -K pump exists on the myelinated part of a nerve
- Da single oligodendrocyte can myelinate multiple segments of axon membrane
- Ere-creation of electrical signal across synapses is called transmission
26Which of the following is True?
- Aall-or-none law applies to action potential from a single neuron
- Bthe ion channels in the synaptic area of all chemical synapses are G-protein dependent
- CConduction velocity in myelinated axons depends on whether the nerve is sensory or motor
- DPhagocytosis is an endocytosis whereas pinocytosis is an exocytosis
- EIntracellular fluid has more Na+ and less K+ than extracellular fluid
27The membranes that most commonly form synapses are the _____and the _____.
- Aaxon terminals--dendrites
- Bsoma--glial
- Cdendrites--soma
- Daxon terminals--soma
- Echoices A and D are correct.
28Which of the following is true regarding axoplasmic transport?
- AThe kinesin molecule is involved in retrograde transport.
- BRetrograde transport involves moving substances from the soma to the axon
- CThe kinesin molecule is involved in anterograde transport
- DThe dynein molecule is involved in anterograde transport.
29Which of the following is/are true of oligodendrocytes and Schwann cells?
- ASchwann cells provide myelin for peripheral nerve cells.
- BA single Schwann cell wraps a single segment of a peripheral nerve cell.
- CA single oligodendrocyte can myelinate up to 50 segments of axon membrane.
- DOligodendrocytes are found within the brain.
- EAll of the above are correct.
30The force that moves sodium ions out of the axon is
- Aretrograde transport.
- Belectrostatic pressure.
- Cthe sodium-potassium transporter.
- Ddiffusion.
- Eantidromic flow
31Choose the correct ion channel action with the resulting effect:
- Aentry of a positive ion--hyperpolarization
- B entry of a negative ion--hyperpolarization
- Cexit of a negative ion--hyperpolarization
- Dexit of a positive ion--depolarization
- Echoices B and D are correct.
32The “all-or-none law” refers to the observation that an action potential (AP):
- Awill diminish to near zero when transmitted down a long axon.
- Bis conducted more rapidly down the axon as it reaches the axon terminal.
- Cis produced whenever the membrane potential reaches threshold.
- Dwhen triggered, the amplitude of AP is the same rate regardless of the inputs to the neuron.
- Etravels only in one direction
33The essential event for the release of neurotransmitter from the presynaptic membrane is
- Athe hyperpolarization of the axon membrane.
- Bthe activation of the sodium-potassium pumps.
- Cthe influx of calcium ions into the axon terminal.
- Dthe opening of channels within the microtubules.
- Ethe arrival of an EPSF at the axon terminal.
34In which portion of a neuron would you expect to find the largest number of small vesicles?
- Athe active (release) zone
- Bjust before the axon hillock
- Cthe soma
- Dthe dendritic spines
- Ebeneath the postsynaptic membrane
35Choose the correct statement about receptors:
- Aionotropic--more time required to open an ion channel
- Bmetabotropic--direct opening of an ion channel
- Cmetabotropic--rapid short-lived effects on ion channels
- Dionotropic--direct opening of an attached ion channel
36Which of the following will “neutralize” an EPSP?
- Aopening a chloride channel
- Ballowing intracellular anions to leave the cell
- Cclosing a potassium channel
- Dfurther opening a sodium channel
- Echoices B and D are correct.
37The process, which blocks the postsynaptic potentials (EPSP and IPSP) induced by most neurotransmitters is:
- Ainhibition of the postsynaptic receptor.
- Bfacilitation of transmitter release.
- Cenzymatic degradation of the transmitter molecule.
- Dinhibition of axonal transport.
- Ereuptake of the molecule into the axon terminal.
38The absolute refractory period of a neuron
- Ais due to the high negative polarity of the inside neuron.
- Boccurs only during the repolarization phase.
- Coccurs only during the depolarization phase.
- Doccurs during depolarization and the first part of repolarization phase.
39The summation of EPSPs from numerous presynaptic nerve fibers converging at the exact same time onto one postsynaptic neuron called
- Aspatial summation.
- Blong-term potentiation.
- Ctemporal summation.
- Dsynaptic plasticity.
40Which of the following is true of the action potential?
- ADuring the action potential, the interior becomes even more negative.
- BThe potassium channels are opened at a lower voltage than are sodium channels.
- CThe sodium channels are opened at a lower voltage than are potassium channels.
- DThe action potential requires 5 msec for completion.
- EThe overshoot is due to a prolonged change in sodium conductance.
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