In synaptic integration, summation can take place between:
IPSPs and other IPSPs but temporal summation only
IPSPs and other IPSPs or EPSPs both temporal and spatial summation
EPSPs and other EPSPs but spatial summation only.
choices 1 and 2
choices 1, 2 and 3
During plateau action potential:
the delayed rectifier channels are fully open
the inward rectifier channels are closed
the Ca2+ channels are open
choices 2 and 3
About after-potentials of an action potential evoked following repetitive activity:
the after-depolarization is partly due to slowing down of K+ efflux
the after-hyperpolarization is partly due to excessive extrusion of Na+ by the pump.
the after-hyperpolarization is partly due to excessive efflux of K+
About transport within neuron: particles can be transported within the cytoplasm:
from the nerve terminals to the cell body and is called retrograde.
from the cell body to the nerve endings and is called orthodromic.
from the nerve terminals to the cell body and is called antidromic.
The Na+-K+ transporter:
pumps 3 Na+ out and 2 K+ in through their respective channels
creates an increase in the negativity of the RMP
is a form of secondary active transport
choices 1 and 3 are true
none of the above choices are true
Amyotrophic lateral sclerosis (ALS):
lesions are more localized whereas those of multiple sclerosis (MS) are diffused
like MS, it demyelinate nerves only in the CNS
like MS, may lead to paralysis
The resting membrane potential of a nerve becomes:
less negative when Na+ concentration in extracellular fluid [Na]o is increased
less negative when [K+]o is increased
more negative when [Na+]o is increased
more negative when [Ca2+]o is increased
none of the above
If the K+ delayed rectifier channels are blocked by TEA then the nerve AP would:
look similar to the cardiac ventricular AP
look like a pacemaker AP
be blocked
look like a skeletal muscle AP
The nerve action potential:
during its up-stroke the Na+/K+ permeability ratio is small
during its down-stroke (repolarization), the K+/Na+ permeability ratio is small
its upstroke is due to Na+ activation
The compound action potential:
cannot be recorded form a single squid giant axon
is not an all-or-none response
can be only be recorded in the PNS
choices 1 and 2.
choices 1, 2 and 3.
The resting membrane potential:
supplies “potential energy” for firing action potentials
can be calculated by using a modified Nernst equation
supplies needed energy for the Na-K pump
choices 1,2 and 3
Subthreshold depolarization of the axon membrane
remains the same size at each point along the axon membrane
produces a local response
decreases in size as it sweeps along the membrane
In a myelinated axon, at which point along the axon can ion enter and leave the membrane?
the membrane segment under the Schwann cell wrapping
the axon hillock
the node of Rnavier
Which of the following is an advantage of salutatory conduction?
faster conduction
less transmitter is required to send a message across the synapse
conservation of energy: i.e. less energy is expended by the membrane
choices 1 and 3
The essential event (s) for the release of neurotransmitter from presynaptic membrane is:
the arrival of an EPSP at the axon terminal
influx of calcium ions into the axon terminal
influx of K ions into the axon terminal
Presynaptic inhibition
can be produced by chloride efflux at certain nerve terminals
it may involve AMPA receptors
longer lasting than postsynaptic inhibition
Which of the following will produce an EPSP?
opening sodium channels
closing sodium channels
opening potassium channels
opening chloride channels
closing calcium channels
Which of the following is true
oligodendrocytes exist in the brain
Schwann cells provide myelin for peripheral nerve axons
a single Schwann cell wraps a single segment of a peripheral nerve
a single oligodendrocytes can mylinate up to 50 segments of axon membrane
all of the above are correct
_________ generate scar tissue which impedes regeneration of damaged axons
astrocytes
Schwann cells
axon terminals
oligodendrocytes
dendrites
Which of the following represents the normal order of activation in neuronal transmission?
axon∏ dendrites∏soma∏axon terminals
axon terminals ∏soma∏ axon∏ dendrites
dendrites∏soma∏ axon∏ axon terminals
soma∏ axon∏ dendrites∏axon terminals
dendrites∏ axon terminals∏ soma∏ axon
The ___________ is defined as the difference in electrical charge between the intracellular side and the extracellular side of an inactive nerve cell membrane.
local potential
EPSP
action potential
membrane potential
EPP
An electric stimulus applied to an axon that moves the membrane potential from –70 to –45 mV will result in:
Match the correct synaptic event with each ion channel action:
entry of a negative ion-hyperpolarization
entry of a positive ion-hyperpolarization
exit of a positive ion-depolarization
exit of a negative ion-hyperpolarization
choices 1 and 3 are correct
Which of the following events contribute to the restoration of the membrane potential from the peak of action potential
closure of sodium channels
potassium ions move out of the cell
the sodium-potassium transporter
Regarding types of synaptic transmission: _______ is an example of ________
glutamate NMDA receptor-fast synaptic transmission
mACh receptor-fast synaptic transmission
serotonin 5-HT3 receptor-slow synaptic transmission
GABAa receptor-slow synaptic transmission
all of the above correct correct
Compared with types A and B fibers; type C fibers are:
unmyelinated
with the slowest speed of conducttion
sensitive to the action of local anesthetics
Sodium channels, K channels and Na-K pumps exist on all parts of:
myelinated nerve membrane
unmyelinated nerve membrane
muscle cell membrane
The process that blocks all postsynaptic potentials is:
blockade of the postsynaptic receptors.
inhibition of transmitter release.
degradation of the transmitter molecule by a native enzyme.
The “all-or-none law”:
does not apply to ventricular action potential
refers to the observation that an action potential is evoked whenever the membrane potential reaches threshold
does not apply to IPSP
Sodium ions:
Are involved directly in the production of action potential
cross the membrane through their specific channels during action potential by simple diffusion
responsible for formation of EPP
Which of the following will "neutralize" an EPSP?
further opening a sodium channel
allowing intracellular anions to leave the cell
closing a potassium channel
opening a chloride channel
choices 2 and 4.
Which of the following statements is correct?
CO2 and O2 are not lipid soluble substances.
Some drugs (e.g. endomethacin) stabilize lysosomal membrane, which may explain their anti- inflammatory action
specific Na+ channels are the same as acetylcholine channels.
Fast axonal transport is directly involved in conduction of impulses.
All of the above are incorrect.
Which of the following will produce an IPSP?
opening sodium channels only
opening chloride channels only
opening potassium channels only
The membranes that most commonly form synapses are the ______ and _______
motor nerve terminals ; skeletal muscle
axon terminals; dendrites
axon terminals; glial
About the reversal potential of a nerve:
different excitable tissues have different reversal potentials
it is the highest positive value the AP reaches
is also called the threshold
What type of refractory periods occurs during:
EPP- relative
EPSP-absolute
mEPP-realtive
mEPSP-absolute
none of the above is correct
The process which terminates the action of ACh at the neuromuscular junction is:
disruption of the postsynaptic receptor.
enzymatic degradation by ACh-esterases.
inhibition of ACh synthesis.
A drug that opens potassium channels of an axon and causes a 5 mV change in resting membrane potential (RMP):
that change is called depolarization
causes a 5 mV increase in the amplitude of evoked action potential
that change is called hyperpolarization
Conduction velocity of a nerve can be calculated if the following information is provided:
duration of action potentials (AP) and length of nerve
the latent period and length of nerve between electrodes
strength of the stimulus and length of nerve
the refractory periods and length of nerve
none of the above, more information is needed.
Which of the following statement(s) about compound action potential is/are False?
Compound action potential is seen when a single axon is stimulated
The first peak in a compound action potential belongs to A fiber type
A compound action potential is an all-or-none phenomenon
