Test
Practice Exam 2
Preguntas del test (40)
1The Na/K transporter (pump) is blocked by:
- ATTX
- Blocal anesthetics
- CTEA
- Dnone of the above
- Eall of the above
2nAChR channels at the endplate:
- Aopen when the endplate is depolarized
- Bare non-selective in that they allow positive and negative ions to pass through
- Cions pass through them by simple diffusion
- Dopen when serotonin or glutamate is present
- Enone of the above
3Axons X and Y are myelinated and of equal diameter, suppose that, in X the internodal distance is 10 nm while in Y the internodal distance is 20 nm. Based on this information:
- Aaxon X is faster conducting than Y
- Baxon Y is faster conducting than X
- Caxons X and Y have equal conduction velocity
- Daxon X save more energy than axon Y
- Eaxons X and Y save same amount of energy
4As 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: (hint: log 10=1)
- Aa type of presynaptic inhibition results
- Bthe nerve terminal is depolarized
- Cthe incoming action potential is decreased in amplitude
- Dthe amount of transmitter released is less
- EAll of the above
5The fate of Na and K ions that enter and leave respectively during the action potential:
- ANa ions exit through their channels just before they close
- BK ions enter through the delayed rectifier channels before they close
- Cthe Na/K pump returns the ions to their original concentrations
- DNa ions are trapped, but they slowly diffuse out across the membrane.
- Eall of the above
6Which of the following statements is/are incorrect:
- Aalkalosis can cause excitation of the CNS
- Btermination of epileptic seizures can be due to Wedensky inhibition
- Cin the Renshaw circuit activity of one motor neuron result in self-inhibition as well as inhibition of an antagonist second motor neuron
- Dremoval of Ca from the vicinity of a synapse causes increased excitability of the axon but also causes inhibition of synaptic transmission
- Enone of the above
7Which of the following statements is/are incorrect:
- Athe motor endplate is electrically not excitable
- Bpinocytosis is the reverse of phagocytosis
- Cdemarcation (injury) potential is a monophasic action potential
- Dwater is a polar molecule but can cross the cell membrane freely
- Eall of the above
8If the voltage-regulated sodium channels failed to become inactivated, then the duration of action potential
- Awould be longer
- Bwould be shorter
- Cwould be the same
- Dwould be the same but with no relative refractory period
- Ethere would be relative refractory period only.
9What would happen to a muscle action potential if 50% of the sodium channels are 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
10Postsynaptic density (opacity) is due to the presence of ______ in the membrane:
- Amitochondria
- Bmyelin
- Creceptors
- Dsynaptic vesicles
- Eall of the above
11Multiple sclerosis (MS):
- Alesions are more diffused than they are in ALS
- Boccurs both in the CNS and the PNS
- Cis commonly known as Lou Gehrig’s disease
- Doccurs in the PNS only
- Enone of the above
12The resting membrane potential of a nerve is:
- Aless negative when Na+ concentration in extracellular fluid [Na]o is decreased
- Bmore negative when [K+]o is increased
- Cmore negative when [Na+]o is increased
- Dmore negative when [Ca2+]o is increased
- Enone of the above
13Which of the following statement(s) is/are True?
- ACompound action potentials are seen only when a nerve bundle containing a large number of axons of different conduction velocities is stimulated
- BExtracellular fluid contains more Ca2+ than intracellular fluid
- CTransfer of electrical signal across synapses is called transmission, whereas
travel of signal along axons is called conduction - Dspecific Na+ channels are not the same as acetylcholine channels.
- Eall of the above
14The inhibitory postsynaptic potential (IPSP):
- Ais the result of positive ions moving through ligand-gated channels
- Bhas a brief refractory period
- Cis propagated
- Dis the cause of stimulus artifact
- Enone of the above
15The 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 1 & 2
- Echoices 2 & 3
16Long-term potentiation (LTP)
- Ais a form of structural synaptic plasticity
- Bis manifested as an increase in synaptic strength (i.e. increased EPSP)
- Cis same a perforated synapses
- Dchoices 1 & 2
- Echoices 1, 2 & 3
17Depolarization of the terminal button leads to release of neurotransmitter in the following way:
- Aneurotransmitter in the neuroplasm diffuses across the terminal membrane through the synaptic cleft and onto the postsynaptic membrane.
- Bthe vesicles are released into the synaptic cleft where they diffuse and fuse into the postsynaptic membrane.
- Cneurotransmitter diffuses through gap junction from the presynaptic to postsynaptic membrane
- Dnone of the above
18Presynaptic inhibition:
- Arequires longer time to develop
- Blasts longer
- Call types result in decreased neurotransmitter release
- Dchoices 1 & 2
- Echoices 1, 2 & 3
19While studying the transport of molecule B 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 B is further increased, the rate becomes constant. Based on this information, which of the following statements best describe this situation?
- Amolecule B is transported from outside to the cytoplasm.
- Bthe transport process involves a carrier protein.
- Cthe system exhibits saturation.
- Dchoices 1 & 2
- Echoices 1, 2 & 3
20A man falls into deep sleep with one arm under his head. This arm is paralyzed when he awakens, but it tingles, and he can feel pain sensation in it. The reason for the loss of motor function without loss of pain sensation is that:
- AA fibers are more susceptible to hypoxia than B fibers
- BA fibers are more susceptible to pressure than B fibers
- CA fibers are more susceptible to hypoxia than C fibers
- DA fibers are more susceptible to pressure than C fibers
21Which of the following statement(s) is/are False?
- Acompound action potential is seen when a single axon is stimulated
- BSchwann cells provide myelin for CNS nerve axons
- Ca compound action potential is an all-or-none phenomenon
- Dchoices 1 and 2
- Echoices 1, 2 and 3
22When an action potential depolarizes a terminal button, Ca2+:
- Aenters the synaptic vesicles
- Bis released into the synaptic cleft
- Centers the terminal button
- Denters the postsynaptic membrane to generate an EPSP
- Egenerates the coated vesicles
23Presynaptic facilitation (i.e. increased transmitter release) occurs when:
- Aextracellular concentration of sodium increases
- Bextracellular concentration of potassium increases
- Ccalcium channels in the presynaptic membrane are inhibited
- Dcalcium channels in the presynaptic membrane remain open longer
- Etemporal summation occurs
24Myelination:
- Aoccurs only in A type nerve axon
- Bof the dendrites (unlike axons) continues uninterrupted (no nodes of Ranvier)
- Caction potentials occur at the nodes of Ranvier along the axon
- Dchoices 1 and 3
- Echoices 2 and 3
25In the CNS, a severed or injured axon undergoes 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 1 and 2
- Echoices 1, 2 and 3
26Which of the following comparisons between neurons and muscle tissue is incorrect?
- Aresting potentials are greater in muscle fibers
- Bmuscle fibers conduct action potentials at relatively slower speeds
- Caction potentials last longer in muscle fibers
- Dmuscle fibers conduct action potentials only by saltatory conduction
27How would the ventricular muscle action potential be affected if calcium channels were blocked?
- Ait would look like a pacemaker action potential
- Bit would look like a nerve action potential
- Cit would be the same
- Dit would be the same but with no absolute refractory period
- Enone of the above
28The generation of an action potential occurs when the following the main steps take place:
a. sodium channels are inactivated
b. voltage-regulated potassium channels open and potassium moves out of the
cell initiating repolarization
c. sodium channels regain their normal properties
d. a graded depolarization brings an area of an excitable membrane to threshold
e. a temporary hyperpolarization occurs
f. sodium channel activation occurs
g. sodium ions enter the cell and depolarization occurs,
the proper sequence of event is:- Ad, f, g, c, b, e, a
- Bd, f, g, a, b, c, e
- Cf, g, d, a, b, c, e
- Db, d, f, g, a, c, e
- Ed, b, e, f, g, c, a
29Lysosomes are stabilized by:
- Aasbestos
- Bendomethacin
- Chigh vitamin A intake
- Dchoices 1 & 2
- Echoices 2 & 3
30Action potential is recorded from a length of squid axon that has a conduction velocity of 100 m/sec; the latent period is 1 msec and the amplitude of the action potential is 100mV. With this information in hand the length of the axon must be:
- A1 cm
- B5 cm
- C10 cm
- D100 cm
- Enot enough information is provided to make this determination
31synaptic transmission decreases when:
- Aa calcium ion chelating agent is present
- Bpostsynaptic receptors are blocked
- Cthe RMP of the presynaptic terminal is slightly (e.g. 3-5 mV) more negative
- Dchoices 1 & 2
- Echoices 2 & 3
32About Receptors:
- Aionotropic receptors exist only on postsynaptic membrane
- Bmetabotropic receptors exist only on presynaptic membrane
- Cmetabotropic receptors, which are G-protein coupled, exist on postsynaptic membrane of fast synapses
- Dionotropic receptors, which are not G-protein coupled, exist on postsynaptic membrane of fast synapses
- Enone of the above
33The All-or-nothing rule applies to:
- AIPSP
- BmEPP
- CEPSP
- DEPP
- Enone of the above
34IPSPs:
- Aresult in local depolarizations
- Bresult in local hyperpolarizations
- Cincrease membrane permeability to sodium ions
- Dprevent the efflux of potassium ions
- Eprevent the efflux of calcium ions
35When a second EPSP arrives at a single synapse before the effects of the first have disappeared, what occurs is:
- Aspatial summation
- Btemporal summation
- Cinhibition of the action potential
- Dhyperpolarization
36Exocytosis is involved in:
- Aneurotransmitter release
- Baction of dynein and kinesin
- Csimple diffusion
- Dactive transport
- Enone of the above
37Which of the following is not normally embedded in the plasma membrane?
- Aneurotransmitter receptors e.g. ACh receptors
- BK+ channels
- CGlucose transporters in insulin-sensitive cells.
- DMicrotubules transporting synaptic vesicles
- Ethe Na-K pump
38The resting potential is due, in part, to the:
- Ainsulating effect of the Schwann cell
- Blarge negatively charged proteins on the outside
- Cactivity of the Na-K pump
- DNa+ equilibrium potential
- ECa2+ equilibrium potential
39Threshold for an action potential:
- Ais the same for different nerves
- Bis a measure of conduction velocity of the nerve
- Cthe higher it is the more excitable the nerve is.
- Dis dependent on the number of Na channels in the nerve; the higher the
number the lower the threshold. - EAll of the above.
40The amplitude of action potential in an axon is dependent on:
- Aextracellular Na+
- Bextracellular K+
- Cintracellular Ca2+
- Dextracellular Cl-
- Enone of the above
Información
- Descripción
- practice
- Autor
- Justin Miller
- Idioma
- English
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