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Justin Miller
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Practice Exam 2

Frage 1 von 40

1

The Na/K transporter (pump) is blocked by:

Wähle eine der folgenden:

  • TTX

  • local anesthetics

  • TEA

  • none of the above

  • all of the above

Erklärung

Frage 2 von 40

1

nAChR channels at the endplate:

Wähle eine der folgenden:

  • open when the endplate is depolarized

  • are non-selective in that they allow positive and negative ions to pass through

  • ions pass through them by simple diffusion

  • open when serotonin or glutamate is present

  • none of the above

Erklärung

Frage 3 von 40

1

Axons 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:

Wähle eine der folgenden:

  • axon X is faster conducting than Y

  • axon Y is faster conducting than X

  • axons X and Y have equal conduction velocity

  • axon X save more energy than axon Y

  • axons X and Y save same amount of energy

Erklärung

Frage 4 von 40

1

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: (hint: log 10=1)

Wähle eine der folgenden:

  • a type of presynaptic inhibition results

  • the nerve terminal is depolarized

  • the incoming action potential is decreased in amplitude

  • the amount of transmitter released is less

  • All of the above

Erklärung

Frage 5 von 40

1

The fate of Na and K ions that enter and leave respectively during the action potential:

Wähle eine der folgenden:

  • Na ions exit through their channels just before they close

  • K ions enter through the delayed rectifier channels before they close

  • the Na/K pump returns the ions to their original concentrations

  • Na ions are trapped, but they slowly diffuse out across the membrane.

  • all of the above

Erklärung

Frage 6 von 40

1

Which of the following statements is/are incorrect:

Wähle eine der folgenden:

  • alkalosis can cause excitation of the CNS

  • termination of epileptic seizures can be due to Wedensky inhibition

  • in the Renshaw circuit activity of one motor neuron result in self-inhibition as well as inhibition of an antagonist second motor neuron

  • removal of Ca from the vicinity of a synapse causes increased excitability of the axon but also causes inhibition of synaptic transmission

  • none of the above

Erklärung

Frage 7 von 40

1

Which of the following statements is/are incorrect:

Wähle eine der folgenden:

  • the motor endplate is electrically not excitable

  • pinocytosis is the reverse of phagocytosis

  • demarcation (injury) potential is a monophasic action potential

  • water is a polar molecule but can cross the cell membrane freely

  • all of the above

Erklärung

Frage 8 von 40

1

If the voltage-regulated sodium channels failed to become inactivated, then the duration of action potential

Wähle eine der folgenden:

  • would be longer

  • would be shorter

  • would be the same

  • would be the same but with no relative refractory period

  • there would be relative refractory period only.

Erklärung

Frage 9 von 40

1

What would happen to a muscle action potential if 50% of the sodium channels are blocked?

Wähle eine der folgenden:

  • 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

Erklärung

Frage 10 von 40

1

Postsynaptic density (opacity) is due to the presence of ______ in the membrane:

Wähle eine der folgenden:

  • mitochondria

  • myelin

  • receptors

  • synaptic vesicles

  • all of the above

Erklärung

Frage 11 von 40

1

Multiple sclerosis (MS):

Wähle eine der folgenden:

  • lesions are more diffused than they are in ALS

  • occurs both in the CNS and the PNS

  • is commonly known as Lou Gehrig’s disease

  • occurs in the PNS only

  • none of the above

Erklärung

Frage 12 von 40

1

The resting membrane potential of a nerve is:

Wähle eine der folgenden:

  • less negative when Na+ concentration in extracellular fluid [Na]o is decreased

  • more negative when [K+]o is increased

  • more negative when [Na+]o is increased

  • more negative when [Ca2+]o is increased

  • none of the above

Erklärung

Frage 13 von 40

1

Which of the following statement(s) is/are True?

Wähle eine der folgenden:

  • Compound action potentials are seen only when a nerve bundle containing a large number of axons of different conduction velocities is stimulated

  • Extracellular fluid contains more Ca2+ than intracellular fluid

  • Transfer of electrical signal across synapses is called transmission, whereas
    travel of signal along axons is called conduction

  • specific Na+ channels are not the same as acetylcholine channels.

  • all of the above

Erklärung

Frage 14 von 40

1

The inhibitory postsynaptic potential (IPSP):

Wähle eine der folgenden:

  • is the result of positive ions moving through ligand-gated channels

  • has a brief refractory period

  • is propagated

  • is the cause of stimulus artifact

  • none of the above

Erklärung

Frage 15 von 40

1

The refractory periods (RP):

Wähle eine der folgenden:

  • 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 1 & 2

  • choices 2 & 3

Erklärung

Frage 16 von 40

1

Long-term potentiation (LTP)

Wähle eine der folgenden:

  • is a form of structural synaptic plasticity

  • is manifested as an increase in synaptic strength (i.e. increased EPSP)

  • is same a perforated synapses

  • choices 1 & 2

  • choices 1, 2 & 3

Erklärung

Frage 17 von 40

1

Depolarization of the terminal button leads to release of neurotransmitter in the following way:

Wähle eine der folgenden:

  • neurotransmitter in the neuroplasm diffuses across the terminal membrane through the synaptic cleft and onto the postsynaptic membrane.

  • the vesicles are released into the synaptic cleft where they diffuse and fuse into the postsynaptic membrane.

  • neurotransmitter diffuses through gap junction from the presynaptic to postsynaptic membrane

  • none of the above

Erklärung

Frage 18 von 40

1

Presynaptic inhibition:

Wähle eine der folgenden:

  • requires longer time to develop

  • lasts longer

  • all types result in decreased neurotransmitter release

  • choices 1 & 2

  • choices 1, 2 & 3

Erklärung

Frage 19 von 40

1

While 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?

Wähle eine der folgenden:

  • molecule B is transported from outside to the cytoplasm.

  • the transport process involves a carrier protein.

  • the system exhibits saturation.

  • choices 1 & 2

  • choices 1, 2 & 3

Erklärung

Frage 20 von 40

1

A 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:

Wähle eine der folgenden:

  • A fibers are more susceptible to hypoxia than B fibers

  • A fibers are more susceptible to pressure than B fibers

  • A fibers are more susceptible to hypoxia than C fibers

  • A fibers are more susceptible to pressure than C fibers

Erklärung

Frage 21 von 40

1

Which of the following statement(s) is/are False?

Wähle eine der folgenden:

  • compound action potential is seen when a single axon is stimulated

  • Schwann cells provide myelin for CNS nerve axons

  • a compound action potential is an all-or-none phenomenon

  • choices 1 and 2

  • choices 1, 2 and 3

Erklärung

Frage 22 von 40

1

When an action potential depolarizes a terminal button, Ca2+:

Wähle eine der folgenden:

  • enters the synaptic vesicles

  • is released into the synaptic cleft

  • enters the terminal button

  • enters the postsynaptic membrane to generate an EPSP

  • generates the coated vesicles

Erklärung

Frage 23 von 40

1

Presynaptic facilitation (i.e. increased transmitter release) occurs when:

Wähle eine der folgenden:

  • extracellular concentration of sodium increases

  • extracellular concentration of potassium increases

  • calcium channels in the presynaptic membrane are inhibited

  • calcium channels in the presynaptic membrane remain open longer

  • temporal summation occurs

Erklärung

Frage 24 von 40

1

Myelination:

Wähle eine der folgenden:

  • occurs only in A type nerve axon

  • of the dendrites (unlike axons) continues uninterrupted (no nodes of Ranvier)

  • action potentials occur at the nodes of Ranvier along the axon

  • choices 1 and 3

  • choices 2 and 3

Erklärung

Frage 25 von 40

1

In the CNS, a severed or injured axon undergoes Wallerian degeneration but virtually no regeneration takes place because:

Wähle eine der folgenden:

  • 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 1 and 2

  • choices 1, 2 and 3

Erklärung

Frage 26 von 40

1

Which of the following comparisons between neurons and muscle tissue is incorrect?

Wähle eine der folgenden:

  • resting potentials are greater in muscle fibers

  • muscle fibers conduct action potentials at relatively slower speeds

  • action potentials last longer in muscle fibers

  • muscle fibers conduct action potentials only by saltatory conduction

Erklärung

Frage 27 von 40

1

How would the ventricular muscle action potential be affected if calcium channels were blocked?

Wähle eine der folgenden:

  • it would look like a pacemaker action potential

  • it would look like a nerve action potential

  • it would be the same

  • it would be the same but with no absolute refractory period

  • none of the above

Erklärung

Frage 28 von 40

1

The 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:

Wähle eine der folgenden:

  • d, f, g, c, b, e, a

  • d, f, g, a, b, c, e

  • f, g, d, a, b, c, e

  • b, d, f, g, a, c, e

  • d, b, e, f, g, c, a

Erklärung

Frage 29 von 40

1

Lysosomes are stabilized by:

Wähle eine der folgenden:

  • asbestos

  • endomethacin

  • high vitamin A intake

  • choices 1 & 2

  • choices 2 & 3

Erklärung

Frage 30 von 40

1

Action 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:

Wähle eine der folgenden:

  • 1 cm

  • 5 cm

  • 10 cm

  • 100 cm

  • not enough information is provided to make this determination

Erklärung

Frage 31 von 40

1

synaptic transmission decreases when:

Wähle eine der folgenden:

  • a calcium ion chelating agent is present

  • postsynaptic receptors are blocked

  • the RMP of the presynaptic terminal is slightly (e.g. 3-5 mV) more negative

  • choices 1 & 2

  • choices 2 & 3

Erklärung

Frage 32 von 40

1

About Receptors:

Wähle eine der folgenden:

  • ionotropic receptors exist only on postsynaptic membrane

  • metabotropic receptors exist only on presynaptic membrane

  • metabotropic receptors, which are G-protein coupled, exist on postsynaptic membrane of fast synapses

  • ionotropic receptors, which are not G-protein coupled, exist on postsynaptic membrane of fast synapses

  • none of the above

Erklärung

Frage 33 von 40

1

The All-or-nothing rule applies to:

Wähle eine der folgenden:

  • IPSP

  • mEPP

  • EPSP

  • EPP

  • none of the above

Erklärung

Frage 34 von 40

1

IPSPs:

Wähle eine der folgenden:

  • result in local depolarizations

  • result in local hyperpolarizations

  • increase membrane permeability to sodium ions

  • prevent the efflux of potassium ions

  • prevent the efflux of calcium ions

Erklärung

Frage 35 von 40

1

When a second EPSP arrives at a single synapse before the effects of the first have disappeared, what occurs is:

Wähle eine der folgenden:

  • spatial summation

  • temporal summation

  • inhibition of the action potential

  • hyperpolarization

Erklärung

Frage 36 von 40

1

Exocytosis is involved in:

Wähle eine der folgenden:

  • neurotransmitter release

  • action of dynein and kinesin

  • simple diffusion

  • active transport

  • none of the above

Erklärung

Frage 37 von 40

1

Which of the following is not normally embedded in the plasma membrane?

Wähle eine der folgenden:

  • neurotransmitter receptors e.g. ACh receptors

  • K+ channels

  • Glucose transporters in insulin-sensitive cells.

  • Microtubules transporting synaptic vesicles

  • the Na-K pump

Erklärung

Frage 38 von 40

1

The resting potential is due, in part, to the:

Wähle eine der folgenden:

  • insulating effect of the Schwann cell

  • large negatively charged proteins on the outside

  • activity of the Na-K pump

  • Na+ equilibrium potential

  • Ca2+ equilibrium potential

Erklärung

Frage 39 von 40

1

Threshold for an action potential:

Wähle eine der folgenden:

  • is the same for different nerves

  • is a measure of conduction velocity of the nerve

  • the higher it is the more excitable the nerve is.

  • is dependent on the number of Na channels in the nerve; the higher the
    number the lower the threshold.

  • All of the above.

Erklärung

Frage 40 von 40

1

The amplitude of action potential in an axon is dependent on:

Wähle eine der folgenden:

  • extracellular Na+

  • extracellular K+

  • intracellular Ca2+

  • extracellular Cl-

  • none of the above

Erklärung