02: Nerve Function And Communication Flashcards

1
Q

Lecture review question: True or false: The basic function of a neuron is to receive information, integrate signals, to determine whether or not information should be passed along, and to communicate signals to target cells.

A

True

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2
Q

Lecture review question: Which of the following cations are found in higher concentrations outside of the cell? Select all that apply.

K+
Na+
Ca++
Cl-
OA-

A

Na+ and Ca++

Cations are positive and are found in higher concentrations OUTSIDE of the cell with the exception of K+, which is also a cation but is found INSIDE the cell.

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3
Q

Lecture review question: True or false: During active transport, a substance moves across the cell membrane due to “natural forces” requiring no energy expenditure from the cell.

A

False

Active transport requires energy to move the ions against the repelling force.

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4
Q

Lecture review question: Which of the following ion channels (transmembrane proteins) is important in establishing the resting membrane potential of neurons?

A. Leak channels
B. Voltage-gated ion channels
C. Ligand-gated ion channels
D. Signal-gated ion channels
E. Stress-gated ion channels

A

A

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5
Q

Lecture review question: Under resting conditions, which ions electrical force will cause the ion to move into the cell? Select all that apply.

Na+
K+
Ca++
Cl-
OA-

A

Na+, K+, Ca++

The principle of electrostatic pressure states that like charges will repel and unlike charges will attract; thus, all cations will move INTO the cell, as they are in higher concentrations OUTSIDE the cell.

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6
Q

Lecture review question: Under resting conditions, which ions chemical force will cause the ion to move out of the cell? Select all that apply.

Na+
K+
Ca++
Cl-
OA-

A

K+ and OA-

The principle of diffusion states that an ion will move from an area of higher concentration to lower; since K+ is higher INSIDE the cell, it will move OUTSIDE. NOTE: OA- concentration is also higher inside the cell, however, because the membrane is impermeable to OA-, it will actually be unable to move outside.

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7
Q

Lecture review question: Under resting conditions, which ions electrical and chemical driving forces are in the same direction? Select all that apply.

Na+
K+
Ca++
Cl-
OA-

A

Na+ and Ca++

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8
Q

Lecture review question: True or false: If membrane permeability increases (via the opening of ion channels) to Na+, it will move into the cell.

A

True

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9
Q

Lecture review question: True or false: When an ion reaches its equilibrium potential the electrical and chemical forces acting on the ion are equal and there is no net movement of the ion across the cell membrane.

A

True

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10
Q

Lecture review question: True or false: The resting membrane potential of a typical neuron approaches the equilibrium potential of Na+.

A

False

The resting membrane potential of a typical neuron approaches the equilibrium potential of K+.

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11
Q

Lecture review question: True or false: A graded potential is a very large fluctuation of the membrane potential that typically brings a neuron to its threshold potential.

A

False

A graded potential is a small fluctuation in the membrane potential caused by an excitatory or inhibitory input coming into a neuron.

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12
Q

Lecture review question: True or false: A change in the membrane potential from -70mV to -50 mV means the membrane is hyperpolarizing.

A

False

A change in the membrane potential from -70mV to -50 mV means the membrane is depolarization.

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13
Q

Lecture review question: True or false: A post-synaptic potential is generated by the binding of a neurotransmitter to a receptor.

A

True

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14
Q

Lecture review question: True or false: An inhibitory post-synaptic potential causes depolarization of the cell membrane.

A

False

An inhibitory post-synaptic potential causes membrane hyperpolarization, while an excitatory post-synaptic potential causes membrane depolarization.

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15
Q

Lecture review question: The opening of which of the following ligand-gated ion channels will result in the generation of IPSP? Select all that apply.

Na+
K+
Ca++
Cl-

A

K+ and Cl-

The chemical forces of K+ and Cl- are greater than their electrical forces; thus, if a channel is opened, K+ will diffuse out (Cl- would diffuse in).

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16
Q

Lecture review question: The additive effect of high frequency input of one pre-synaptic neuron on a post-synaptic neuron is called __________.

A. Spatial summation
B. Temporal summation
C. Integration

A

B

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17
Q

Lecture review question: True or false: The threshold potential is the membrane potential at which an action potential will be triggered.

A

True

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18
Q

Lecture review question: Depolarization of the initial segment of the axon causes the opening of which of the following ion channels?

A. Leak channels
B. Voltage-gated Na+ channels
C. Ligand-gated Na+ channels
D. Signal-gated Ca++ channels

A

B

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19
Q

Lecture review question: What causes the rising phase of the action potential?

A. Influx of K+
B. Influx Na+
C. Efflux of K+
D. Efflux of Na+

A

B

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20
Q

Lecture review question: True or false: The absolute refractory period is due to the inactivation of voltage-gated K+ channels.

A

False

The absolute refractory period is the period of time when another action potential cannot be triggered.

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21
Q

Lecture review question: True or false: As magnitude of a stimulus increases, the amplitude of the action potential increases.

A

False

An action potential is an all-or-none response. Its amplitude will remain the same regardless of the amount of stimulation coming into the neuron.

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22
Q

Lecture review question: True or false: Saltatory conduction is produced in myelinated axons.

A

True

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23
Q

Lecture review question: Which of the following axons will conduct action potentials with the greatest speed?

A. Small, myelinated axons
B. Large, myelinated axons
C. Small, unmyelinated axons

A

B

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24
Q

Lecture review question: Which ions are higher in concentration outside the cell?

A

Na+, Cl-, and Ca++

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25
Q

Lecture review question: Which ions’ chemical and electrical driving forces are in opposite directions?

A

K+ and Cl-

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26
Q

Lecture review question: If the cell membrane becomes more permeable to Na+, will Na+ move into or out of the cell?

A

Na+ is in greater concentration outside the cell, thus, it would move into the cell (to the lower concentration).

27
Q

Lecture review question: What are the differences between passive and active transport?

A

Passive transport does not require energy expenditure.

Active transport requires energy to move ions against force.

28
Q

Lecture review question: What causes the electrochemical driving forces that act on ions?

A

Electrostatic pressure (like charges repel unlike charges attract) and diffusion (high concentration moves toward low concentration) in order to achieve equilibrium potential.

29
Q

Lecture review question: What causes the resting membrane potential of a neuron?

A

The typical resting membrane potential of a neuron is negative (-70 mV). At rest, the cell membrane is much more permeable to K+, and thus, the membrane potential approaches the equilibrium potential for K+.

30
Q

Lecture review question: Do graded potentials increase in magnitude as the stimulus increases in magnitude?

A

Yes; the magnitude of the response is proportional to the strength of the stimulus.

31
Q

Lecture review question: What is meant by temporal and spatial summation?

A

Temporal summation is the additive effect of high-frequency input of one pre-synaptic neuron on a post-synaptic neuron.

Spatial summation is the additive effect of simultaneous stimulation from multiple pre-synpatic nerons on a post-synaptic neuron.

32
Q

Lecture review question: What determines if a neuron will fire an action potential?

A

The action potential is an explosion of electrical activity that is created by a depolarizing current. This means that some event (a stimulus) causes the resting potential to move toward 0 mV. When the depolarization reaches about -55 mV a neuron will fire an action potential.

33
Q

Lecture review question: What causes the rising and falling phases of the action potential?

A

An influx of Na+ causes the rising phase of an action potential, whereas the efflux of K+ via leak channels and voltage-gated K+ channels causes the falling phase.

34
Q

Lecture review question: Do action potentials increase in amplitude as the stimulus increases in magnitude?

A

An action potential is an all-or-none response. Its amplitude will remain the same regardless of the amount of stimulation coming into the neuron.

35
Q

Lecture review question: What is the function of myelin?

A

Myelin allows electrical impulses to transmit quickly and efficiently along the nerve cells.

36
Q

Which transmembrane protein channel is open all the time allowing for the passage of specific ions across the neuronal membrane?

A. Leakage channels
B. Voltage-gated channels
C. Ligand-gated channels
D. Signal-gated channels
E. Active transporters

A

A

Leak channels remain open all the time.

Voltage-gated channels open/close in response to membrane potential (electric).

Ligand-gated channels open/close when a neurotransmitter binds them (chemical).

Signal-gated channels open due to intracellular events.

Active transporters need ATP (energy) because they are moving ions against their chemical gradient (most important is Na+/K+ pump).

37
Q

Which ion’s chemical force causes it to move out of the cell, while its electrical force causes it to move into the cell?

A. Sodium (Na+)
B. Potassium (K+)
C. Chloride (Cl-)
D. Calcium (Ca++)

A

B

38
Q

Lecture review question: True or false: A chemical synapse involves a physical connection between the pre-synaptic neuron and postsynaptic neuron.

A

False

An electrical synapse involves a physical connection between the presynaptic neuron and postsynaptic neuron.

39
Q

Lecture review question: Which of the voltage-gated ion channels will open when an action potential arrives at the terminal of the presynaptic neuron?

A. Voltage-gated Na+ channels
B. Voltage-gated Ca++ channels
C. Voltage-gated K+ channels

A

B

40
Q

Lecture review question: An influx of Ca++ into the cell causes which of the following events to occur?

A. Release of neurotransmitter from the presynaptic cell
B. Removal of neurotransmitter from synaptic cleft
C. Depolarization of axon terminal
D. Binding of neurotransmitter to receptor

A

A

41
Q

Lecture review question: True or false: Inhibitory neurotransmitters are transmitters that move the membrane potential toward hyperpolarization.

A

True

42
Q

Lecture review question: True or false: The binding of a neurotransmitter to a receptor causes a graded potential (EPSP or IPSP).

A

True

43
Q

Lecture review question: Which of the following neurotransmitters is considered the chief excitatory neurotransmitter of the brain?

A. GABA
B. Glutamate
C. Glycine
D. Dopamine

A

B

GABA is the chief INHIBITORY neurotransmitter of the BRAIN.

Glycine is the chief INHIBITORY neurotransmitter of the BRAINSTEM and SPINAL CORD.

Dopamine can have excitatory OR inhibitory effects—same as serotonin.

44
Q

Lecture review question: Which of the following neurotransmitters is important for activation of muscle contractions?

A. Serotonin
B. Acetylcholine
C. GABA
D. Glycine

A

B

45
Q

Lecture review question: True or false: An ionotropic receptor is a ligand-gated receptor.

A

True

46
Q

Lecture review question: Which of the following receptors is involved in mediating complex biological responses such as gene expression?

A. Ionotropic receptor
B. Metabotropic receptor

A

B

47
Q

Lecture review question: Which of the following terms describes a drug that binds the main receptor binding site but doesn’t activate the receptor?

A. Agonist
B. Antagonist
C. Positive allosteric modulator
D. Negative allosteric modulator

A

B

An agonist binds at the site and activates the receptor.

A positive allosteric modulator binds a regulatory site and enhances activity of the neurotransmitter.

A negative allosteric modulator binds a regulatory site and decreases the activity of the neurotransmitter.

48
Q

Lecture review question: Which of the following processes results in desensitization? Select all that apply.

A. Receptor up-regulation
B. Receptor down-regulation
C. Sequestering of receptors
D. Strengthening of the coupling of the receptor with downstream signaling pathway

A

B, C, and D

49
Q

Lecture review question: What is the difference between an electrical and chemical synapse?

A

Electrical: Physical connection
Chemical: Involves neurotransmitters

50
Q

Lecture review question: Which voltage-gated ion channels must open in order for a neurotransmitter to be released from a pre-synaptic cell?

A

Calcium (Ca++)

51
Q

Lecture review question: What determines whether a synapse is excitatory or inhibitory?

A

The type of neurotransmitter used and the ion channel receptors they interact with

52
Q

Lecture review question: What is the difference between ionotropic and metabotropic receptor?

A

Ionotropic: Ligand-gated (chemical)

Metabotropic: Signal-gated (intracellular events)

53
Q

Lecture review question: Which neurotransmitters are considered the chief inhibitory neurotransmitters of the brain and spinal chord?

A
  • GABA
  • Glycine
54
Q

Lecture review question: Which neurotransmitters have both excitatory and inhibitory effects?

A
  • Serotonin
  • Glutamate (glutamate is primarily excitatory, though)
55
Q

Lecture review question: What is the difference between an agonist and a positive allosteric modulator?

A

Agonist: binds the same site (main receptor site) that the endogenous ligand binds – activates the receptor.

Positive allosteric modulation: enhances the activity of binding, but at a different site than the endogenous ligand.

56
Q

Lecture review question: Does receptor down-regulation result in sensitization or desensitization?

A

Desensitization

S.U.D.D.: Sequestering + Uncoupling + Down-regulation = Desensitization

C.U.R.S.: Coupling + Up-regulation + Receptor = Sensitization

57
Q

Lecture review question: Which neural network module will propagate excitation in the downstream neuron in the circuit?

A. Feedforward excitation
B. Feedback recurrent excitation
C. Feedforward inhibition
D. Feedback recurrent inhibition
E. Convergence
F. Divergence
H. Lateral inhibition

A

B

58
Q

Lecture review question: Which neural network module allows integrated information from one source to be distributed to multiple sources?

A. Feedforward excitation
B. Feedback recurrent excitation
C. Feedforward inhibition
D. Feedback recurrent inhibition
E. Convergence
F. Divergence
H. Lateral inhibition

A

F

59
Q

Which neural network module will propagate inhibition in the downstream neuron in the circuit?

A. Feedforward excitation
B. Feedback recurrent excitation
C. Feedforward inhibition
D. Feedback recurrent inhibition
E. Convergence
F. Divergence
H. Lateral inhibition

A

D

60
Q

Which neural network module allows integrated information from multiple sources to be distributed to one source?

A. Feedforward excitation
B. Feedback recurrent excitation
C. Feedforward inhibition
D. Feedback recurrent inhibition
E. Convergence
F. Divergence
H. Lateral inhibition

A

E

61
Q

Excitotoxicity, activation of degradative enzymes, and free radicals are the direct result from what aspect of the ischemic cascade?

A. Loss of blood supply –> no oxygen –> no ATP for aerobic metabolism
B. Na+/K+ pump stops working
C. Ca++ builds up in neuron
D. Mitochondrial break down

A

C

62
Q

Cytotoxic edema is the direct result from what aspect of the ischemic cascade?

A. Loss of blood supply –> no oxygen –> no ATP for aerobic metabolism
B. Na+/K+ pump stops working; Na+ builds up in neuron
C. Ca++ pump stops working; Ca++ builds up in neuron
D. Mitochondrial break down

A

B

63
Q

What are 2 reasons anaerobic metabolism is detrimental to the neuron cell?

A
  • Produces less energy than ATP (about 15x less)
  • Lactic acid production (in high quantity disrupts acid-base balance in the brain)
64
Q

What is the end result of ischemic cascade?

A. Neuronal death
B. Lactic acid production
C. Cytotoxic edema
D. Excitotoxicity

A

A