Question 1

What is the typical resting potential of an isolated neuron?

Accepted Answer

A)  -60 mV 
B)  -70 mV 
C)  -80 mV 
D)  -90 mV 
E)  100 mV 
A)  -60 mV 
B)  -70 mV 
C)  -80 mV 
D)  -90 mV 
E)  100 mV B

Question 2

Oligodendrocytes are responsible for myelinating central nervous system axons.

Accepted Answer

A) True 
 B)False  True

Question 3

Explain how neuron action potential propagation rate can be increased.

Accepted Answer

Neuron action potential propagation can be increased in two ways: (1) by increasing axonal diameter, and (2) myelinating the axon. Increased axonal diameter reduces electrical resistance to current flow. Myelination causes an electrical current to "jump" from one node of Ranvier to the next by saltatory conduction, which is more rapid than conduction in an unmyelinated neuron.

Question 4

The intensity of an electrical impulse is reflected in the ____ of action potentials.

Accepted Answer

A)  frequency 
B)  magnitude 
C)  duration 
D)  intensity 
E)  the frequency and duration 
A)  frequency 
B)  magnitude 
C)  duration 
D)  intensity 
E)  the frequency and duration

Question 5

Most neurons that release GABA and glycine are ____.

Accepted Answer

A)  astrocytes 
B)  projection neurons 
C)  interneurons 
D)  oligodendrocytes 
E)  Schwann cells 
A)  astrocytes 
B)  projection neurons 
C)  interneurons 
D)  oligodendrocytes 
E)  Schwann cells

Question 6

Place the events in chemical synapse transmission in the correct order. (1)   Ca2+enters axon terminal.
(2)  Ligand-gated ion channels open in postsynaptic membrane.
(3)   Neurotransmitter binds to postsynaptic receptor.
(4)   Action potential reaches axon terminal of presynaptic neuron.
(5)   Neurotransmitter released by exocytosis.

Accepted Answer

A)  4, 1, 5, 3, 2 
B)  4, 3, 1, 5, 2 
C)  4, 5, 1, 3, 2 
D)  4, 1, 3, 5, 2 
E)  4, 5, 2, 3, 1 
A)  4, 1, 5, 3, 2 
B)  4, 3, 1, 5, 2 
C)  4, 5, 1, 3, 2 
D)  4, 1, 3, 5, 2 
E)  4, 5, 2, 3, 1

Question 7

In an effort to determine the mechanism of neuronal signaling, Otto Loewi isolated ____.

Accepted Answer

A)  frog hearts 
B)  frog brains 
C)  rat hearts 
D)  rat brains 
E)  rat vagus nerve 
A)  frog hearts 
B)  frog brains 
C)  rat hearts 
D)  rat brains 
E)  rat vagus nerve

Question 8

Figure 39.1
-Answer the question using the accompanying figure. At which point in this action potential diagram does the onset of Na+channel inactivation stop the inward flow of Na+?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 9

Which process is responsible for the release of neurotransmitters from the presynaptic neuron into the synapse?

Accepted Answer

A)  diffusion 
B)  endocytosis 
C)  exocytosis 
D)  fusion 
E)  synaptic release 
A)  diffusion 
B)  endocytosis 
C)  exocytosis 
D)  fusion 
E)  synaptic release

Question 10

If the equilibrium potential is close to the resting membrane potential, the net ionic movement across the membrane will be very small.

Accepted Answer

A) True 
 B)False

Question 11

The additive effect of one neuron sending many EPSPs to another neuron over a brief period of time is called spatial summation .

Accepted Answer

A) True 
 B)False

Question 12

As the action potential peaks, ____.

Accepted Answer

A)  the activation gates of Na+channels close 
B)  the inactivation gates of Na+channels close 
C)  the activation gates of K+channels close 
D)  Na+/K+active transport pumps are activated 
A)  the activation gates of Na+channels close 
B)  the inactivation gates of Na+channels close 
C)  the activation gates of K+channels close 
D)  Na+/K+active transport pumps are activated

Question 13

Which neurotransmitter is most likely to be inhibitory?

Accepted Answer

A)  glutamate 
B)  dopamine 
C)  Substance P 
D)  GABA 
E)  acetylcholine 
A)  glutamate 
B)  dopamine 
C)  Substance P 
D)  GABA 
E)  acetylcholine

Question 14

A graded, subthreshold change in the postsynaptic membrane potential that moves it toward threshold is called a(n) ____.

Accepted Answer

A)  IPSP 
B)  hyperpolarization 
C)  EPSP 
D)  depolarization 
E)  repolarization 
A)  IPSP 
B)  hyperpolarization 
C)  EPSP 
D)  depolarization 
E)  repolarization

Question 15

Explain how the resting membrane potential and resting ion distributions are established in a neuron.

Accepted Answer

A resting membrane potential of -70 mV i

Question 16

Figure 39.1
-Answer the question using the accompanying figure. At which point in this action potential diagram does the K+channel close to stabilize the membrane potential?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 17

An action potential is propagated down an unmyelinated neuronal plasma membrane because it stimulates voltage-gated ____ channels adjacent to it. (Choose the most accurate answer.)

Accepted Answer

A)  Na+ 
B)  Ca2+ 
C)  K+ 
D)  Na+and Ca2+ 
E)  K+and Ca2+ 
A)  Na+ 
B)  Ca2+ 
C)  K+ 
D)  Na+and Ca2+ 
E)  K+and Ca2+

Question 18

Which neuronal structure has the greatest density of voltage-gated Na+channels, resulting in the lowest threshold potential along a neuron?

Accepted Answer

A)  dendrites 
B)  cell body 
C)  axon hillock 
D)  axon 
E)  axon terminals 
A)  dendrites 
B)  cell body 
C)  axon hillock 
D)  axon 
E)  axon terminals

Question 19

Where are most synapses formed?

Accepted Answer

A)  on the dendrites of postsynaptic neurons 
B)  on cell bodies 
C)  on axon terminals 
D)  on oligodendrocytes 
E)  on Schwann cells 
A)  on the dendrites of postsynaptic neurons 
B)  on cell bodies 
C)  on axon terminals 
D)  on oligodendrocytes 
E)  on Schwann cells

Question 20

Which cells assist and nourish neurons that transmit electrical signals?

Accepted Answer

A)  receptor cells 
B)  neurons 
C)  effector cells 
D)  glial cells 
E)  signal cells 
A)  receptor cells 
B)  neurons 
C)  effector cells 
D)  glial cells 
E)  signal cells

Exam 39: Information Flow and the Neuron

What is the typical resting potential of an isolated neuron?

Oligodendrocytes are responsible for myelinating central nervous system axons.

Explain how neuron action potential propagation rate can be increased.

The intensity of an electrical impulse is reflected in the ____ of action potentials.

Most neurons that release GABA and glycine are ____.

In an effort to determine the mechanism of neuronal signaling, Otto Loewi isolated ____.

Figure 39.1 -Answer the question using the accompanying figure. At which point in this action potential diagram does the onset of Na+channel inactivation stop the inward flow of Na+?

Which process is responsible for the release of neurotransmitters from the presynaptic neuron into the synapse?

If the equilibrium potential is close to the resting membrane potential, the net ionic movement across the membrane will be very small.

The additive effect of one neuron sending many EPSPs to another neuron over a brief period of time is called spatial summation .

As the action potential peaks, ____.

Which neurotransmitter is most likely to be inhibitory?

A graded, subthreshold change in the postsynaptic membrane potential that moves it toward threshold is called a(n) ____.

Explain how the resting membrane potential and resting ion distributions are established in a neuron.

Figure 39.1 -Answer the question using the accompanying figure. At which point in this action potential diagram does the K+channel close to stabilize the membrane potential?

An action potential is propagated down an unmyelinated neuronal plasma membrane because it stimulates voltage-gated ____ channels adjacent to it. (Choose the most accurate answer.)

Which neuronal structure has the greatest density of voltage-gated Na+channels, resulting in the lowest threshold potential along a neuron?

Where are most synapses formed?

Which cells assist and nourish neurons that transmit electrical signals?

Introduction to Biological Concepts and Research

Life, Chemistry, and Water

Biological Molecules: the Carbon Compounds of Life

Cells

Membranes and Transport

Energy, Enzymes, and Biological Reactions

Cellular Respiration: Harvesting Chemical Energy

Photosynthesis

Cell Communication

Cell Division and Mitosis

Meiosis: the Cellular Basis of Sexual Reproduction

Mendel, Genes, and Inheritance

Genes, Chromosomes, and Human Genetics

Dna Structure, Replication, and Organization

Gene Expression: From Dna to Protein

Regulation of Gene Expression

Bacterial and Viral Genetics

Dna Technology: Making and Using Genetically Altered Organisms, and Other Applications

Genomes and Proteomes

The Development of Evolutionary Thought

Microevolution: Genetic Changes Within Populations

Speciation

Paleobiology and Macroevolution

Systematic Biology: Phylogeny and Classification

The Origin of Life

Prokaryotes and Viruses

Protists

Seedless Plants

Seed Plants

Fungi

Animal Phylogeny, Acoelomates, and Protostomes

Deuterostomes: Vertebrates and Their Closest Relatives

The Plant Body

Transport in Plants

Plant Nutrition

Reproduction and Development in Flowering Plants

Plant Signals and Responses to the Environment

Introduction to Animal Organization and Physiology

Nervous Systems

Sensory Systems

The Endocrine System

Muscles, Bones, and Body Movements

The Circulatory System

Defenses Against Disease

Gas Exchange: the Respiratory System

Digestive Systems and Animal Nutrition

Regulating the Internal Environment: Osmoregulation, Excretion, and Thermoregulation

Animal Reproduction

Animal Development

Ecology and the Biosphere

Population Ecology

Population Interactions and Community Ecology

Ecosystems

Biodiversity and Conservation Biology

Animal Behavior

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Figure 39.1 -Answer the question using the accompanying figure. At which point in this action potential diagram does the onset of Na⁺channel inactivation stop the inward flow of Na⁺?

Figure 39.1 -Answer the question using the accompanying figure. At which point in this action potential diagram does the K⁺channel close to stabilize the membrane potential?

Which neuronal structure has the greatest density of voltage-gated Na⁺channels, resulting in the lowest threshold potential along a neuron?