,Test Bank: Lippincott Illustrated Reviews:
Neuroscience
Second Edition
Krebs, Weinberg, Akesson & Dilli
,Table of Contents
Chapter 1: Introduction to the Nervous System and Basic
Neurophysiology
Chapter 2: Overview of the Central Nervous System
Chapter 3: Overview of the Peripheral Nervous System
Chapter 4: Overview of the Visceral Nervous System
Chapter 5: The Spinal Cord
Chapter 6: Overview and Organization of the Brainstem
Chapter 7: Ascending Sensory Tracts
Chapter 8: Descending Motor Tracts
Chapter 9: Control of Eye Movements
Chapter 10: Sensory and Motor Innervation of the Head and Neck
Chapter 11: Hearing and Balance
Chapter 12: Brainstem Systems and Review
Chapter 13: The Cerebral Cortex
Chapter 14: The Thalamus
Chapter 15: The Visual System
Chapter 16: The Cerebellum
Chapter 17: The Basal Ganglia
Chapter 18: The Hypothalamus
Chapter 19: The Limbic System
Chapter 20: The Cerebrospinal Fluid System
Chapter 21: The Blood Supply of the Brain and Spinal Cord
Chapter 22: Development of the Nervous System
,Chapter 1: Introduction to the Nervous System and Basic
Neurophysiology
Chapter Summary
Chapter 1 provides a foundational overview of the nervous system's
organization and the cellular mechanisms that underlie neural function.
It introduces the primary cell types: neurons (the signaling units) and
glia (supporting cells like astrocytes, oligodendrocytes, and microglia).
The chapter details the structure of a neuron, including the cell body,
dendrites, and axon. A significant portion is dedicated to
neurophysiology, explaining the resting membrane potential, the ionic
basis of the action potential (involving sodium and potassium channels),
and the mechanisms of synaptic transmission. It distinguishes between
electrical and chemical synapses and describes the process of
neurotransmitter release, receptor binding, and signal termination. This
chapter sets the stage for understanding how information is processed
and transmitted throughout the complex networks of the brain and
body.
Multiple Choice Questions (MCQs)
1. Which of the following glial cells is responsible for forming the
myelin sheath around axons in the Central Nervous System (CNS)?
A. Schwann cells
B. Astrocytes
C. Oligodendrocytes
D. Microglia
,Correct Answer: C
Rationale: Oligodendrocytes are the myelinating cells of the CNS. A
single oligodendrocyte can provide myelin for segments of multiple
axons. In contrast, Schwann cells perform this function in the Peripheral
Nervous System (PNS), with each Schwann cell myelinating only a single
axon segment. Astrocytes provide metabolic support and maintain the
blood-brain barrier, while microglia act as the resident immune cells of
the brain.
2. The "Resting Membrane Potential" of a typical neuron is
approximately -70 mV. This potential is primarily maintained by
the unequal distribution of which ions across the cell membrane?
A. Sodium (Na+) and Chloride (Cl-)
B. Potassium (K+) and Sodium (Na+)
C. Calcium (Ca2+) and Magnesium (Mg2+)
D. Potassium (K+) and Calcium (Ca2+)
Correct Answer: B
Rationale: The resting membrane potential is largely determined by
the high permeability of the membrane to Potassium (K+) ions and the
action of the Na+/K+ ATPase pump, which actively transports 3 Na+
ions out of the cell for every 2 K+ ions brought in. This creates a high
concentration of K+ inside and a high concentration of Na+ outside,
resulting in a negative charge inside the neuron relative to the outside.
,3. During the "Depolarization" phase of an action potential, which
of the following events occurs?
A. Voltage-gated K+ channels open, and K+ leaves the cell.
B. Voltage-gated Na+ channels open, and Na+ enters the cell.
C. The Na+/K+ pump stops working.
D. The membrane becomes more negative.
Correct Answer: B
Rationale: Depolarization is triggered when the membrane potential
reaches a threshold, causing voltage-gated Na+ channels to open
rapidly. Because of the electrochemical gradient, Na+ rushes into the
cell, making the interior more positive. This is the "upstroke" of the
action potential.
4. "Saltatory Conduction" refers to the process where an action
potential:
A. Travels slowly down an unmyelinated axon.
B. "Jumps" from one Node of Ranvier to the next in a myelinated axon.
C. Is transmitted backward toward the dendrites.
D. Occurs only in the cell body.
Correct Answer: B
Rationale: In myelinated axons, the insulating myelin prevents ion flow
across the membrane except at the gaps called Nodes of Ranvier. This
,allows the action potential to skip the myelinated sections and
regenerate only at the nodes, significantly increasing the speed of nerve
impulse conduction compared to unmyelinated fibers.
5. At a "Chemical Synapse," the release of neurotransmitters from
the presynaptic terminal is directly triggered by an influx of which
ion?
A. Sodium (Na+)
B. Potassium (K+)
C. Calcium (Ca2+)
D. Chloride (Cl-)
Correct Answer: C
Rationale: When an action potential reaches the presynaptic terminal,
it opens voltage-gated Calcium (Ca2+) channels. The resulting influx of
Ca2+ triggers the fusion of synaptic vesicles with the presynaptic
membrane, releasing neurotransmitters into the synaptic cleft via
exocytosis.
6. An "Excitatory Postsynaptic Potential" (EPSP) typically results
from the opening of channels that allow the influx of:
A. Potassium (K+)
B. Chloride (Cl-)
C. Sodium (Na+)
,D. Both B and C
Correct Answer: C
Rationale: An EPSP is a local depolarization of the postsynaptic
membrane that brings the neuron closer to the threshold for firing an
action potential. This is usually caused by the opening of ligand-gated
cation channels (like glutamate receptors) that allow Na+ to enter the
cell.
7. "Microglia" are unique among CNS glia because they:
A. Form the blood-brain barrier.
B. Are derived from yolk sac macrophages and function as the brain's
immune system.
C. Provide structural support to neurons.
D. Produce cerebrospinal fluid.
Correct Answer: B
Rationale: Microglia are the resident macrophages of the CNS. Unlike
other glia (astrocytes, oligodendrocytes) which are of ectodermal origin,
microglia originate from hematopoietic stem cells in the yolk sac. They
migrate into the brain during development and act as scavengers,
removing debris and responding to injury or infection.
8. The "Absolute Refractory Period" is a time during which:
A. A second action potential can be triggered by a very strong stimulus.
,B. No second action potential can be triggered, regardless of the
stimulus strength, because Na+ channels are inactivated.
C. The neuron is hyperpolarized.
D. The neuron is at its resting potential.
Correct Answer: B
Rationale: During the absolute refractory period, which occurs
immediately after the peak of the action potential, the voltage-gated Na+
channels are in an inactivated state and cannot be reopened. This
ensures that action potentials are discrete events and travel in only one
direction down the axon.
9. "Astrocytes" play a critical role in the CNS by:
A. Myelinating axons.
B. Regulating the extracellular environment, including the uptake of
excess K+ and neurotransmitters like glutamate.
C. Acting as the primary excitatory neurons.
D. Conducting action potentials.
Correct Answer: B
Rationale: Astrocytes are the most numerous glia in the brain. They
have many functions, including providing metabolic support to neurons,
maintaining the blood-brain barrier, and "mopping up" excess ions and
neurotransmitters from the synaptic cleft to prevent excitotoxicity and
maintain proper signaling.
, 10. The "All-or-None" law of action potentials states that:
A. Larger stimuli produce larger action potentials.
B. An action potential either occurs completely (if threshold is reached)
or not at all, and its amplitude is constant.
C. Action potentials only occur in the brain.
D. All neurons fire at the same time.
Correct Answer: B
Rationale: Once a stimulus reaches the threshold potential, an action
potential is triggered. Increasing the strength of the stimulus does not
increase the size or speed of the action potential; it only increases the
*frequency* of firing. If the threshold is not reached, no action potential
occurs.
11. Which part of the neuron is typically the site where multiple
signals are integrated to "decide" whether to fire an action
potential?
A. The dendrites
B. The axon terminal
C. The axon hillock (Initial Segment)
D. The myelin sheath
Correct Answer: C
Neuroscience
Second Edition
Krebs, Weinberg, Akesson & Dilli
,Table of Contents
Chapter 1: Introduction to the Nervous System and Basic
Neurophysiology
Chapter 2: Overview of the Central Nervous System
Chapter 3: Overview of the Peripheral Nervous System
Chapter 4: Overview of the Visceral Nervous System
Chapter 5: The Spinal Cord
Chapter 6: Overview and Organization of the Brainstem
Chapter 7: Ascending Sensory Tracts
Chapter 8: Descending Motor Tracts
Chapter 9: Control of Eye Movements
Chapter 10: Sensory and Motor Innervation of the Head and Neck
Chapter 11: Hearing and Balance
Chapter 12: Brainstem Systems and Review
Chapter 13: The Cerebral Cortex
Chapter 14: The Thalamus
Chapter 15: The Visual System
Chapter 16: The Cerebellum
Chapter 17: The Basal Ganglia
Chapter 18: The Hypothalamus
Chapter 19: The Limbic System
Chapter 20: The Cerebrospinal Fluid System
Chapter 21: The Blood Supply of the Brain and Spinal Cord
Chapter 22: Development of the Nervous System
,Chapter 1: Introduction to the Nervous System and Basic
Neurophysiology
Chapter Summary
Chapter 1 provides a foundational overview of the nervous system's
organization and the cellular mechanisms that underlie neural function.
It introduces the primary cell types: neurons (the signaling units) and
glia (supporting cells like astrocytes, oligodendrocytes, and microglia).
The chapter details the structure of a neuron, including the cell body,
dendrites, and axon. A significant portion is dedicated to
neurophysiology, explaining the resting membrane potential, the ionic
basis of the action potential (involving sodium and potassium channels),
and the mechanisms of synaptic transmission. It distinguishes between
electrical and chemical synapses and describes the process of
neurotransmitter release, receptor binding, and signal termination. This
chapter sets the stage for understanding how information is processed
and transmitted throughout the complex networks of the brain and
body.
Multiple Choice Questions (MCQs)
1. Which of the following glial cells is responsible for forming the
myelin sheath around axons in the Central Nervous System (CNS)?
A. Schwann cells
B. Astrocytes
C. Oligodendrocytes
D. Microglia
,Correct Answer: C
Rationale: Oligodendrocytes are the myelinating cells of the CNS. A
single oligodendrocyte can provide myelin for segments of multiple
axons. In contrast, Schwann cells perform this function in the Peripheral
Nervous System (PNS), with each Schwann cell myelinating only a single
axon segment. Astrocytes provide metabolic support and maintain the
blood-brain barrier, while microglia act as the resident immune cells of
the brain.
2. The "Resting Membrane Potential" of a typical neuron is
approximately -70 mV. This potential is primarily maintained by
the unequal distribution of which ions across the cell membrane?
A. Sodium (Na+) and Chloride (Cl-)
B. Potassium (K+) and Sodium (Na+)
C. Calcium (Ca2+) and Magnesium (Mg2+)
D. Potassium (K+) and Calcium (Ca2+)
Correct Answer: B
Rationale: The resting membrane potential is largely determined by
the high permeability of the membrane to Potassium (K+) ions and the
action of the Na+/K+ ATPase pump, which actively transports 3 Na+
ions out of the cell for every 2 K+ ions brought in. This creates a high
concentration of K+ inside and a high concentration of Na+ outside,
resulting in a negative charge inside the neuron relative to the outside.
,3. During the "Depolarization" phase of an action potential, which
of the following events occurs?
A. Voltage-gated K+ channels open, and K+ leaves the cell.
B. Voltage-gated Na+ channels open, and Na+ enters the cell.
C. The Na+/K+ pump stops working.
D. The membrane becomes more negative.
Correct Answer: B
Rationale: Depolarization is triggered when the membrane potential
reaches a threshold, causing voltage-gated Na+ channels to open
rapidly. Because of the electrochemical gradient, Na+ rushes into the
cell, making the interior more positive. This is the "upstroke" of the
action potential.
4. "Saltatory Conduction" refers to the process where an action
potential:
A. Travels slowly down an unmyelinated axon.
B. "Jumps" from one Node of Ranvier to the next in a myelinated axon.
C. Is transmitted backward toward the dendrites.
D. Occurs only in the cell body.
Correct Answer: B
Rationale: In myelinated axons, the insulating myelin prevents ion flow
across the membrane except at the gaps called Nodes of Ranvier. This
,allows the action potential to skip the myelinated sections and
regenerate only at the nodes, significantly increasing the speed of nerve
impulse conduction compared to unmyelinated fibers.
5. At a "Chemical Synapse," the release of neurotransmitters from
the presynaptic terminal is directly triggered by an influx of which
ion?
A. Sodium (Na+)
B. Potassium (K+)
C. Calcium (Ca2+)
D. Chloride (Cl-)
Correct Answer: C
Rationale: When an action potential reaches the presynaptic terminal,
it opens voltage-gated Calcium (Ca2+) channels. The resulting influx of
Ca2+ triggers the fusion of synaptic vesicles with the presynaptic
membrane, releasing neurotransmitters into the synaptic cleft via
exocytosis.
6. An "Excitatory Postsynaptic Potential" (EPSP) typically results
from the opening of channels that allow the influx of:
A. Potassium (K+)
B. Chloride (Cl-)
C. Sodium (Na+)
,D. Both B and C
Correct Answer: C
Rationale: An EPSP is a local depolarization of the postsynaptic
membrane that brings the neuron closer to the threshold for firing an
action potential. This is usually caused by the opening of ligand-gated
cation channels (like glutamate receptors) that allow Na+ to enter the
cell.
7. "Microglia" are unique among CNS glia because they:
A. Form the blood-brain barrier.
B. Are derived from yolk sac macrophages and function as the brain's
immune system.
C. Provide structural support to neurons.
D. Produce cerebrospinal fluid.
Correct Answer: B
Rationale: Microglia are the resident macrophages of the CNS. Unlike
other glia (astrocytes, oligodendrocytes) which are of ectodermal origin,
microglia originate from hematopoietic stem cells in the yolk sac. They
migrate into the brain during development and act as scavengers,
removing debris and responding to injury or infection.
8. The "Absolute Refractory Period" is a time during which:
A. A second action potential can be triggered by a very strong stimulus.
,B. No second action potential can be triggered, regardless of the
stimulus strength, because Na+ channels are inactivated.
C. The neuron is hyperpolarized.
D. The neuron is at its resting potential.
Correct Answer: B
Rationale: During the absolute refractory period, which occurs
immediately after the peak of the action potential, the voltage-gated Na+
channels are in an inactivated state and cannot be reopened. This
ensures that action potentials are discrete events and travel in only one
direction down the axon.
9. "Astrocytes" play a critical role in the CNS by:
A. Myelinating axons.
B. Regulating the extracellular environment, including the uptake of
excess K+ and neurotransmitters like glutamate.
C. Acting as the primary excitatory neurons.
D. Conducting action potentials.
Correct Answer: B
Rationale: Astrocytes are the most numerous glia in the brain. They
have many functions, including providing metabolic support to neurons,
maintaining the blood-brain barrier, and "mopping up" excess ions and
neurotransmitters from the synaptic cleft to prevent excitotoxicity and
maintain proper signaling.
, 10. The "All-or-None" law of action potentials states that:
A. Larger stimuli produce larger action potentials.
B. An action potential either occurs completely (if threshold is reached)
or not at all, and its amplitude is constant.
C. Action potentials only occur in the brain.
D. All neurons fire at the same time.
Correct Answer: B
Rationale: Once a stimulus reaches the threshold potential, an action
potential is triggered. Increasing the strength of the stimulus does not
increase the size or speed of the action potential; it only increases the
*frequency* of firing. If the threshold is not reached, no action potential
occurs.
11. Which part of the neuron is typically the site where multiple
signals are integrated to "decide" whether to fire an action
potential?
A. The dendrites
B. The axon terminal
C. The axon hillock (Initial Segment)
D. The myelin sheath
Correct Answer: C
