Chapter 07 – The Peripheral Nervous System – Efferent Division
49. Most visceral organs are innervated by only parasympathetic nerve fibers.
a.
True
b.
False
False
50. Dual innervation of organs with nerve fibers whose actions oppose each other enables precise control over an organ’s
activity, like having both an accelerator and a brake to control the speed of a car.
a.
True
b.
False
True
51. Nicotinic receptors are activated by the tobacco plant derivative nicotine, whereas muscarinic receptors are activated
by the mushroom poison muscarine.
a.
True
b.
False
True
52. An antagonist binds with the receptor, preventing the neurotransmitter from binding and causing a response, yet the
antagonist itself produces no response.
a.
True
b.
False
True
53. The pons within the brain stem is the region most directly responsible for autonomic output.
a.
True
b.
False
False
54. Unlike the two-neuron chain of autonomic nerve fibers, the axon of a motor neuron is continuous from its origin in the
CNS to its ending on skeletal muscle.
a.
True
b.
False
True
55. Motor neurons are considered the final common pathway because the only way any other parts of the nervous system
can influence skeletal muscle activity is by acting on these motor neurons.
a.
True
b.
False
True
56. Amyotrophic lateral sclerosis (ALS) is also known as polio.
a.
True
b.
False
False
57. The result of infection with poliovirus is paralysis of the muscles innervated by the affected neurons.
a.
True
b.
False
True
58. Within a neuromuscular junction, the axon terminal splits into multiple fine branches, each of which ends in an
enlarged knoblike structure called the terminal button.
a.
True
b.
False
Chapter 07 – The Peripheral Nervous System – Efferent Division
True
59. The specialized underlying portion of the muscle cell membrane is called the sensory end plate.
a.
True
b.
False
False
60. Nerve and muscle cells do not come into direct contact at a neuromuscular junction.
a.
True
b.
False
61. The end-plate potential (EPP) is a graded potential similar to an EPSP, except that an EPP is much larger.
a.
True
b.
False
62. The motor end-plate region undergoes a threshold potential, so an action potential is initiated at this site.
a.
True
b.
False
63. The muscle cell’s electrical response is turned off by an enzyme in the motor end-plate membrane,
acetylcholinesterase (AChE), which inactivates ACh.
a.
True
b.
False
True
64. By removing relaxation-inducing ACh from the sensory end plate, AChE permits the choice of allowing relaxation to
take place or keeping the contraction going, depending on the body’s needs.
a.
True
b.
False
False
65. The agonist curare irreversibly binds to the Ach receptor-channels on the motor end plate.
a.
True
b.
False
False
junction
66. Skeletal muscle is innervated by the ____________________ nervous system, the branch of the
____________________ division subject to voluntary control.
67. Each autonomic nerve pathway extending from the CNS to an innervated organ is a(n) ____________________ chain.
two-neuron
68. Sympathetic nerve fibers originate in the ____________________ horn of the thoracic and lumbar regions of the
spinal cord.
lateral
69. The sympathetic ganglion chain is also called the sympathetic ____________________.
trunk
70. Long postganglionic fibers originate in the ____________________ chain and end on the ____________________
organs.
71. Parasympathetic preganglionic fibers are longer than sympathetic ____________________ fibers.
72. The sympathetic nervous system originates in the ____________________ regions of the spinal cord and has short
cholinergic preganglionic fibers and ____________________ adrenergic postganglionic fibers.
73. Most sympathetic postganglionic fibers are called ____________________ fibers because they release noradrenaline,
commonly known as norepinephrine.
74. Many autonomic fibers release ____________________ along with the classical neurotransmitters.
75. Autonomic efferent output regulates ____________________ activities such as circulation and digestion.
76. Sympathetic stimulation ____________________ the heart rate, whereas parasympathetic stimulation
____________________ it.
77. The parasympathetic system promotes ____________________ bodily functions while slowing down those activities
that are enhanced by the sympathetic system.
78. Nicotinic receptors are found on the ____________________ cell bodies in all autonomic ganglia.
79. Motor neurons, whose axons constitute the somatic nervous system, supply ____________________ muscles and
bring about movement.
80. Motor-neuron axon terminals release ____________________, which brings about excitation and contraction of the
innervated muscle cells.
81. Areas of the brain that exert control over skeletal muscle movements include the motor regions of the cortex, the
____________________ nuclei, the ____________________, and the brain stem.
82. The somatic system is under ____________________ control, but much of skeletal muscle activity involving posture,
balance, and stereotypical movements is coordinated ____________________.
83. The function of the afferent neuron is to carry information about the external and internal environments to the
____________________.
84. Within a neuromuscular junction, the axon terminal splits into multiple fine branches, each of which ends in an
enlarged knoblike structure called the ____________________.
85. ____________________ ions trigger the release of acetylcholine by exocytosis from a portion of the vesicles.
86. An action potential in a motor neuron is ____________________ to the terminal button.
87. A neuromuscular junction is always ____________________ (an EPP), whereas a synapse may be excitatory (an
EPSP) or inhibitory (an IPSP).
88. The muscle cell’s electrical response is turned off by an enzyme in the motor end-plate membrane called
____________________.
89. Death from organophosphates results from ____________________ failure because the ____________________
remains in a depolarization block and cannot be stimulated to contract again.
90. Myasthenia gravis is a(n) ____________________ condition in which the body erroneously produces antibodies
against its motor end-plate ____________________ receptor-channels.
Figure 7-5
Answer the following questions using the accompanying figure.
91. Which number in the figure represents motor neuron propagation?
a.
1
b.
2
Chapter 07 – The Peripheral Nervous System – Efferent Division
c.
3
d.
4
e.
5
f.
6
92. Which number in the figure shows ACh diffusing across the space separating the nerve and muscle cells and binding
with receptor-channels specific for it on the motor end plate of the muscle cell membrane?
a.
1
b.
2
c.
3
d.
4
e.
5
f.
6
d
93. Which number in the figure represents a local action potential triggering the opening of voltage-gated Ca2+ channels
and the subsequent entry of Ca2+ into the terminal button?
a.
1
b.
2
c.
3
d.
4
e.
5
f.
6
b
94. Which number in the figure represents an end-plate potential, where local current flows between the depolarized end
plate and the adjacent membrane?
a.
1
b.
2
Chapter 07 – The Peripheral Nervous System – Efferent Division
c.
3
d.
4
e.
5
f.
6
95. Which number in the figure represents the release of acetylcholine (ACh) by exocytosis from a portion of the vesicles?
a.
1
b.
2
c.
3
d.
4
e.
5
f.
6
96. Describe sympathetic dominance.
97. Give an exception to the general rule of dual reciprocal innervation by the autonomic nervous system.
98. Discuss the most common motor-neuron disease.
99. Discuss how organophosphates affect neuromuscular junctions.
100. Discuss how botulinum toxin can be used beneficially.