Interactive Lecture Quiz

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Interactive Lecture Quiz 6 on Chapter 12-
Muscle

• Spring, 2008
• By Patricia L. Mansfield, Ph.D.
• Directions. Take this quiz using your powerpoint
  viewer to test yourself and to get immediate
  feedback on your answer choice.
• I obtained some figures, animations or videos
  from internet classes or from your textbook
  author to demonstrate the important principles
  covered in this quiz.

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4/14/2008
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Overview of Skeletal Muscle Anatomy Orders of
Magnitude
Figure 12-3a-1 ANATOMY SUMMARY Skeletal Muscle
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Skeletal Muscle Histology Orders of Magnitude
Figure 12-3a-2 ANATOMY SUMMARY Skeletal Muscle
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1. A motor unit consists of _____.a. one neuron
and the muscle fibers it controls.b. one nerve
and the skeletal muscles it controls.c. one
nerve and the body region it controls.d. one
neuron collateral and the one muscle fiber it
controls.

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1. A motor unit consists of _____.a. one neuron
and the muscle fibers it controls.b. one nerve
and the skeletal muscles it controls.c. one
nerve and the body region it controls.d. one
neuron collateral and the one muscle fiber it
controls.

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2. All muscle fibers in a single motor unit are
of the same fiber type, such as all fast-twitch
or all slow-twitch fibers.a. True b.
False
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3. Each of these statements is true, except one.
Identify the exception.a. The entire skeletal
muscle contracts in an all-or-none manner.b.
With endurance training, the metabolic
characteristics of muscle fibers can be changed
and enhanced.c. Each skeletal motor unit
contracts in an all-or-none manner.D. All muscle
fibers in a single motor unit are of the same
fiber type.e. A power muscle, such as in the
calf of the leg, may have 2,000 muscle fibers in
one motor unit.

• All-or-None or Graded Contractions
• Individual muscle fibers contract in an
  all-or-none fashion.
• On the other hand, whole muscle is capable of
  strong or weak contractions, depending upon how
  many muscle fibers are contracting at the same
  time.

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4. Put these neurons and myofibers in order of
recruitment from first to last.1. Highest
threshold neurons 2. Lowest threshold neurons
3. Higher threshold neurons4. Fatigue
resistant clow twitch fibers 5. Fatigue resistant
oxidative fast twitch fibers6. Glycolytic fast
twitch fibers

• Note for test-taking This is a flex question
  that requires the ordering of events!
• Notice that choices 1-3 list types of neurons
  and choices 4-6 list types of muscle fibers.
• Your goal is to decide which muscle fiber is
  fastest and which is slowest.
• The fastest muscle fiber MUST BE stimulated by
  the lowest threshold neurons.
• This strategy narrows your answer choice to C or
  E!

• 1, 6, 3, 5, 2, 4
• 1, 4, 3, 5, 2, 6
• 2, 4, 6, 1, 3, 5
• 3, 4, 1, 6, 2, 5
• 2, 4, 3, 5, 1, 6

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Recruitment of Fibers Produces Graduated Force

• Weak stimulus
• Lowest threshold fibers
• Slow twitch typically
• Moderate adds Fast Oxidative
• High stimulus all fibers
• Asynchronous
• Units take turns
• Prevents fatigue

Figure 12-18 Motor units
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5. When the myosin heads are loosely bound to the
actin filaments, the _____ span the space between
the parallel thick and thin filaments.a. nebulin
molecules b. sarcomeres c. calcium ionsd.
crossbridges e. tropomyosin molecules
http//interactivephysiology.com is the best way
to study the Sliding Filament Theory.
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6. The I band contains _____.a. thin
filaments b. an area of overlapping filaments
c. thick filaments d. all of these e. none of
these
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• 7. The H zone contains _____.
• thin filaments b. thick filaments
• c. an area of overlapping filaments
• d. all of these e. none of these

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Sarcomere Organization of FibersKnow the
position of all proteins.
Figure 12-6 Titin and nebulin
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• 8. A muscle can create force without becoming
  physically shorter.
• True b. False

Contrast isotonic versus isometric contraction.
Cross-bridge cycling must occur in both types of
contraction.
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9. Within a single skeletal muscle fiber, the
tension developed during a twitch depends on a.
the amount of neurotransmitter in the synapse. b.
the magnitude of the stimulus. c. the duration of
the stimulus. d. the length of the sarcomeres
prior to contraction. e. the force required to
move the relevant joint
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Know the facts in this table.
10. Smooth muscle cells lack which protein(s)? a.
troponin b. actin c. myosin d. tropomyosin
e. C and D
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11. Caveolae are important in smooth muscle
because they contain ___. a. voltage-regulated
Ca2 gates b. chemically-regulated Ca2
gates c. Enzymes to resist atherosclerosis d.
voltage-regulated Na gates e. A and B
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12. Which is true about cardiac muscle fibers? a.
Skeletal muscle fibers are shorter and have more
branches compared to cardiac fibers. b. They are
striated and have sarcomeres similar to skeletal
muscle fibers. c. Cardiac muscle fibers are
linked to each other by many gap junctions, like
single-unit smooth muscle d. all of these e. B
and C are true
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13. With the exception of the stomach, the wall
of the intestinal tract has ____ layers of smooth
muscle. a. 3 b. no c. 2 d. 1
Figure 21.2c
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• 14.Contraction of vascular smooth muscle is
  regulated by ___..
• hormones B. neurotransmitters c. Ca2
• d. paracrines E. all of these

Hormone
NT
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15. The enzyme of clinical importance that
becomes elevated in the event of damage to either
skeletal or cardiac muscle tissue is ____. a.
creatine phosphokinase (CPK) b. carbonic
anhydrase c. ATP synthase d. lactate
dehydrogenase e. none of these

• Per our studies of enzymes, and syllabus p.23
  use the class name of the enzyme to help you
  decide what it does. Use this process to narrow
  the enzyme choices.

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Answers
1. A 9. D 2. A 10. A 3. A 11. E 4. E 12.
E 5. D 13. C 6. A 14. E 7. B 15. A 8. A
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