Muscle Histology Block 2 Sem-1
- 1.
Questions 1-3 The response options for the next three items are the same. Each item will state the number of options to select. Choose exactly this number. For each of the following muscle types, select the appropriate description(s). Skeletal muscle (SELECT 2 OPTIONS)
- A.
T tubules are located at the Z disk
- B.
T tubules are located at the A-I interface
- C.
T tubules are lined by external lamina
- D.
T tubules are absent
- E.
Oxytocin triggers contraction
- F.
Possess(es) dyads
- G.
Possess(es) triads
- H.
Possess caveolae
- I.
Troponin is absent
- J.
Myosin light-chain kinase participates in contraction
- K.
Possess(es) intercalated disks
Correct Answer(s)
B. T tubules are located at the A-I interface
G. Possess(es) triadsExplanation
The T tubules of skeletal muscle cells are positioned so that they form triads with the terminal cisternae of the sarcoplasmic reticulum at the interface of the A and I bands.Rate this question:
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- 2.
Cardiac muscle (SELECT 4 OPTIONS)
- A.
T tubules are located at the Z disk
- B.
T tubules are located at the A-I interface
- C.
T tubules are lined by external lamina
- D.
T tubules are absent
- E.
Oxytocin triggers contraction
- F.
Possess(es) dyads
- G.
Possess(es) triads
- H.
Possess caveolae
- I.
Troponin is absent
- J.
Myosin light-chain kinase participates in contraction
- K.
Possess(es) intercalated disks
Correct Answer(s)
A. T tubules are located at the Z disk
C. T tubules are lined by external lamina
F. Possess(es) dyads
K. Possess(es) intercalated disksExplanation
The T tubules of cardiac muscle cells are wider than those of skeletal muscle cells and are lined by external lamina (a basal lamina-like material). In contrast to skeletal muscle, the T tubules are located at the Z disk, where they often form dyads. Individual cardiac muscle cells are attached to one another by intercalated disks.Rate this question:
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- 3.
Smooth muscle (SELECT 5 OPTIONS)
- A.
T tubules are located at the Z disk
- B.
T tubules are located at the A-I interface
- C.
T tubules are lined by external lamina
- D.
T tubules are absent
- E.
Oxytocin triggers contraction
- F.
Possess(es) dyads
- G.
Possess(es) triads
- H.
Possess caveolae
- I.
Troponin is absent
- J.
Myosin light-chain kinase participates in contraction
- K.
Possess(es) intercalated disks
Correct Answer(s)
D. T tubules are absent
E. Oxytocin triggers contraction
H. Possess caveolae
I. Troponin is absent
J. Myosin light-chain kinase participates in contractionExplanation
Smooth muscle cells do not have T tubules. Contraction may be initiated by stretching, neural impulses, the intercellular passage of small molecules via gap junctions, or the action of hormones such as oxytocin. The process of contraction is not dependent on troponin, which is absent from the thin filament of smooth muscle. Instead, calcium ions controlled by sarcolemmal vesicles known as caveolae are released into the cytosol, where they bind with calmodulin. The calcium-calmodulin complex activates myosin light chain kinase, which participates in the contraction process.Rate this question:
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- 4.
Contraction in all types of muscle requires calcium ions. Which of the following muscle components can bind or sequester calcium ions?
- A.
Rough endoplasmic reticulum
- B.
Tropomyosin
- C.
Troponin
- D.
Active sites on actin
Correct Answer
C. TroponinExplanation
Binding of calcium ions to the TnC subunit of troponin leads to the uncovering of myosinbinding
sites on actin (thin filaments).Rate this question:
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- 5.
Each smooth muscle cell
- A.
Has triads associated with its contraction
- B.
Has dyads associated with its contraction
- C.
Possesses a single centrally located nucleus
- D.
Is characterized by the absence of sarcolemmal vesicles
Correct Answer
C. Possesses a single centrally located nucleusExplanation
Smooth muscle cells contain one centrally located nucleus.Rate this question:
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- 6.
Thick filaments are anchored to Z disks by
- A.
C protein
- B.
Nebulin
- C.
Titin
- D.
Myomesin
- E.
A-actinin
Correct Answer
C. TitinExplanation
Titin forms an elastic lattice that anchors thick filaments to Z disks.Rate this question:
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- 7.
The endomysium is a connective tissue investment that surrounds
- A.
Individual muscle fibers
- B.
Muscle fascicles
- C.
Individual myofibrils
- D.
An entire muscle
- E.
Small bundles of muscle cells
Correct Answer
A. Individual muscle fibersExplanation
The endomysium is a thin connective tissue layer, composed of reticular fibers and an external
lamina, that invests individual muscle fibers (cells). The epimysium surrounds the entire
muscle, and the perimysium surrounds bundles (fascicles) of muscle fibers.Rate this question:
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- 8.
Which of the following statements concerning triads in mammalian skeletal muscle is true?
- A.
They are located in the Z disk.
- B.
They consist of two terminal cisternae of the sarcoplasmic reticulum separated by a T tubule.
- C.
They can be observed with the light microscope.
- D.
They are characterized by a T tubule that sequesters calcium ions
- E.
They consist of two T tubules separated by a central terminal cisterna.
Correct Answer
B. They consist of two terminal cisternae of the sarcoplasmic reticulum separated by a T tubule.Explanation
A triad in skeletal muscle is composed of three components, a T tubule and two terminal cisternae of the sarcoplasmic reticulum (SR) that flank it. The SR, not the T tubules, sequesters calcium ions.Rate this question:
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- 9.
Which one of the following statements concerning cardiac muscle cells is true?
- A.
They are spindle shaped.
- B.
They require an external stimulus to undergo contraction
- C.
They are multinuclear cells.
- D.
They are joined together end-to-end by intercalated disks
- E.
They possess numerous caveolae.
Correct Answer
D. They are joined together end-to-end by intercalated disksExplanation
Cardiac muscle cells are joined together end-to-end by a unique junctional specialization
called the intercalated disk.Rate this question:
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- 10.
A 19-year-old male patient and his mother arrive in the emergency room, both suffering with nausea, vomiting, and visual disorders. The physician taking their history notes that they both had canned green beans that "tasted funny." Which of the following possibilities should the physician consider?
- A.
Duchenne muscular dystrophy
- B.
Amyotrophic lateral sclerosis
- C.
Botulism
- D.
Myasthenia gravis
- E.
Myocardial infarct
Correct Answer
C. BotulismExplanation
Botulism is the only possible consideration, especially after learning that they both had canned food. Duchenne muscular dystrophy is most common in young men but very rare in older women. It would be highly unlikely that both mother and son would show symptoms of amyatrophic lateral sclerosis or myasthenia gravis or have myocardial infarct at the same time.Rate this question:
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- 11.
Thick filaments are anchored at the M-Line by
- A.
C protein
- B.
Nebulin
- C.
Titin
- D.
Myomesin
- E.
A-actinin
Correct Answer
A. C proteinExplanation
C protein (clamp protein) anchors at the M-line.
Titin forms an elastic lattice that anchors thick filaments to Z disks.
Nebulin anchors to THIN filamentsRate this question:
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- 12.
The Perimysium is a connective tissue investment that surrounds
- A.
Individual muscle fibers
- B.
Muscle fascicles
- C.
Individual myofibrils
- D.
An entire muscle
- E.
Small bundles of muscle cells
Correct Answer
B. Muscle fasciclesExplanation
Perimysium surrounds Fasicles.
The endomysium is a thin connective tissue layer, composed of reticular fibers and an external lamina, that invests individual muscle fibers (cells).
The EPIMYSIUM surrounds the entire muscle.Rate this question:
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Current Version
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Mar 22, 2023Quiz Edited by
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Oct 20, 2011Quiz Created by
Chachelly
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