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1401- Anatomy > L5 - Muscle Tissue > Flashcards

L5 - Muscle Tissue Flashcards

1
Q
  1. Which of the following properties of muscle tissue allows it to return to its original shape after stretching?
    a) Excitability
    b) Contractility
    c) Extensibility
    d) Elasticity
A
  1. d) Elasticity
    Elasticity allows muscles to return to their original shape after stretching
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2
Q
  1. Which of the following muscle types is striated and under voluntary control?
    a) Cardiac muscle
    b) Skeletal muscle
    c) Smooth muscle
    d) Both cardiac and skeletal muscles
A
  1. b) Skeletal muscle
    Skeletal muscle is the only muscle type that is striated and under voluntary control.
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3
Q
  1. The contractile unit of a skeletal muscle fiber is the:
    a) Myofibril
    b) Sarcomere
    c) Sarcolemma
    d) Epimysium
A
  1. b) Sarcomere
    The sarcomere is the functional contractile unit of a skeletal muscle fiber.
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4
Q
  1. Which structure stores calcium ions in skeletal muscle cells?
    a) Sarcomere
    b) Sarcoplasmic reticulum
    c) Sarcolemma
    d) Myosin filaments
A
  1. b) Sarcoplasmic reticulum
    The sarcoplasmic reticulum stores calcium ions, which are released to initiate muscle contraction.
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4
Q
  1. Which connective tissue layer surrounds the entire smooth muscle?
    a) Endomysium
    b) Perimysium
    c) Epimysium
    d) Sarcoplasmic reticulum
A
  1. c) Epimysium
    The epimysium is the outermost layer of connective tissue that surrounds the entire muscle.
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4
Q
  1. The plasma membrane of a muscle cell is called the __________.
A
  1. Sarcolemma
    The plasma membrane of a muscle cell is called the sarcolemma.
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5
Q
  1. Cardiac muscle cells are incapable of regeneration, but they can hypertrophy.
    a) True
    b) False
A
  1. a) True
    Cardiac muscles cannot regenerate but can hypertrophy (enlarge in response to increased workload).
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5
Q
  1. Explain how skeletal muscle regenerates following damage.
A
  1. Skeletal muscle regenerates via satellite cells, which are quiescent cells that divide and fuse with existing muscle fibers to repair damage.
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5
Q
  1. _________ is the main regulatory protein in skeletal muscle responsible for binding calcium to initiate contraction.
A
  1. Troponin
    Troponin binds calcium in skeletal muscle to regulate contraction.
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6
Q
  1. Differentiate between the function of agonist and antagonist muscles during movement.
A
  1. The agonist is the prime mover that initiates movement, while the antagonist opposes the movement, helping to control or stop it.
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6
Q
  1. Smooth muscles are striated and under voluntary control.
    a) True
    b) False
A
  1. b) False
    Smooth muscles are non-striated and involuntary.
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7
Q

Select all that apply - 12. Which of the following are part of the sarcomere?
a) Z line
b) I band
c) H zone
d) A band
e) Myosin filament
f) Actin filament

A
  1. a, b, c, d, e, f
    The sarcomere contains Z lines, I bands, H zones, A bands, and both myosin and actin filaments.
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8
Q

Select all that apply - 13. Which of the following is involved in the neuromuscular junction?
a) Synaptic cleft
b) Junctional folds
c) Presynaptic vesicles
d) Mitochondria
e) Troponin

A
  1. a, b, c, d
    The synaptic cleft, junctional folds, presynaptic vesicles, and mitochondria are involved in the neuromuscular junction.
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9
Q
  1. A patient presents with muscle weakness and fatigue. Testing reveals antibodies that impair neuromuscular transmission at the postsynaptic membrane. What condition does this patient likely have? Describe the cause and how it affects muscle function.
A
  1. The patient likely has Myasthenia Gravis, an autoimmune disorder that disrupts communication between nerves and muscles due to antibodies attacking the postsynaptic membrane, leading to muscle weakness and fatigue.
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10
Q

Fill-in-the-Blank:
16. The thin filaments of the sarcomere are primarily composed of the protein __________, while thick filaments are composed of __________.

A
  1. Actin, myosin
    Thin filaments are primarily composed of actin, while thick filaments are made of myosin.
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11
Q
  1. Which muscle type has the greatest ability to regenerate following damage?
    a) Skeletal muscle
    b) Smooth muscle
    c) Cardiac muscle
    d) All muscle types regenerate equally well
A
  1. b) Smooth muscle
    Smooth muscle has the greatest ability to regenerate because the muscle cells themselves can divide, unlike skeletal and cardiac muscles.
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12
Q

Select All That Apply:
18. Which of the following diseases affect the neuromuscular junction or muscle structure?
a) Myasthenia Gravis
b) Duchenne Muscular Dystrophy
c) Multiple Sclerosis
d) Muscular Dystrophy
e) Parkinson’s disease

A
  1. a, b, d
    Myasthenia Gravis affects the NMJ, Duchenne Muscular Dystrophy affects the dystrophin gene, and muscular dystrophy affects muscle structure. Multiple sclerosis and Parkinson’s are not primarily muscle disorders.
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12
Q
  1. Skeletal muscles can undergo both hypertrophy and regeneration via satellite cells, while cardiac muscles are only capable of hypertrophy.
    a) True
    b) False
A

a) True
Skeletal muscles regenerate using satellite cells, while cardiac muscle cannot regenerate and relies only on hypertrophy.

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13
Q
  1. Which of the following best describes the H zone in a sarcomere?
    a) The region where actin and myosin overlap
    b) The area containing only myosin filaments
    c) The part that contains only actin filaments
    d) The Z line within the sarcomere
A
  1. b) The area containing only myosin filaments
    The H zone is located in the center of the A band and contains only thick (myosin) filaments.
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13
Q

Clinical Scenario:
19. A 40-year-old male presents with progressive muscle weakness in his limbs. Genetic testing reveals a mutation in the dystrophin gene. What condition does this patient likely have, and how does this mutation affect muscle function?

A
  1. The patient likely has Duchenne Muscular Dystrophy (DMD), a genetic disorder caused by a mutation in the dystrophin gene. This mutation leads to progressive muscle degeneration and weakness because dystrophin is essential for stabilizing the muscle cell membrane during contraction. Without it, muscles are more prone to damage and degeneration.
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14
Q
  1. Which muscle type has intercalated discs, allowing for synchronized contractions?
    a) Skeletal muscle
    b) Smooth muscle
    c) Cardiac muscle
    d) All of the above
A
  1. c) Cardiac muscle
    Intercalated discs are unique to cardiac muscle, allowing for coordinated contractions.
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15
Q

Fill-in-the-Blank:
22. The functional unit of a myofibril, responsible for muscle contraction, is called a __________.

A
  1. Sarcomere
    The sarcomere is the smallest contractile unit of a muscle fiber
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15
Q

Fill-in-the-Blank:
23. The __________ band contains only thin filaments, while the __________ band contains both thick and thin filaments.

A
  1. I, A
    The I band contains only thin filaments (actin), while the A band contains both thick and thin filaments.
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16
Q
  1. The H zone becomes smaller during muscle contraction as actin filaments slide toward the M line.
    a) True
    b) False
A
  1. a) True
    The H zone shortens as actin filaments slide towards the center during muscle contraction
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17
Q
  1. During muscle contraction, the length of the A band remains constant, but the I band shortens.
    a) True
    b) False
A
  1. a) True
    The A band stays the same length during contraction, while the I band shortens as actin filaments slide inward.
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18
Q
  1. Explain the structural difference between the I band, A band, and H zone in a sarcomere.
A
  1. The I band contains only actin (thin filaments), the A band contains both actin and myosin, and the H zone contains only myosin (thick filaments) and shortens during contraction.
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19
Q
  1. What role do troponin and tropomyosin play in the regulation of muscle contraction?
A
  1. Troponin binds calcium, causing tropomyosin to move away from actin’s binding sites, allowing myosin to interact with actin and initiate contraction.
20
Q

Select All That Apply:
28. Which structures can be found in a sarcomere?
a) M line
b) H zone
c) I band
d) Z line
e) Triad
f) A band

A
  1. a, b, c, d, f
    The sarcomere includes the M line, H zone, I band, Z line, and A band, but not the triad (which is part of the sarcoplasmic reticulum system).
21
Q

Select all that apply
29. Which of the following are characteristics of cardiac muscle?
a) Striated appearance
b) Voluntary control
c) Branched fibers
d) Presence of intercalated discs
e) Multi-nucleated

A
  1. a, c, d
    Cardiac muscle is striated, has branched fibers, and contains intercalated discs. It is involuntary and typically has one nucleus per cell.
22
Q

Clinical Scenario:
30. A 23-year-old athlete notices a decrease in the force of muscle contractions after repetitive activity. After testing, it is determined that calcium is not being released properly from the sarcoplasmic reticulum. Which structure in the muscle fiber might be defective, and how does this affect muscle contraction?

A
  1. The defective structure is likely the sarcoplasmic reticulum. Without proper calcium release, troponin cannot bind to calcium, preventing the muscle contraction cycle from occurring efficiently.
22
Q
  1. The neuromuscular junction (NMJ) is the site where:
    a) Calcium is stored in muscle fibers
    b) A nerve impulse triggers the release of acetylcholine
    c) Muscle fibers regenerate after injury
    d) Actin and myosin interact to cause contraction
A
  1. b) A nerve impulse triggers the release of acetylcholine
    The NMJ is where a motor neuron releases acetylcholine to initiate muscle contraction.
23
Q
  1. Acetylcholine is released at the __________, where it binds to receptors on the __________ to trigger an action potential in the muscle fiber.
A
  1. Neuromuscular junction, sarcolemma
    Acetylcholine binds to receptors on the sarcolemma to initiate a muscle action potential
24
Q
  1. During muscle contraction, the __________ shortens while the __________ remains the same length.
A
  1. Sarcomere, A band
    The sarcomere shortens during contraction, but the A band remains the same length.
25
Q
  1. The M line in a sarcomere represents the center of the H zone, where myosin filaments are anchored.
    a) True
    b) False
A
  1. a) True
    The M line is the central region of the H zone and anchors the myosin filaments.
26
Q
  1. The sliding filament mechanism describes how actin and myosin filaments shorten during muscle contraction.
    a) True
    b) False
A
  1. b) False
    The sliding filament mechanism describes how actin filaments slide over myosin filaments; the filaments themselves do not shorten.
26
Q
  1. What is the role of the sarcoplasmic reticulum in muscle contraction, and how does calcium regulate this process?
A
  1. The sarcoplasmic reticulum stores calcium, and when stimulated, it releases calcium into the sarcoplasm. Calcium binds to troponin, causing tropomyosin to move and expose myosin-binding sites on actin, initiating contraction.
26
Q

Select all that apply - 39. Which of the following are involved in the process of muscle contraction?
a) Myosin heads
b) Actin filaments
c) Acetylcholine
d) Sarcoplasmic reticulum
e) ATP

A
  1. a, b, c, d, e
    All of these are involved in muscle contraction. Myosin heads bind to actin, acetylcholine initiates the process, the sarcoplasmic reticulum releases calcium, and ATP provides the energy.
27
Q
  1. A 65-year-old man is diagnosed with Myasthenia Gravis after experiencing muscle fatigue and weakness, especially in his eyelids and face. Which part of the neuromuscular junction is primarily affected in this disorder, and how does this impair muscle contraction?
A
  1. In Myasthenia Gravis, acetylcholine receptors on the sarcolemma are affected, leading to impaired communication between nerves and muscles, causing weakness and fatigue.
28
Q
  1. Which structure forms the boundaries of a sarcomere?
    a) M line
    b) A band
    c) Z line
    d) H zone
A
  1. c) Z line
    The Z line marks the boundary between adjacent sarcomeres and is where actin filaments are anchored.
29
Q
  1. Which of the following muscle types is under involuntary control and does not exhibit striations?
    a) Skeletal muscle
    b) Cardiac muscle
    c) Smooth muscle
    d) All of the above
A
  1. c) Smooth muscle
    Smooth muscle is involuntary and lacks the striations seen in skeletal and cardiac muscle.
30
Q
  1. The __________ is the point where a neuron and a muscle fiber meet, and neurotransmitters are released to trigger muscle contraction.
A
  1. Neuromuscular junction
    The neuromuscular junction is where the nerve and muscle fiber communicate, triggering contraction.
31
Q
  1. Myosin filaments are anchored to the Z line, while actin filaments are anchored to the M line.
    a) True
    b) False
A
  1. b) False
    Actin filaments are anchored to the Z line, while myosin filaments are anchored to the M line.
31
Q
  1. Muscle fibers contain numerous cylindrical bundles called __________, which are made up of repeating units called __________.
A
  1. Myofibrils, sarcomeres
    Myofibrils are cylindrical structures within muscle fibers made up of repeating sarcomeres.
32
Q
  1. During contraction, the I band shortens while the A band stays the same.
    a) True
    b) False
A
  1. a) True
    During contraction, the I band (which contains only actin) shortens, while the A band (which contains both actin and myosin) remains the same.
33
Q
  1. Describe the role of acetylcholinesterase in the neuromuscular junction and its importance in regulating muscle contraction.
A
  1. Acetylcholinesterase breaks down acetylcholine in the synaptic cleft, stopping its action and allowing muscle relaxation. Without this enzyme, continuous stimulation could occur, leading to sustained contraction (tetany).
33
Q
  1. Explain how the sliding filament model describes the process of muscle contraction.
A
  1. The sliding filament model describes how actin filaments slide past myosin filaments during contraction. This movement shortens the sarcomere and results in muscle contraction without changing the length of the filaments themselves.
34
Q

Select all that apply
51. Which structural components are present in a skeletal muscle fiber?
a) Sarcoplasmic reticulum
b) Myofibrils
c) Sarcolemma
d) Perimysium
e) Endomysium

A
  1. a, b, c, e
    The sarcoplasmic reticulum stores calcium, myofibrils contain sarcomeres, the sarcolemma is the muscle fiber membrane, and the endomysium is the connective tissue that surrounds each muscle fiber.
35
Q

Select all that apply
50. Which of the following are regulatory proteins involved in muscle contraction?
a) Troponin
b) Tropomyosin
c) Myosin
d) Actin
e) Calmodulin

A
  1. a, b
    Troponin and tropomyosin are the primary regulatory proteins in muscle contraction. They regulate the interaction of actin and myosin. Myosin and actin are structural proteins, and calmodulin is more relevant in smooth muscle contraction.
36
Q
  1. A 12-year-old boy is brought to the clinic due to progressive muscle weakness and difficulty walking. His parents report that he struggles to get up from a seated position and has enlarged calves. Genetic testing confirms a diagnosis of Duchenne Muscular Dystrophy (DMD). Explain how the absence of dystrophin in this disorder leads to muscle weakness.
A
  1. In Duchenne Muscular Dystrophy, the absence of dystrophin, a protein that helps anchor the muscle cell membrane to the cytoskeleton, causes muscle cells to be more prone to damage. Over time, this leads to muscle degeneration and progressive weakness.
37
Q
  1. Which part of the neuromuscular junction contains the neurotransmitter acetylcholine?
    a) Synaptic cleft
    b) Synaptic vesicles in the presynaptic neuron
    c) Junctional folds
    d) Sarcoplasmic reticulum
A
  1. b) Synaptic vesicles in the presynaptic neuron
    Acetylcholine is stored in synaptic vesicles located in the presynaptic neuron, ready to be released into the synaptic cleft.
37
Q
  1. At the neuromuscular junction, acetylcholine is released into the __________ and binds to receptors on the __________.
A
  1. Synaptic cleft, sarcolemma

Acetylcholine is released into the synaptic cleft and binds to receptors on the sarcolemma of the muscle fiber.

38
Q
  1. Which of the following structures makes up the triad in skeletal muscle?
    a) Two T-tubules and one sarcoplasmic reticulum
    b) Two terminal cisternae and one T-tubule
    c) Two sarcomeres and one mitochondrion
    d) Two myofibrils and one nucleus
A
  1. b) Two terminal cisternae and one T-tubule
    The triad in skeletal muscle consists of two terminal cisternae of the sarcoplasmic reticulum and one T-tubule, allowing for rapid calcium release.
39
Q
  1. In smooth muscle, which of the following is responsible for initiating contraction by activating myosin light chain kinase?
    a) Troponin
    b) Calmodulin
    c) Tropomyosin
    d) Myosin
A
  1. b) Calmodulin
    In smooth muscle, calmodulin binds calcium and activates myosin light chain kinase to initiate contraction.
40
Q
  1. Satellite cells are responsible for the regeneration of cardiac muscle following injury.
    a) True
    b) False
A
  1. b) False
    Cardiac muscle does not regenerate via satellite cells, unlike skeletal muscle. Cardiac muscle lacks a significant regenerative capacity.
40
Q
  1. Smooth muscle cells have sarcomeres similar to skeletal muscle cells.
    a) True
    b) False
A
  1. b) False
    Smooth muscle cells do not have sarcomeres; their filaments are arranged in a different manner, giving them a non-striated appearance.
41
Q
  1. Describe the role of calcium in muscle contraction, explaining how it is stored and released in skeletal muscle.
A
  1. Calcium is stored in the sarcoplasmic reticulum and released into the sarcoplasm upon stimulation by an action potential. Calcium binds to troponin, initiating muscle contraction by exposing the active sites on actin. After contraction, calcium is pumped back into the sarcoplasmic reticulum, allowing relaxation.
41
Q

Select all that apply
63. Which processes occur during skeletal muscle hypertrophy?
a) Increase in the number of muscle fibers
b) Increase in the size of existing muscle fibers
c) Addition of myofilaments to existing myofibrils
d) Increase in the number of mitochondria
e) Division of existing muscle fibers

A
  1. b, c, d
    Hypertrophy involves an increase in the size of muscle fibers, the addition of myofilaments, and an increase in the number of mitochondria. Muscle fibers do not divide in hypertrophy.
41
Q
  1. The enzyme that breaks down ATP to provide energy for the power stroke of myosin is called __________.
A
  1. ATPase
    ATPase is the enzyme that breaks down ATP during the muscle contraction cycle.
41
Q
  1. During prolonged aerobic exercise, muscles primarily use __________ as their energy source.
A
  1. Fatty acids
    During prolonged aerobic exercise, muscles rely on fatty acids for energy.
41
Q
  1. Which of the following is a direct energy source for muscle contraction?
    a) Glucose
    b) ATP
    c) Lactic acid
    d) Creatine
A
  1. b) ATP
    ATP is the immediate source of energy for muscle contraction.
41
Q
  1. A 45-year-old patient presents with muscle stiffness and weakness. Testing reveals that calcium is not being adequately removed from the sarcoplasm after muscle contraction. Which protein or structure could be malfunctioning, and how does this affect muscle relaxation?
A
  1. The malfunctioning structure is likely the sarcoplasmic reticulum, specifically the calcium pumps (SERCA). If calcium is not removed from the sarcoplasm after contraction, muscle relaxation cannot occur properly, leading to stiffness and prolonged contraction.
42
Q
  1. ATP is only required during muscle contraction and not during muscle relaxation.
    a) True
    b) False
A
  1. b) False
    ATP is required both for contraction (for the power stroke) and for relaxation (to pump calcium back into the sarcoplasmic reticulum).
42
Q
  1. Muscle atrophy occurs when muscles decrease in size due to inactivity or disease.
    a) True
    b) False
A
  1. a) True
    Muscle atrophy is the loss of muscle mass, typically due to disuse, aging, or disease.
43
Q
  1. Describe the process of muscle fatigue and identify two factors that contribute to it.
A
  1. Muscle fatigue occurs when muscles can no longer generate force due to the depletion of energy sources like ATP and glycogen, as well as the accumulation of metabolic byproducts like lactic acid, which interfere with muscle function.
43
Q

Select all that apply - 73. Which of the following contribute to muscle fatigue during intense exercise?
a) Depletion of ATP
b) Lactic acid buildup
c) Accumulation of calcium in the sarcoplasmic reticulum
d) Lack of oxygen
e) Increased acetylcholine release

A
  1. a, b, d
    ATP depletion, lactic acid buildup, and lack of oxygen contribute to muscle fatigue. Calcium accumulation and increased acetylcholine release do not cause fatigue.

1401- Anatomy (9 decks)

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