Deck 9: Skeletal Muscle Tissue

Question 1

The advantage of having many nuclei in a skeletal muscle fiber is the ability to

A)contract.
B)produce more ATP with little oxygen.
C)store extra DNA for metabolism.
D)produce large amounts of the muscle proteins needed for muscle contraction.
E)All of the answers are correct.

Answer 1

D

Question 2

Muscle fibers differ from "typical cells" in that muscle fibers

A)lack a plasma membrane.
B)have many nuclei.
C)are very small.
D)lack mitochondria.
E)All of the answers are correct.

Answer 2

B

Question 3

Which of the following statements is incorrect?

A)The contractions of skeletal muscles pull on tendons and move bones of the skeleton.
B)Skeletal muscles store nutrient reserves.
C)Skeletal muscles are responsible for the pumping action of the heart.
D)Skeletal muscles support the weight of some internal organs.
E)Skeletal muscle contractions help maintain body temperature.

Answer 3

Skeletal muscles are responsible for the pumping action of the heart.

Question 4

At each end of the muscle,the collagen fibers of the epimysium,and each perimysium and endomysium,come together to form a

A)tendon.
B)satellite cell.
C)ligament.
D)tenosynovium.
E)sheath.

Question 5

The region of the sarcomere that always contains only thin filaments is the

A)Z line.
B)M line.
C)H band.
D)A band.
E)I band.

Question 6

________ are stem cells located between the endomysium and sarcolemma that function in the repair of damaged muscle tissue.

A)Myosatellite cells
B)Myofilaments
C)Myofibrils
D)Multinucleate cells
E)Myoblasts

Question 7

Which of the following best describes the sarcoplasmic reticulum?

A)protein that accounts for elasticity of resting muscle
B)repeating unit of striated myofibrils
C)storage and release site for calcium ions
D)thin filaments are anchored here
E)largely made of myosin molecules

Question 8

The region of the sarcomere containing the thick and thin filaments is the

A)Z line.
B)M line.
C)H band.
D)A band.
E)I band.

Question 9

Skeletal muscle fibers are formed from embryonic cells called

A)sarcomeres.
B)myofibrils.
C)myoblasts.
D)fascicles.
E)myomeres.

Question 10

Individual muscle cells are surrounded by what connective tissue?

A)endomysium
B)perimysium
C)sarcolemma
D)sarcomere
E)myofibrils

Question 11

The bundle of collagen fibers at the end of a skeletal muscle that attaches the muscle to bone is called a(n)

A)fascicle.
B)tendon.
C)ligament.
D)epimysium.
E)myofibril.

Question 12

The delicate connective tissue that surrounds the skeletal muscle fibers and ties adjacent muscle fibers together is the

A)endomysium.
B)perimysium.
C)epimysium.
D)superficial fascia.
E)periosteum.

Question 13

The plasma membrane of skeletal muscle is called the

A)sarcolemma.
B)sarcomere.
C)sarcosome.
D)sarcoplasmic reticulum.
E)sarcoplasm.

Question 14

Which of the following is not a recognized function of skeletal muscle?

A)produce movement
B)maintain posture
C)maintain body temperature
D)guard body entrances and exits
E)controlled involuntarily

Question 15

The area in the center of the A band that contains no thin filaments is the

A)Z line.
B)M line.
C)H band.
D)I band.
E)zone of overlap.

Question 16

Each skeletal muscle fiber contains ________ myofibrils.

A)50 to 100
B)100 to 150
C)150 to 200
D)200 to 500
E)hundreds to thousands

Question 17

The repeating contractile unit of a skeletal muscle fiber is the

A)sarcolemma.
B)sarcomere.
C)sarcoplasmic reticulum.
D)myofibril.
E)myofilament.

Question 18

Muscle tissue,one of the four basic tissue groups,consists chiefly of cells that are highly specialized for

A)conduction.
B)contraction.
C)peristalsis.
D)cushioning.
E)None of the answers is correct.

Question 19

Nerves and blood vessels that service the muscle fibers are located in the connective tissues of the

A)endomysium.
B)perimysium.
C)sarcolemma.
D)sarcomere.
E)myofibrils.

Question 20

The dense layer of connective tissue that surrounds an entire skeletal muscle is the

A)tendon.
B)epimysium.
C)endomysium.
D)perimysium.
E)fascicle.

Question 21

Figure 9-1

-Identify the structure where ATP is produced.

A)6
B)7
C)1
D)3
E)2

Question 22

Which of the following best describes the term titin?

A)substance that accounts for elasticity of resting muscle
B)repeating unit of striated myofibrils
C)storage site for calcium ions
D)where thin filaments are anchored
E)largely made of myosin molecules

Question 23

Which statement about the microscopic anatomy of skeletal muscle fibers is not true?

A)Tubular extensions of the sarcolemma penetrate the fiber transversely.
B)Cross striations result from the lateral alignment of thick and thin filaments.
C)Each fiber has many nuclei.
D)Muscle fibers are continuous from tendon to tendon.
E)Multiple myofibrils link end-to-end along length of the muscle cell.

Question 24

At rest,active sites on the actin are blocked by

A)myosin molecules.
B)troponin molecules.
C)tropomyosin molecules.
D)calcium ions.
E)ATP molecules.

Question 25

Interactions between actin and myosin filaments of the sarcomere are responsible for

A)muscle fatigue.
B)the conduction of neural stimulation to the muscle fiber.
C)muscle contraction.
D)muscle relaxation.
E)the striped appearance of skeletal muscle.

Question 26

At rest,the tropomyosin molecule is held in place by

A)actin molecules.
B)myosin molecules.
C)troponin molecules.
D)ATP molecules.
E)calcium ions.

Question 27

The skeletal muscle complex known as the triad consists of

A)actin,myosin,and sarcomeres.
B)a transverse tubule and two terminal cisternae.
C)filaments,myofibrils,and muscle fibers.
D)A bands,H bands,and I bands.
E)a terminal cisterna and two transverse tubules.

Question 28

Which of the following best describes the term "Z line"?

A)protein that accounts for elasticity of resting muscle
B)repeating unit of striated myofibrils
C)storage site for calcium ions
D)where thin filaments are anchored
E)largely made of myosin molecules

Question 29

Figure 9-1

-Which of the following is not found in the structure labeled "3"?

A)actin
B)myosin
C)titin
D)tropomyosin
E)mitochondria

Question 30

Figure 9-1

-Where would calcium ions be predominately found?

A)1
B)2
C)4
D)8
E)9

Question 31

Figure 9-1

-Where is ATP is consumed?

A)1
B)2
C)3
D)7
E)8

Question 32

In a sarcomere,thick filaments are linked laterally by proteins of the

A)Z line.
B)M line.
C)H band.
D)A band.
E)I band.

Question 33

Figure 9-1

-Where are the myosin molecules located?

A)4
B)5
C)6
D)7
E)8

Question 34

The complex of a transverse tubule and two adjacent terminal cisternae is known as a(n)

A)free head.
B)zone of overlap.
C)M line.
D)triad.
E)sarcomere.

Question 35

Which of the following proteins is not found as a part of thin filaments?

A)actin
B)tropomyosin
C)troponin
D)nebulin
E)titin

Question 36

Physical evidence that supports the sliding filament theory of muscle contraction includes

A)constant distance between Z lines during contraction.
B)decreased width of the H band during contraction.
C)increased width of the I band during contraction.
D)decreased width of the A band during contraction.
E)the I band and H band distance is constant during contraction.

Question 37

Figure 9-1

-What is released from the structure labeled "9"?

A)sodium
B)acetylcholine
C)proteins
D)calcium ions
E)acetylcholinesterase

Question 38

Each thin filament consists of

A)two protein strands coiled helically around each other.
B)chains of myosin molecules.
C)six molecules in a rod-like structure.
D)a rod-shaped structure with "heads" projecting from each end.
E)a double strand of myosin molecules.

Question 39

Figure 9-1

-Identify the structures labeled "1."

A)mitochondria
B)glycogen
C)ATP
D)myofibril
E)synaptic vesicle

Question 40

Figure 9-1

-What physiological process occurs in the structure labeled "7"?

A)release of acetylcholine
B)conduction of the action potential toward the triad
C)acetylcholinesterase breakdown of acetylcholine
D)release of proteins into the muscle fiber
E)the sliding of actin and myosin filaments

Question 41

Which of the following statements is not true about action potentials?

A)They can travel long distances within cells.
B)They occur in neurons.
C)They end in repolarization.
D)They can be generated in less than 2 msec.
E)They can travel in two directions.

Question 42

If potassium channels were blocked,the ________ phase of the action potential would not occur normally.

A)repolarization
B)depolarization
C)refractory
D)threshold

Question 43

Na⁺ and K⁺ both use ________ to passively diffuse across the plasma membrane.

A)facilitated diffusion
B)exocytosis
C)voltage-gated channels
D)leak channels
E)carrier-mediated transport

Question 44

Since each myofibril is attached at either end of the muscle fiber,when sarcomeres shorten,the muscle fiber

A)lengthens.
B)shortens.
C)strengthens.
D)weakens.
E)There is insufficient information to determine the answer.

Question 45

The action potential is conducted into a skeletal muscle fiber by

A)motor end plates.
B)neuromuscular junctions.
C)transverse tubules.
D)triads.
E)sarcoplasmic reticulum.

Question 46

In response to action potentials arriving along the transverse tubules,the sarcoplasmic reticulum releases

A)acetylcholine.
B)sodium ions.
C)potassium ions.
D)calcium ions.
E)hydrogen ions.

Question 47

Synaptic vesicles containing neurotransmitters are released by ________ when the action potential arrives.

A)endocytosis
B)apoptosis
C)exocytosis
D)hydrolysis
E)sodium

Question 48

Receptors for acetylcholine are located on the

A)synaptic knob.
B)motor end plate.
C)sarcomere.
D)synaptic cleft.
E)transverse tubule.

Question 49

Neurons and ________ have electrically excitable membranes that propagate action potentials.

A)osteocytes
B)muscle cells
C)epithelial cells
D)proteins
E)dense connective tissue

Question 50

If the membrane potential of a neuron is -80 mV,it is

A)at resting potential.
B)at threshold.
C)depolarized.
D)repolarized.
E)hyperpolarized during the refractory period

Question 51

Cellular membrane potential is measured in

A)milliseconds.
B)micrometers.
C)Hertz.
D)millivolts.
E)amperes.

Question 52

The narrow space between the synaptic terminal and the muscle fiber is the

A)synaptic knob.
B)motor end plate.
C)motor unit.
D)synaptic cleft.
E)M line.

Question 53

Each skeletal muscle fiber is controlled by a motor neuron at a single

A)synaptic knob.
B)sarcomere.
C)neuromuscular junction.
D)synaptic cleft.
E)transverse tubule.

Question 54

The structural explanation of how a muscle fiber contracts is called the

A)myosin spiral theory.
B)thin filament theory.
C)sliding filament theory.
D)cross-bridge connection.
E)active site rule.

Question 55

Which of the following is an ion that is more concentrated inside the cell than outside?

A)sodium
B)chloride
C)hydrogen
D)calcium
E)potassium

Question 56

When a skeletal muscle fiber contracts,which of the following does not occur?

A)The H bands and I bands get smaller.
B)The zones of overlap get larger.
C)The Z lines get closer together.
D)The width of the A band remains constant.
E)Myosin and actin filaments decrease in length.

Question 57

Membrane potential is

A)a chemical signal that has not yet bound to a receptor.
B)a cell's capacity to respond to a chemical signal.
C)the electrical gradient of a cell.
D)the site of signal transfer between two cells.
E)the period when the membrane cannot respond to another stimulus.

Question 58

The Na⁺/K⁺ ion pump is responsible for

A)diffusing chloride across the plasma membrane.
B)transferring messages from enzyme-linked receptors to the cell nucleus.
C)maintaining the sodium/potassium concentration gradients constant.
D)initiating action potentials.
E)amplifying signals using ATP.

Question 59

Cross-bridges are portions of

A)actin molecules.
B)myosin molecules.
C)troponin molecules.
D)tropomyosin molecules.
E)calcium ions.

Question 60

During the ________ phase of action potential development,voltage-gated sodium channels are open.

A)repolarization
B)depolarization
C)refractory
D)threshold

Question 61

Communication between axons and muscle fibers occurs at specialized synapses called

A)junctional folds.
B)neuromuscular junctions.
C)motor end plates.
D)active sites.
E)Z lines.

Question 62

A muscle producing tension that peaks but falls to only intermediate stimulus rates is said to be in

A)incomplete tetanus.
B)complete tetanus.
C)treppe.
D)wave summation.
E)recruitment.

Question 63

Triggering of the muscle action potential occurs after

A)acetylcholine binds to chemically gated channels in the motor end plate membrane.
B)acetylcholinesterase binds to receptors on the end plate.
C)calcium ion binds to channels on the end plate.
D)the nerve action potential jumps across the neuromuscular junction.
E)Any of these actions can produce an action potential in the muscle cell.

Question 64

When calcium ion binds to troponin,

A)tropomyosin moves into the groove between the helical actin strands.
B)active sites on the myosin are exposed.
C)troponin shifts to expose the active sites on actin.
D)muscle relaxation occurs.
E)myosin shortens.

Question 65

Which statement about excitation-contraction coupling is incorrect?

A)Calcium ion is released from the transverse tubule.
B)Calcium ion is released from the sarcoplasmic reticulum.
C)Tropomyosin moves to expose myosin binding sites on actin.
D)Troponin binds calcium ion and signals tropomyosin to move.
E)Relaxation requires uptake of calcium ions by the sarcoplasmic reticulum.

Question 66

Which of the following become connected by myosin cross-bridges during muscle contraction?

A)thin filaments and thick filaments
B)thick filaments and titin filaments
C)Z disks and actin filaments
D)thick filaments and T tubules
E)thin filaments and T tubules

Question 67

How would the loss of acetylcholinesterase from the motor end plate affect skeletal muscle?

A)It would make the muscles less excitable.
B)It would produce muscle weakness.
C)It would cause spastic paralysis (muscles are contracted and unable to relax).
D)It would cause flaccid paralysis (muscles are relaxed and unable to contract).
E)It would have little effect on skeletal muscles.

Question 68

The cytoplasm of the neuromuscular synaptic terminal contains vesicles filled with molecules of the neurotransmitter

A)epinephrine.
B)norepinephrine.
C)acetylcholine.
D)antidiuretic hormone.
E)acetylcholinesterase.

Question 69

When acetylcholine binds to receptors at the motor end plate,the end plate membrane becomes

A)more permeable to sodium ions.
B)less permeable to sodium ions.
C)more permeable to calcium ions.
D)less permeable to potassium ions.
E)repolarized.

Question 70

Which of the following is greater?

A)the concentration of calcium ion in the sarcoplasm of a resting muscle
B)the concentration of calcium ion in the sarcoplasmic reticulum of a resting muscle

Question 71

Which of the following acts as an ATPase during the contraction cycle of muscle?

A)actin molecules
B)troponin molecules
C)tropomyosin molecules
D)the head portion of the myosin molecule
E)the tail portion of the myosin molecule

Question 72

Excitation-contraction coupling is the

A)sliding of thin filaments past thick filaments during muscle fiber contraction.
B)refractory period of an action potential.
C)threshold period of an action potential.
D)sequence of processes that links the action potential to contraction.
E)transfer of ACh into the synaptic cleft.

Question 73

The synchronous contraction of a single motor unit is known as a(n)

A)twitch.
B)asynchronous motor unit summation.
C)cross-bridge.
D)fasciculation.
E)muscle action potential.

Question 74

When a muscle is stimulated repeatedly at a high rate,eliminating a relaxation phase,the amount of tension gradually increases to a steady maximum tension.This is called

A)incomplete tetanus.
B)complete tetanus.
C)a twitch.
D)wave summation.
E)recruitment.

Question 75

Calcium ions are bound to troponin during which of the following steps.

A)latent period
B)contraction phase
C)recovery phase
D)the first 2 msec following stimulation
E)None of the answers is correct.

Question 76

The rapid rise and fall in force produced by a muscle fiber after a single action potential is a(n)

A)tetanus.
B)unfused tetanus.
C)twitch.
D)end plate potential.
E)muscle action potential.

Question 77

How would a drug that blocks acetylcholine receptors at the motor end plate affect skeletal muscle?

A)It would make the muscles more excitable.
B)It would produce uncontrolled muscle spasms.
C)It would cause spastic paralysis (muscles are contracted and unable to relax).
D)It would cause flaccid paralysis (muscles are relaxed and unable to contract).
E)It would have little effect on skeletal muscles.

Question 78

If a second stimulus arrives before the relaxation phase has ended,a second,more powerful contraction occurs.This is called

A)incomplete tetanus.
B)complete tetanus.
C)treppe.
D)wave summation.
E)recruitment.

Question 79

The most important factor in decreasing the intracellular concentration of calcium ion after contraction is

A)active transport of calcium across the sarcolemma.
B)active transport of calcium back into the sarcoplasmic reticulum.
C)active transport of calcium into the synaptic cleft.
D)diffusion of calcium out of the cell.
E)diffusion of calcium into the sarcoplasmic reticulum.

Question 80

Which process employs exocytosis?

A)facilitated diffusion
B)chemical synapse
C)depolarization
D)antagonist binding
E)cross-bridge formation