Human Anatomy Physiology 1st Edition By Erin C. Amerman – Test Bank

Human Anatomy Physiology 1st Edition By Erin C. Amerman – Test Bank

Human Anatomy & Physiology, Global Edition (Amerman)
Chapter 10 Muscle Tissue and Physiology

1) What is the basic function of all muscle tissue?
A) generate muscle tension
B) produce voluntary contractions
C) regulate body temperature
D) stabilize joints
Answer: A
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.1.1

2) What do skeletal muscle tissue and cardiac muscle tissue share in common?
A) Both skeletal and cardiac muscle tissues are voluntary.
B) Both skeletal and cardiac muscle tissues are striated.
C) Both skeletal and cardiac muscle tissues possess intercalated discs.
D) Both skeletal and cardiac muscle tissues perform peristalsis.
Answer: B
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.1.3

3) What characteristic is NOT descriptive of cardiac muscle tissue?
A) intercalated discs
B) striations
C) voluntary muscle contractions
D) located in the heart
Answer: C
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.1.3

4) The degree to which a muscle cell can stretch depends on its:
A) excitability.
B) contractility.
C) extensibility.
D) conductivity.
Answer: C
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.1.2

5) The plasma membrane of a muscle cell is known as the:
A) myofibril.
B) sarcoplasmic reticulum.
C) sarcolemma.
D) sarcomere.
Answer: C
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.1.2
6) The storage and release of calcium ions is the key function of the:
A) sarcolemma.
B) sarcoplasm.
C) mitochondrion.
D) sarcoplasmic reticulum.
Answer: D
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.1

7) Deep inward extensions of the sarcolemma form a tunnel-like network inside the muscle cell known as:
A) the sarcoplasmic reticulum.
B) myofibrils.
C) myofilaments.
D) transverse tubules (T-tubules).
Answer: D
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.1

8) A triad consists of:
A) a transverse tubule (T-tubule) and two terminal cisternae.
B) a fascicle of skeletal muscle cells and its surrounding perimysium.
C) actin filaments, troponin, and tropomyosin.
D) myosin filaments, myosin heads, and myosin tails.
Answer: A
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.1

9) Which protein does NOT belong in a thin filament?
A) actin
B) troponin
C) tropomyosin
D) myosin
Answer: D
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.3

10) A group of skeletal muscle fibers together with the surrounding perimysium form a(n):
A) ligament.
B) endomysium.
C) fascicle.
D) myofibril.
Answer: C
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.1

11) Which of the following wraps and surrounds an individual skeletal muscle fiber?
A) endomysium
B) sarcoplasmic reticulum
C) perimysium
D) epimysium
Answer: A
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.1

12) What anchors thin and elastic filaments in place within the myofibril?
A) M line
B) Z disc
C) A band
D) I band
Answer: B
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.4

13) The central region of the A band that lacks thin filaments is the:
A) I band.
B) Z disc.
C) H zone.
D) sarcomere.
Answer: C
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.4

14) What is the functional contractile unit of the myofibril?
A) sarcolemma
B) A band
C) I band
D) sarcomere
Answer: D
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.4

15) Which of the following statements is the most accurate description of the sliding filament mechanism?
A) Z discs slide over the thick and thin filaments
B) both thick and thin filaments shorten
C) thick filaments shorten while thin filaments remain unchanged
D) thin filaments slide past thick filaments towards the M line.
Answer: D
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.2.5

16) What part of the myofibril shortens to produce contractions of the muscle fiber?
A) sarcomere
B) myosin filaments
C) A band
D) elastic filaments
Answer: A
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.5

17) When a skeletal muscle fiber contracts:
A) the H zone and I bands narrow.
B) the A bands shorten while the I bands lengthen.
C) Z discs move farther apart while the A bands shorten.
D) the H zone narrows while the I bands widen.
Answer: A
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.2.5

18) A muscle cell experiencing resting membrane potential is:
A) experiencing depolarization.
B) more negatively charged on its exterior than in its interior.
C) propagating an action potential.
D) polarized.
Answer: D
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.3.2

19) Where should most of the potassium ions be located when a muscle cell is at rest?
A) cytosol of the muscle cell
B) extracellular fluid
C) sarcoplasmic reticulum
D) tranverse tubules (T-tubules)
Answer: A
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.3.1

20) The Na+/K+ pump helps a muscle cell maintain a state of:
A) resting membrane potential.
B) action potential.
C) propagation.
D) depolarization.
Answer: A
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.3.3

21) Which of the following promotes the depolarization stage?
A) hydrolysis of ATP
B) opening of voltage-gated sodium ion channels and sodium ions enter the cell
C) closure of voltage-gated sodium ion channels
D) opening of voltage-gated potassium ion channels and potassium ions exit the cell
Answer: B
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.3.4

22) What value best represents resting membrane potential of skeletal muscle cells?
A) +15 mV
B) +35 mV
C) 0 mV
D) -85 mV
Answer: D
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.3.2

23) The synapse of a motor neuron with a muscle fiber is known as the:
A) neuromuscular junction.
B) motor end plate.
C) synaptic cleft.
D) synaptic bulb.
Answer: A
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.4.1

24) Where are receptors for acetylcholine located?
A) axon terminal
B) motor end plate
C) triad
D) sarcomere
Answer: B
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.4.1

25) Place the following events of excitation in the correct order.
1) ion channels on the sarcolemma open and sodium ions enter the muscle fiber
2) the entry of sodium ions into the muscle fiber depolarizes the sarcolemma locally
3) acetylcholine is released from vesicles in the motor neuron into the synaptic cleft
4) an action potential arrives at the axon terminal of a motor neuron
5) acetylcholine binds to ligand-gated sodium ion channels in the motor end plate
A) 2, 4, 3, 5, 1
B) 4, 3, 5, 1, 2
C) 3, 4, 5, 1, 2
D) 4, 5, 3, 2, 1
Answer: B
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.4.2
26) When an action potential arrives in an axon terminal, synaptic vesicles containing acetylcholine are released by:
A) exocytosis.
B) osmosis.
C) endocytosis.
D) facilitated diffusion.
Answer: A
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.4.2

27) What does the depolarization of the transverse tubules (T-tubules) promote?
A) binding of acetylcholine to ligand-gated sodium ion channels
B) release of calcium from the sarcoplasmic reticulum
C) release of acetylcholine from vesicles in the motor neuron into the synaptic cleft
D) entry of sodium ions into the muscle fiber through voltage-gated sodium ion channels
Answer: B
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.4.3

28) What is required for excitation-contraction coupling?
A) calcium ions and ATP
B) calcium ions only
C) ATP only
D) neither calcium ions nor ATP
Answer: A
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.4.3

29) During excitation-contraction coupling, calcium ion concentration is highest in the:
A) sarcoplasmic reticulum.
B) cytosol of the muscle fiber.
C) sarcolemma.
D) terminal cisterna.
Answer: B
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.4.3

30) The binding of a myosin head to an actin molecule is termed a:
A) power stroke.
B) triad.
C) crossbridge.
D) synaptic cleft.
Answer: C
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.4.4
31) During muscle contraction, myosin crossbridges bind to active sites on:
A) tropomyosin.
B) troponin.
C) actin.
D) T-tubules.
Answer: C
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.4.4

32) What is accomplished by the power stroke?
A) The power stroke allows the myosin heads to bind to actin.
B) The power stroke cocks the myosin head into its high-energy position.
C) The power stroke causes the myosin and actin filaments to shorten and contract.
D) The power stroke results in myosin heads pulling actin toward the center of the sarcomere.
Answer: D
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.4.4

33) What happens when troponin and tropomyosin block the active sites of actin?
A) The muscle produces a weak contraction.
B) The muscle relaxes.
C) The muscle contraction increases tension.
D) The muscle contraction reaches peak tension.
Answer: B
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.4.5

34) The main immediate source of ATP (lasting about 10 seconds) as muscle contractions begin comes from:
A) glucose.
B) glycogen.
C) creatine phosphate.
D) fat.
Answer: C
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.5.1

35) What is a necessary reactant for glycolytic, or anaerobic, catabolism to proceed?
A) glucose
B) oxygen
C) creatine phosphate
D) myoglobin
Answer: A
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.5.2
36) A pathway of ATP production that results in the formation of lactic acid is:
A) glycolytic catabolism.
B) anabolism.
C) oxidative catabolism.
D) aerobic catabolism.
Answer: A
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.5.2

37) What are possible products of glycolytic, or anaerobic, catabolism?
A) glucose only
B) oxygen only
C) creatine phosphate only
D) ATP, pyruvate, and lactic acid
Answer: D
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.5.2

38) Which statement best describes the function of myoglobin?
A) Myoglobin hydrolyzes ATP.
B) Myoglobin is a source of ATP for muscles.
C) Myoglobin catabolizes glycogen.
D) Myoglobin stores oxygen in muscle cells.
Answer: D
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.5.2

39) Through which ATP-generating mechanism can long-lasting muscle contractions be sustained?
A) glycolysis
B) anaerobic catabolism
C) creatine phosphate reaction
D) oxidative catabolism
Answer: D
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.5.3

40) Between the start of the latent period and the start of the contraction period, there is a time interval during which the muscle cannot respond to another stimulus. This brief period is known as the:
A) refractory period.
B) relaxation period.
C) tension period.
D) action potential.
Answer: A
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.6.1
41) Latrotoxin, produced by the poisonous black widow spider, increases the release of acetylcholine. How do muscle cells respond?
A) Muscle cells will become paralyzed when excess acetylcholine exists.
B) Muscle cells will twitch irregularly when excess acetylcholine exists.
C) Muscle cells will experience a longer latent period when excess acetylcholine exists.
D) Muscle cells will experience fused or complete tetanus when excess acetylcholine exists.
Answer: D
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.6.2

42) Clostridium botulinum is a bacterium that produces botulinum toxin that inhibits the release of acetylcholine. Which description best fits how muscle cells will respond to a lack of acetylcholine?
A) Muscle cells will experienced fused or complete tetanus when there is a lack of acetylcholine.
B) Muscle cells will produce greater tension when there is a lack of acetylcholine.
C) Muscle cells will produce sustained contractions without relaxation when there is a lack of acetylcholine.
D) Muscle cells will become paralyzed when there is a lack of acetylcholine.
Answer: D
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.6.2

43) When muscle fibers are stimulated so frequently they do not have an opportunity to relax, they are experiencing:
A) wave summation.
B) unfused or incomplete tetanus.
C) fused or complete tetanus.
D) twitch.
Answer: C
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.6.2

44) Type I fibers lack:
A) myoglobin.
B) mitochondria.
C) a blood supply.
D) speed.
Answer: D
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.6.3

45) The fastest muscle contraction would be produced by a:
A) type I fiber.
B) type IIx fiber.
C) type IIb fiber.
D) type IIc fiber.
Answer: C
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.6.3
46) Which fiber type helps Frances stand for hours in her job as a nurse?
A) type I fiber
B) type IIa fiber
C) type IIb fiber
D) type IIc fiber
Answer: A
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.6.3

47) A single motor neuron together with all the skeletal muscle fibers it innervates is called a:
A) motor end plate.
B) motor unit.
C) synaptic cleft.
D) neuromuscular junction.
Answer: B
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.7.1

48) The increase in muscle tension that is produced by increasing the number of active motor units is called:
A) recruitment.
B) isotonic contraction.
C) muscle tone.
D) wave summation.
Answer: A
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.7.1

49) Jorge tried to pick up his sofa but discover that it is much heavier than he expected. What must occur in the muscle to increase tension so he can pick up this heavy piece of furniture?
A) tetanic spasm
B) recruitment of additional motor units
C) pliometric contraction
D) isotonic eccentric contractions
Answer: B
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.6.1

50) The type of contraction in which length of the muscle fibers do not change is called:
A) isometric.
B) isotonic concentric.
C) isotonic eccentric.
D) tetany.
Answer: A
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.7.3
51) What type of contraction requires the greatest amount of tension?
A) isotonic concentric contraction
B) isotonic eccentric contraction
C) isometric contraction
D) miometric contraction
Answer: B
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.7.3

52) In response to physical inactivity, we expect to see muscles:
A) hypertrophy.
B) increase the diameter of the muscle fiber.
C) increase numbers of myofibrils.
D) atrophy.
Answer: D
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.8.1

53) Larry’s muscles weakened while he played tennis for hours on a hot summer afternoon. This inability to maintain intensity is defined as:
A) hypotonia.
B) muscle fatigue.
C) atrophy.
D) hypertonia.
Answer: B
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.8.2

54) During the recovery period after exercise, we breathe deeper and faster. This increased rate of respiration is known as:
A) muscle fatigue.
B) lactic acid buildup.
C) excess postexercise oxygen consumption (EPOC).
D) oxidative catabolism.
Answer: C
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.8.3

55) Smooth muscle and skeletal muscle both possess:
A) troponin.
B) myosin and actin filaments.
C) motor end plates.
D) transverse tubules (T-tubules).
Answer: B
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.9.1
56) What do skeletal muscle contractions share in common with smooth muscle contractions?
A) Both types of contractions consume very little ATP.
B) Both types of contractions generate little force or a weak force.
C) Both types of contractions do not require calcium ions for a contraction to occur.
D) Both types of contractions result from thick and thin filaments sliding past one another.
Answer: D
Bloom’s Taxonomy: 3) Analysis
Learning Outcome: 10.9.2

57) Provide two characteristics that distinguish skeletal muscle tissue from smooth muscle tissue.
Answer: 1) Smooth muscle tissue lacks striations that are visible in skeletal muscle tissue. 2) Smooth muscle cells are spindle-shaped with a single, centrally located oval nucleus while skeletal muscle cells are long and multinucleated.
Bloom’s Taxonomy: 3) Application
Learning Outcome: 10.1.3

58) Define excitability.
Answer: Excitability is the ability of a muscle cell to respond to a stimulus.
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.1.2

59) What are the inward extensions of the sarcolemma into the muscle cell called? What function do these extensions serve?
Answer: Inward extensions of the sarcolemma are known as transverse tubules (T-tubules). During excitation-contraction coupling, the action potential is carried down the T-tubules into the depths of the muscle fiber to stimulate the release of calcium ions from the terminal cisternae.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.2.1, 10.4.3

60) Describe the roles of contractile and regulatory proteins in the myofibril.
Answer: Contractile proteins produce tension while regulatory proteins control when the muscle can contract.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.2.2

61) What is the function of the sarcoplasmic reticulum?
Answer: The sarcoplasmic reticulum (SR) stores and releases calcium ions.
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.1

62) List and describe the types of contractile and regulatory proteins found in a thin filament.
Answer: A thin filament is composed of actin, tropomyosin, and troponin. Actin is a contractile protein. Actin has an area known as an active site that can bind a myosin head. Strings of actin molecules form the largest part of the thin filament. Tropomyosin is a regulatory protein that spirals around the actin strands and covers the active sites. Troponin is a second regulatory protein that holds tropomyosin in place and binds a calcium ion.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.2.4, 10.4.4
63) Describe the bands that create the light and dark areas of skeletal muscle fibers known as striations.
Answer: I bands and A bands create the light and dark areas known as striations on a skeletal muscle fiber. I bands, or light bands, contain only thin filaments. These bands are lighter because they allow more light to pass through. A bands, or dark bands, contain thick filaments. The thick filaments block more light than the thin filaments.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.2.4

64) Explain how a sarcomere is affected when thin filaments slide past thick filaments during muscle contraction.
Answer: As thin filaments slide past thick filaments during the sliding filament mechanism of muscle contraction, the sarcomere becomes shorter with each contraction. The action of the sliding filaments draws the Z discs closer together and causes the sarcomere as a whole to shorten as the filaments overlap.
Bloom’s Taxonomy: 3) Application
Learning Outcome: 10.2.5

65) Briefly discuss the role of the myosin heads in the sliding filament mechanism of muscle contraction.
Answer: The interaction of thin filaments sliding past thick filaments generates tension throughout the sarcomere during muscle contraction. This is known as the sliding filament mechanism. Myosin heads of the thick filaments grab active sites on thin filaments and pull the thin filaments toward the M line as the myosin heads rotate. The pulling action brings the Z discs closer together and shortens the sarcomere. Neither the thin nor the thick filaments actually shorten; instead the thin filaments are pulled and slide toward the M line.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.2.5

66) Explain where sodium and potassium ions are relative to a muscle cell during resting membrane potential.
Answer: A membrane is considered polarized in its resting state when opposite charges are located on either side of the membrane. At rest, the concentration of sodium ions is greater in the extracellular fluid and lower in the cytosol due to the actions of the Na+/K+ ATPase pump. Potassium ion concentration is higher in the cytosol and lower in the extracellular fluid at rest.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.3.1

67) Explain the role sodium ions play in the depolarization stage of the action potential.
Answer: Positively charged sodium ions make the membrane potential become less negative during depolarization. Sodium ions rush into a muscle cell with their concentration gradient when voltage-gated sodium ion channels open. The membrane potential reaches a peak of +30 mV.
Bloom’s Taxonomy: 3) Application
Learning Outcome: 10.3.4
68) Describe the synaptic cleft.
Answer: The synaptic cleft is the narrow gap of space between the axon terminal and the muscle fiber into which acetylcholine is released.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.4.1

69) Explain the role of acetylcholine in the excitation phase of excitation-contraction coupling.
Answer: Acetylcholine is a neurotransmitter responsible for triggering changes in skeletal muscle cells. When released by axon terminals into the synaptic cleft, acetylcholine binds to ligand-gated ion channels in the motor end plate of the skeletal muscle. Upon binding the receptors, sodium ion channels open and sodium ions enter the muscle fiber to produce a local depolarization in the skeletal muscle leading to the muscle cell’s action potential.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.4.2

70) Describe the role of calcium in the regulation of the troponin-tropomyosin complex.
Answer: Calcium binds troponin upon its release from the sarcoplasmic reticulum when the skeletal muscle fiber is excited. As a result of the binding, tropomyosin shifts and moves revealing active sites on actin. As the muscle relaxes, calcium ions are pumped back into the sarcoplasmic reticulum. Without calcium, troponin and tropomyosin return to their positions blocking the active sites on actin. Myosin heads are prevented from binding and muscle contraction is inhibited.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.4.4, 10.4.5

71) Summarize the steps of the crossbridge cycle.
Answer: During the crossbridge cycle, a myosin head binds to an active site on actin that leads to the sliding of myofilaments. ATP hydrolysis cocks the myosin head into its high energy position. ADP and a phosphate remain attached to the myosin head. The myosin head binds to an active site on actin. When ADP and the phosphate detach from the myosin head, the power stroke occurs in which myosin pulls actin toward the center of the sarcomere. ATP is needed for the release of the myosin head from actin so that this crossbridge cycle can repeat again.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.4.4

72) Explain why myoglobin is useful.
Answer: Myoglobin binds oxygen that has diffused into the muscle cell from the extracellular fluid. Oxygen is released from myoglobin as mitochondria perform oxidative catabolism. Oxidative catabolism utilizes oxygen to produce ATP. Thus myoglobin supplements oxygen delivery to mitochondria.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.5.2

73) Describe the events of the relaxation period of a muscle twitch.
Answer: During relaxation, tension decreases as calcium ions are pumped back into the sarcoplasmic reticulum (SR) for storage. Tropomyosin blocks the active sites on actin and the muscle relaxes. Tension eventually equals zero.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.6.1

74) Determine how muscles are affected if the muscle receives stimulations so frequently that it has no opportunity to relax between them.
Answer: Fused, or complete, tetanus can occur when a muscle receives no opportunity to relax between frequent stimulations. A sustained contraction occurs because the muscle cell has received a stimulus before the last twitch is over.
Bloom’s Taxonomy: 3) Application
Learning Outcome: 10.6.2

75) Discuss the type of contractions produced by type I muscle fibers.
Answer: Type I muscle fibers are slow-twitch fibers. Although contractions are slower and less forceful, Type I fibers can maintain contractions over extended periods of time as they are slow to fatigue.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.6.3

76) Determine the type of muscle contraction needed to lower a heavy bowling ball down by your side so you can roll it down the lane.
Answer: An isotonic eccentric contraction results in muscle lengthening and is the type of contraction that allows you to lower a heavy load. Motor units must generate tension while the sarcomere stretch and lengthen.
Bloom’s Taxonomy: 3) Application
Learning Outcome: 10.7.3

77) How does hypertrophy change a muscle? Briefly explain.
Answer: Hypertrophy is an increase in both the number of myofibrils and the diameter of the muscle fibers.
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.8.1

78) Skeletal muscle fibers possess intercalated discs.
Answer: FALSE
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.1.3

79) Contractility is the ability of a muscle to shorten.
Answer: FALSE
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.1.3

80) The function of the sarcoplasmic reticulum (SR) is to store and release calcium ions.
Answer: TRUE
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.1

81) The three types of myofilaments are thin, thick and elastic.
Answer: TRUE
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.3
82) In a sarcomere, the light and dark bands are produced by alternating M lines and Z discs.
Answer: FALSE
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.4

83) Myofilaments shorten to produce muscle contractions according to the sliding filament mechanism.
Answer: FALSE
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.2.5

84) Electrical gradients exist because sodium and potassium ions are separated on either side of the plasma membrane.
Answer: TRUE
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.3.2

85) The Na+/K+ ATPase (Na+/K+ pump) maintains the concentration gradients for sodium and potassium ions by moving two sodium ions out of the cell and three potassium ions into the cell.
Answer: FALSE
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.3.3

86) The loss of potassium ions from the cell during the repolarization stage restores a membrane potential of -85 mV.
Answer: TRUE
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.3.4

87) The entry of acetylcholine into a muscle cell through ligand-gated ion channels depolarizes the sarcolemma locally.
Answer: FALSE
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.4.2

88) ATP is required for a power stroke to be repeated during the contraction cycle.
Answer: TRUE
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.4.4

89) The return of calcium ions to the sarcoplasmic reticulum during muscle relaxation decreases the calcium ion concentration in the cytosol.
Answer: TRUE
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.4.5

90) Creatine phosphate provides 30-40 seconds of energy for muscle activity.
Answer: FALSE
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.5.3
91) Greater muscle tension results when muscle fibers are repeatedly stimulated.
Answer: TRUE
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.6.2

92) Type IIb fibers produce the fastest, strongest twitches of any fiber type.
Answer: TRUE
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.6.3

93) Cindy’s leg muscles displayed a state of hypotonia since her arm was recently removed from a cast.
Answer: TRUE
Bloom’s Taxonomy: 3) Application
Learning Outcome: 10.7.2

94) Both isotonic eccentric contractions and isotonic concentric contractions shorten the muscle.
Answer: FALSE
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.7.3

95) Jack has decided to take up jogging as a way to enhance his endurance training.
Answer: TRUE
Bloom’s Taxonomy: 3) Application
Learning Outcome: 10.8.1

96) Decreased oxygen availability leads to muscle fatigue.
Answer: TRUE
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.8.2

97) Cardiac muscles perform peristalsis to pump blood through the heart.
Answer: FALSE
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.9.1

Match the following:

A) elasticity
B) A band
C) extensibility
D) excitability
E) contractility
F) Z-disc
G) conductivity
H) H zone
I) I band
J) M line

98) Ability of muscle tissue to return to its original shape after being stretched
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.1.2

99) Ability of proteins within the muscle cells to draw together
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.1.2
100) Electrical changes travel along the plasma membrane
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.1.2

101) Ability of muscle cells to respond to stimuli
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.1.2

102) Ability of muscle cells to stretch
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.1.2

103) This structure attaches myofibrils to one another
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.2

104) Region that contains both thick and thin filaments
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.2

105) Thin and elastic filaments are anchored to this structure
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.2

106) Middle portion of the A band that contains thick filaments only
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.2

107) Middle line of the A band
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.2

108) Region that contains only thin filaments
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.2

109) The sarcomere is situated between two of these adjacent structures
Bloom’s Taxonomy: 1) Knowledge
Learning Outcome: 10.2.2
Answers: 98) A 99) E 100) G 101) D 102) C 103) F 104) B 105) F 106) H 107) J 108) I 109) F

110) On a laboratory exam, you are asked to identify various muscle tissues through the microscope. Describe the characteristics you will use to differentiate among the three types of muscle tissue.
Answer: First, look for light and dark bands known as striations to help you differentiate between striated muscle tissue (cardiac and skeletal) and non-striated muscle tissue (smooth). To determine the difference between the two types of striated muscle tissue, look for long, multinucleated cells that are arranged parallel to one another in skeletal muscle tissue. By contrast, cardiac muscle cells are shorter and wider, branched, and generally have only one or two nuclei. Intercalated discs are unique to cardiac muscle cells. Finally, non-striated muscle tissue is smooth muscle tissue. Smooth muscle cells are long and flattened with two pointed ends (spindle-shaped). These cells often have a single, centrally located oval nucleus.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.1.3

111) Describe the role of calcium in the crossbridge cycle of the sliding filament mechanism.
Answer: Calcium ions released from the sarcoplasmic reticulum bind to troponin. Upon binding, tropomyosin moves and the active sites of actin filaments are now exposed. Once the active sites are exposed, crossbridge formation may commence when myosin heads bind to the active sites on the actin filaments. A crossbridge cycle is now initiated in which the thick and thin filaments slide past one another.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.4.4

112) The nerve gas, sarin, was used during World War II as chemical warfare. Sarin inhibits the effects of acetylcholinesterase at the synapse. Predict how sarin will affect excitation.
Answer: Acetylcholinesterase promotes muscle relaxation by degrading acetylcholine that remains in the synaptic cleft. Acetylcholinesterase breaks down the acetylcholine into substances that can no longer stimulate the muscle. Without adequate acetylcholinesterase available to perform this job, acetylcholine will continue to excite the muscle cell by binding to ligand-gated sodium ion channels in the motor end plate. Ion channels will open and the entry of sodium ions into the muscle cell will create a local depolarization. Muscles will be unable to relax if acetylcholine is continually present in the synaptic cleft without the degrading effects of acetylcholinesterase.
Bloom’s Taxonomy: 3) Application
Learning Outcome: 10.4.5
113) Kelly is examining a myogram showing contractions of the gastrocnemius muscle. Assess how she should differentiate unfused (incomplete) tetanus from fused (complete) tetanus.
Answer: On the myogram, although maximum tension can be achieved, the muscle has opportunities to partially relax between contractions. Pulsating tension results (unfused tetanus) in which the muscle relaxes slightly, then tension increases a little more with each successive muscle twitch. Muscles experiencing fused tetanus have no opportunity for relaxation between stimuli since the stimuli arrive more frequently at the muscle (approximately 80-100 stimuli per second). On the myogram, maximum tension would be achieved through fused tetanus while the muscle experiences a sustained contraction without relaxation.
Bloom’s Taxonomy: 3) Application
Learning Outcome: 10.6.2

114) Gowoon wants to be a long-distance runner and participate in competitions on her high school track and field team. Describe the specific type of skeletal muscle fiber which will help her excel at her sport. What type of training should she perform to enhance the capabilities of this particular fiber type?
Answer: Type I fibers are slow-twitch fibers that can maintain extended periods of contraction. Since these fibers use large quantities of ATP to maintain contractions, they utilize oxidative catabolism. Oxidative catabolism can provide ATP for hours. Myoglobin present in these muscle fibers binds oxygen to help supply the oxidative generation of ATP. Gowoon should focus on endurance training which will result in an increase in the number of mitochondria and a greater blood supply (more blood vessels). Endurance training helps type I muscles utilize resources to make ATP and resist fatigue.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.6.3, 10.8.1

115) Mr. Bailey, a 58 year old man, wants to add muscle mass to his frame since he has noticed he is not as strong as he used to be. Discuss the type of physical training you have determined will help him add strength to his muscles. How will your choice help him achieve his goal? What muscle changes do you think he will experience as he begins your training?
Answer: Resistance training, or strength training, will help Mr. Bailey add strength to his muscles. Resistance training increases the number of myofibrils, therefore increasing the diameter of the muscle fibers. Thus, his muscles can hypertrophy with this type of exercise. To achieve his goal, Mr. Bailey should use free weights or a resistance-exercise machine. However, a trade-off of muscle hypertrophy is the loss of endurance that comes with the proportionally fewer mitochondria and blood vessels in the muscle tissue compared to the results of endurance training. If he chooses resistance training alone, he may experience a decreased capacity for endurance.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.8.1

116) What purpose do gap junctions serve in cardiac and smooth muscle tissues?
Answer: Gap junctions electrically link muscle cells together so that action potentials spread rapidly through the cells. Cells in single-unit smooth muscle contract together as a single unit due to the presence of gap junctions. By contrast, smooth muscle tissue that lacks these gap junctions do not work together and contract as a single unit. Cardiac muscle tissue possesses gap junctions to allow the heart to contract as a unit to act functionally as a pump.
Bloom’s Taxonomy: 2) Comprehension
Learning Outcome: 10.9.2