Author:
lonelygirl
ID:
220093
Filename:
Chapter 9 Muscles and Muscles Tissue (Mastering A&P)
Updated:
2013-05-18 00:44:29
Tags:
Biology Anatomy Physiology
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Description:
Biology 103A
Show Answers:

  1. Which of the following is CORRECTLY paired?

    A. cardiac muscle: nonstriated
    B. smooth muscle: striated
    C. skeletal muscle: voluntary control
    D. cardiac muscle: voluntary control
    C. skeletal muscle: voluntary control
  2. What causes the release of calcium from the terminal cisternae of the sarcoplasmic reticulum within a muscle cell?

    A. calcium ion pump
    B. ATP
    C. troponin
    D. arrival of an action potential
    D. arrival of an action potential
    (this multiple choice question has been scrambled)
  3. The binding of calcium to which molecule causes the myosin binding sites to be exposed?

    A. tropomyosin
    B. troponin
    C. actin
    B. troponin
    (this multiple choice question has been scrambled)
  4. A myosin head binds to which molecule to form a cross bridge?

    A. tropomyosin
    B. troponin
    C. actin
    C. actin
    (this multiple choice question has been scrambled)
  5. What causes the myosin head to disconnect from actin?

    A. binding of calcium
    B. binding of troponin
    C. binding of ATP
    D. hydrolysis of ATP
    C. binding of ATP
    (this multiple choice question has been scrambled)
  6. What energizes the power stroke?

    A. hydrolysis of ATP
    B. calcium
    C. binding of ATP
    A. hydrolysis of ATP
    (this multiple choice question has been scrambled)
  7. In a neuromuscular junction, synaptic vesicles in the motor neuron contain which neurotransmitter?

    A. serotonin
    B. norepinephrine
    C. acetylcholine (ACh)
    D. dopamine
    C. acetylcholine (ACh)
    (this multiple choice question has been scrambled)
  8. When an action potential arrives at the axon terminal of a motor neuron, which ion channels open?

    A. chemically gated calcium channels
    B. voltage-gated calcium channels
    C. voltage-gated potassium channels
    D. voltage-gated sodium channels
    B. voltage-gated calcium channels
    (this multiple choice question has been scrambled)
  9. What means of membrane transport is used to release the neurotransmitter into the synaptic cleft?

    A. a protein carrier
    B. a channel
    C. exocytosis
    C. exocytosis
    (this multiple choice question has been scrambled)
  10. The binding of the neurotransmitter to receptors on the motor end plate causes which of the following to occur?

    A. Binding of the neurotransmitter causes chemically gated sodium channels to open in the motor end plate.
    B. Binding causes voltage-gated sodium channels to open in the motor endplate.
    C. Binding causes chemically gated potassium channels to open in the motor end plate.
    D. Binding causes potassium voltage-gated channels to open in the motor endplate.
    A. Binding of the neurotransmitter causes chemically gated sodium channels to open in the motor end plate.
    (this multiple choice question has been scrambled)
  11. How is acetylcholine (ACh) removed from the synaptic cleft?

    A. acetylcholinesterase (AChE; an enzyme)
    B. diffusion away from the synaptic cleft
    C. a reuptake pump on the axon terminal
    A. acetylcholinesterase (AChE; an enzyme)
    (this multiple choice question has been scrambled)
  12. The action potential on the muscle cell leads to contraction due to the release of calcium ions. Where are calcium ions stored in the muscle cell?

    A. cytosol
    B. terminal cisternae of the sarcoplasmic reticulum
    C. sarcolemma
    D. T tubule
    B. terminal cisternae of the sarcoplasmic reticulum
    (this multiple choice question has been scrambled)
  13. Excitation-contraction coupling is a series of events that occur after the events of the
    neuromuscular junction have transpired. The term excitation refers to which step in the process?

    A. Excitation refers to the shape change that occurs in voltage-sensitive proteins in the sarcolemma.
    B. Excitation refers to the release of calcium ions from the sarcoplasmic reticulum.
    C. Excitation, in this case, refers to the propagation of action potentials along the sarcolemma.
    D. Excitation refers to the propagation of action potentials along the axon of a motor neuron.
    D. Excitation refers to the propagation of action potentials along the axon of a motor neuron.
  14. Excitation of the sarcolemma is coupled or linked to the contraction of a skeletal muscle fiber. What specific event initiates the contraction?

    A. Voltage-sensitive proteins change shape.
    B. Action potentials propagate into the interior of the skeletal muscle fiber.
    C. Sodium release from the sarcoplasmic reticulum initiates the contraction.
    D. Calcium release from the sarcoplasmic reticulum initiates the contraction.
    D. Calcium release from the sarcoplasmic reticulum initiates the contraction.
    (this multiple choice question has been scrambled)
  15. A triad is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum. How are these components connected?

    A. Potassium leak channels.
    B. Myosin cross-bridge binding sites.
    C. A series of proteins that control calcium release.
    D. Voltage-gated sodium channels.
    C. A series of proteins that control calcium release.
    (this multiple choice question has been scrambled)
  16. What is name given to the regularly spaced infoldings of the sarcolemma?

    A. sarcoplasmic reticulum
    B. motor endplates
    C. terminal cisternae
    D. transverse or T tubules
    D. transverse or T tubules
    (this multiple choice question has been scrambled)
  17. Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers?

    A. Calcium ions.
    B. Acetylcholine.
    C. Action potentials.
    D. Sodium ions.
    A. Calcium ions.
  18. What is the relationship between the number of motor neurons recruited and the number of skeletal muscle fibers innervated?

    A. A motor neuron typically innervates only one skeletal muscle fiber.
    B. Typically, hundreds of skeletal muscle fibers are innervated by a single motor neuron.
    C. Motor neurons always innervate thousands of skeletal muscle fibers.
    D. A skeletal muscle fiber is innervated by multiple motor neurons.
    B. Typically, hundreds of skeletal muscle fibers are innervated by a single motor neuron.
    (this multiple choice question has been scrambled)
  19. Excitation-contraction coupling includes all EXCEPT which of the following events?

    A. propagation of an action potential along the sarcolemma and down T tubules
    B. binding of calcium ions to troponin, which removes the blocking action of tropomyosin
    C. release of acetylcholine from axon terminals at the neuromuscular junction
    D. release of calcium ions from the terminal cisterns
    C. release of acetylcholine from axon terminals at the neuromuscular junction
  20. What is a cross bridge cycle?

    A. It is the cycle by which the sarcolemma is repeatedly depolarized and repolarized.
    B. It is a cycle of repeated stimuli resulting in summation of muscle twitches.
    C. It is the cycle in which motor units are recruited from small to large, in order to produce gradual increases in force.
    D. It is the cycle in which an energized myosin head binds to actin and performs a power stroke, then binds to ATP in order to detach and re-energize.
    D. It is the cycle in which an energized myosin head binds to actin and performs a power stroke, then binds to ATP in order to detach and re-energize.
  21. Muscle tissue does NOT ________.

    A. produce movement
    B. generate heat
    C. produce blood cells
    D. maintain posture
    E. stabilize joints
    C. produce blood cells
  22. Which type of muscle CANNOT contract without being stimulated by the nervous system?

    A. skeletal
    B. cardiac
    C. smooth
    D. visceral
    A. skeletal
  23. Which muscle characteristic describes the ability of muscle to respond to a stimulus?

    A. excitability
    B. contractility
    C. extensibility
    D. elasticity
    A. excitability
  24. Action potential propagation in a skeletal muscle fiber ceases when acetylcholine is removed from the synaptic cleft. Which of the following mechanisms ensures a rapid
    and efficient removal of acetylcholine?

    A. Acetylcholine diffuses away from the cleft.
    B. Acetylcholine is degraded by acetylcholinesterase.
    C. Acetylcholine is transported into the postsynaptic neuron by receptor-mediated endocytosis.
    D. Acetylcholine is transported back into the axon terminal by a reuptake mechanism.
    B. Acetylcholine is degraded by acetylcholinesterase.
    (this multiple choice question has been scrambled)
  25. The neuromuscular junction is a well-studied example of a chemical synapse. Which of the following statements describes a critical event that occurs at the neuromuscular junction?

    A. Acetylcholine is released and moves across the synaptic cleft bound to a transport protein.
    B. Acetylcholine is released by axon terminals of the motor neuron.
    C. Acetylcholine binds to its receptor in the junctional folds of the sarcolemma. Its receptor is linked to a G protein.
    D. When the action potential reaches the end of the axon terminal, voltage-gated sodium channels open and sodium ions diffuse into the terminal.
    B. Acetylcholine is released by axon terminals of the motor neuron.
    (this multiple choice question has been scrambled)
  26. Action potentials travel the length of the axons of motor neurons to the axon terminals. These motor neurons __________.

    A. extend from the spinal cord to the sarcolemma of a skeletal muscle fiber
    B. extend from the brain to the sarcolemma of a skeletal muscle fiber
    C. extend from the brain or spinal cord to the sarcolemma of a skeletal muscle fiber
    D. arise in the epimysium of a skeletal muscle and extend to individual skeletal muscle fibers
    C. extend from the brain or spinal cord to the sarcolemma of a skeletal muscle fiber
    (this multiple choice question has been scrambled)
  27. Calcium entry into the axon terminal triggers which of the following events?

    A. Synaptic vesicles fuse to the plasma membrane of the axon terminal and release acetylcholine.
    B. Acetylcholine binds to its receptor.
    C. Acetylcholine is released into the cleft by active transporters in the plasma membrane of the axon terminal.
    D. Cation channels open and sodium ions enter the axon terminal while potassium ions exit the axon terminal.
    A. Synaptic vesicles fuse to the plasma membrane of the axon terminal and release acetylcholine.
    (this multiple choice question has been scrambled)
  28. Acetylcholine binds to its receptor in the sarcolemma and triggers __________.

    A. the opening of ligand-gated cation channels
    B. the opening of calcium-release channels
    C. the opening of ligand-gated anion channels
    D. the opening of voltage-gated calcium channels
    A. the opening of ligand-gated cation channels
    (this multiple choice question has been scrambled)
  29. Sodium and potassium ions do not diffuse in equal numbers through ligand-gated cation channels. Why?

    A. The inside surface of the sarcolemma is negatively charged compared to the outside surface. Sodium ions diffuse inward along favorable chemical and electrical gradients.
    B. The inside surface of the sarcolemma is negatively charged compared to
    the outside surface. Potassium ions diffuse inward along favorable chemical and electrical gradients.
    C. The outside surface of the sarcolemma is negatively charged compared to the inside surface. Sodium ions diffuse outward along favorable chemical and electrical gradients.
    D. The outside surface of the sarcolemma is negatively charged compared to the inside surface. Potassium ions diffuse outward along favorable chemical and electrical gradients.
    A. The inside surface of the sarcolemma is negatively charged compared to the outside surface. Sodium ions diffuse inward along favorable chemical and electrical gradients.
  30. The cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. What is a cross bridge?

    A. ATP bound to a myosin head
    B. A myosin head bound to actin
    C. Calcium bound to troponin
    D. Troponin bound to tropomyosin
    B. A myosin head bound to actin
    (this multiple choice question has been scrambled)
  31. What structure is the functional unit of contraction in a skeletal muscle fiber?

    A. The triad
    B. The sarcomere
    C. The junctional folds of the sarcolemma
    D. The cross bridge
    B. The sarcomere
    (this multiple choice question has been scrambled)
  32. Calcium ions couple excitation of a skeletal muscle fiber to contraction of the fiber. Where are calcium ions stored within the fiber?

    A. Calcium ions are stored in the nuclei.
    B. Calcium ions are stored in the transverse tubules.
    C. Calcium ions are stored in the mitochondria.
    D. Calcium ions are stored in the sarcoplasmic reticulum.
    D. Calcium ions are stored in the sarcoplasmic reticulum.
    (this multiple choice question has been scrambled)
  33. After a power stroke, the myosin head must detach from actin before another power stroke can occur. What causes cross bridge detachment?

    A. Calcium ions bind to troponin.
    B. ADP and inorganic phosphate are bound to the myosin head.
    C. ATP binds to the myosin head.
    D. Acetylcholine binds to receptors in the junctional folds of the sarcolemma.
    C. ATP binds to the myosin head.
    (this multiple choice question has been scrambled)
  34. How does the myosin head obtain the energy required for activation?

    A. The energy comes from the direct phosphorylation of ADP by creatine phosphate.
    B. The energy comes from the hydrolysis of ATP.
    C. The energy comes from the hydrolysis of GTP.
    D. The energy comes from oxidative phophorylation.
    B. The energy comes from the hydrolysis of ATP.
    (this multiple choice question has been scrambled)
  35. What specific event triggers the uncovering of the myosin binding site on actin?

    A. Calcium release channels open in the sarcoplasmic reticulum, and calcium levels rise in the sarcoplasm.
    B. Sodium ions bind to troponin and change its shape.
    C. Calcium ions bind to tropomyosin and change its shape.
    D. Calcium ions bind to troponin and change its shape.
    D. Calcium ions bind to troponin and change its shape.
    (this multiple choice question has been scrambled)
  36. When does cross bridge cycling end?

    A. Cross bridge cycling ends when calcium release channels in the sarcoplasmic reticulum open.
    B. Cross bridge cycling ends when calcium ions are passively transported back into the sarcoplasmic reticulum.
    C. Cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin.
    D. Cross bridge cycling ends when ATP binds to the myosin head.
    C. Cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin.
  37. In the figure above, which structure corresponds to a single skeletal muscle cell?



    A. B
    B. D
    C. A
    D. C
    D. C
    (this multiple choice question has been scrambled)
  38. The connective tissue that covers structure A is continuous with which of the following?



    A. tendon
    B. sarcolemma
    C. endomysium
    D. ligament
    A. tendon
  39. Which structure corresponds to a single fascicle?



    A. A
    B. B
    C. C
    D. D
    B. B
  40. Which of the following is the smallest structural unit in which the distinctive striated bands characteristic of skeletal muscle are observed?



    A. B
    B. D
    C. A
    D. C
    B. D
    (this multiple choice question has been scrambled)
  41. The smallest contractile unit within skeletal muscle would correspond to the distance between which two points in the figure?


    A. 3 and 5
    B. 1 and 7
    C. 2 and 6
    D. 1 and 3
    B. 1 and 7
  42. Between which two points would there be substantial amounts of both the proteins actin and myosin?


    A. 2 and 3
    B. 1 and 2
    C. 3 and 5
    D. None of the listed responses is correct.
    A. 2 and 3
  43. The region between which two points corresponds to the I band?


    A. 3 and 5
    B. 2 and 5
    C. 2 and 3
    D. None of the listed responses is correct.
    D. None of the listed responses is correct.
  44. What cellular event is indicated by A?



    A. facilitated diffusion
    B. active transport
    C. endocytosis
    D. exocytosis
    D. exocytosis
  45. What event directly triggers the release of neurotransmitter shown in A?



    A. diffusion of K+ into the axonal terminus
    B. diffusion of Na+ out of the axonal terminus
    C. diffusion of Ca2+ into the axonal terminus
    D. diffusion of Na+ into the axonal terminus
    C. diffusion of Ca2+ into the axonal terminus
  46. What specific neurotransmitter is released from the axonal terminus as shown in A?



    A. myosin
    B. calcium
    C. actin
    D. acetylcholine
    D. acetylcholine
  47. Which statement accurately describes the event indicated by B?



    A. Diffusion of Ca2+ into the muscle fiber triggers the diffusion of acetylcholine out of the muscle fiber.
    B. Binding of acetylcholine to a receptor triggers the opening of an ion channel.
    C. Diffusion of acetylcholine into the muscle fiber triggers the opening of an ion channel.
    D. Diffusion of acetylcholine into the muscle fiber triggers the diffusion of Ca2+ out of the muscle fiber.
    B. Binding of acetylcholine to a receptor triggers the opening of an ion channel.
  48. Which event is most significant in initiating the "wave of depolarization" shown in event C?



    A. diffusion of Na+ into the muscle fiber
    B. diffusion of K+ out of the muscle fiber
    C. diffusion of acetylcholine down the length of the muscle fiber
    D. diffusion of acetylcholine into the muscle fiber
    A. diffusion of Na+ into the muscle fiber
  49. The protein actin is indicated by which letter?



    A. B
    B. D
    C. A
    D. C
    C. A
    (this multiple choice question has been scrambled)
  50. Which protein is indicated by E?



    A. actin
    B. troponin
    C. tropomyosin
    D. myosin
    D. myosin
  51. The molecular interaction described as a "cross bridge" involves the binding of which two of the letters below?



    A. B and D
    B. A and C
    C. A and B
    D. A and D
    B. A and C
  52. Which lettered protein functions as a motor protein?



    A. B
    B. D
    C. A
    D. C
    D. C
    (this multiple choice question has been scrambled)
  53. The protein troponin is shown in this figure to be bound to which substance?

    A. myosin
    B. acetycholine
    C. calcium ion
    D. sodium ion
    C. calcium ion
    (this multiple choice question has been scrambled)
  54. In which phase in the figure would the net movement of Ca2+ into the sarcoplasmic reticulum (SR) be greatest?



    A. B
    B. C
    C. A
    B. C
    (this multiple choice question has been scrambled)
  55. Which of the following is true concerning the anatomy of a skeletal muscle fiber?

    A. T tubules are extensions of the sarcoplasmic reticulum.
    B. Myofibrils contain thick and thin filaments.
    C. The sarcolemma is the muscle fiber’s cytoplasm.
    D. A triad consists of a T tubule and the nearby sarcolemma.
    B. Myofibrils contain thick and thin filaments.
    (this multiple choice question has been scrambled)
  56. The calcium that initiates skeletal muscle contraction is released from what structure(s)?

    A. sarcolemma
    B. T tubules
    C. sarcomeres
    D. terminal cisternae
    D. terminal cisternae
    (this multiple choice question has been scrambled)
  57. Which of the following are composed of myosin?

    A. tropomyosin
    B. intermediate filaments
    C. thick filaments
    D. thin filaments
    C. thick filaments
    (this multiple choice question has been scrambled)
  58. In muscle fibers, which regulatory protein blocks the attachment of myosin heads to actin?

    A. thick filaments
    B. acetylcholinesterase
    C. calcium
    D. tropomyosin
    D. tropomyosin
    (this multiple choice question has been scrambled)
  59. What event most directly triggers the release of calcium from the terminal cisternae?

    A. action potential propagating toward the axon terminal
    B. movement of tropomyosin away from the active sites on actin
    C. cross bridge formation between the thick and thin filaments
    D. action potential propagating down the T tubule
    D. action potential propagating down the T tubule
    (this multiple choice question has been scrambled)
  60. How do calcium ions initiate contraction in skeletal muscle fibers?

    A. Calcium ions provide the energy necessary for the myosin head power stroke.
    B. Calcium ions bind to tropomyosin, exposing the active sites on actin.
    C. Calcium ions bind to troponin, changing troponin’s shape.
    D. Calcium ion movement depolarizes the sarcolemma at the synaptic cleft.
    C. Calcium ions bind to troponin, changing troponin’s shape.
    (this multiple choice question has been scrambled)
  61. Which of the following best describes the events of “excitation” in “excitation-contraction coupling”?

    A. movement of tropomyosin away from the active sites on actin
    B. propagation of the action potential along the sarcolemma
    C. release of calcium from the terminal cisternae
    D. cross bridge formation
    B. propagation of the action potential along the sarcolemma
    (this multiple choice question has been scrambled)
  62. Which of the following best describes the events of “contraction” in “excitation-contraction coupling”?

    A. cross bridge formation
    B. propagation of the action potential along the sarcolemma of the muscle fiber
    C. release of calcium from the terminal cisternae
    D. sliding of myofilaments
    A. cross bridge formation
    (this multiple choice question has been scrambled)
  63. Isometric contraction leads to movement of a load. True or False
    False
  64. Thick myofilaments are made of ________.

    A. myosin
    B. tropomyosin
    C. troponin
    D. actin
    A. myosin
  65. Which pathway for regenerating ATP provides the majority of the energy used for muscle activity during 30 minutes of light to moderate exercise?

    A. aerobic respiration
    B. use of stored ATP
    C. anaerobic glycolysis
    D. direct phosphorylation of ADP by creatine phosphate
    A. aerobic respiration
  66. The type of muscle found in the walls of most hollow organs is ________.

    A. skeletal muscle
    B. cardiac muscle
    C. unitary smooth muscle
    D. multi unit smooth muscle
    C. unitary smooth muscle
  67. A muscle that is lengthening while it produces tension is performing a(an) ________ contraction.

    A. isometric
    B. maximal
    C. eccentric
    D. concentric
    C. eccentric
  68. The first step toward generating a skeletal muscle contraction is ________.

    A. binding of the myosin heads to actin
    B. stimulation of the muscle by a nerve ending
    C. binding of ATP to the myosin heads
    D. a rise in intracellular Ca2+ levels
    B. stimulation of the muscle by a nerve ending
  69. Which muscle fiber type is best suited for endurance activities, such as long-distance jogging?

    A. fast oxidative fibers
    B. fast glycolytic fibers
    C. slow glycolytic fibers
    D. slow oxidative fibers
    D. slow oxidative fibers
  70. What is the type of chemical reaction used to rebuild ADP into ATP?

    A. rehydration synthesis
    B. hydrolysis
    C. dehydration synthesis
    C. dehydration synthesis
    (this multiple choice question has been scrambled)
  71. Which of the following processes produces molecules of ATP and has two pyruvic acid molecules as end products?

    A. Krebs cycle and oxidative phosphorylation
    B. hydrolysis of creatine phosphate
    C. glycolysis
    C. glycolysis
    (this multiple choice question has been scrambled)
  72. Which of the following processes produces 36 ATP?

    A. Krebs cycle and oxidative phosphorylation
    B. hydrolysis of creatine phosphate
    C. glycolysis
    A. Krebs cycle and oxidative phosphorylation
    (this multiple choice question has been scrambled)
  73. The "rest and recovery" period, where the muscle restores depleted reserves, includes all of the following processes EXCEPT __________.

    A. ATP is used to rephosphorylate creatine into creatine phosphate.
    B. Pyruvic acid is converted back to lactic acid.
    C. Glycogen is synthesized from glucose molecules.
    D. Oxygen rebinds to myoglobin.
    B. Pyruvic acid is converted back to lactic acid.
    (this multiple choice question has been scrambled)
  74. Which type of muscle fiber has a large quantity of glycogen and mainly uses glycolysis to synthesize ATP?

    A. white fast twitch fibers
    B. red slow twitch fibers
    A. white fast twitch fibers
  75. In which phase of the muscle twitch shown in the above figure would the maximum amount of ATP be consumed by myosin head groups?



    A. B
    B. C
    C. A
    A. B
    (this multiple choice question has been scrambled)
  76. When muscle cells break down glucose to generate ATP under oxygen deficient conditions, they will form ________.

    A. glucose
    B. fatty acids
    C. lactic acid
    D. glycogen
    C. lactic acid
  77. The force of a muscle contraction is NOT affected by __________.

    A. the number of muscle fibers stimulated
    B. the frequency of the stimulation
    C. the size of the muscle fibers stimulated
    D. the degree of muscle stretch
    E. the amount of ATP stored in the muscle cells
    E. the amount of ATP stored in the muscle cells
  78. Cross bridge formation between myosin heads and actin molecules is caused by the elevation of calcium ion concentration in the cytosol. During rigor mortis, this elevation of calcium ion concentration in the cytosol is permanent because ________.

    A. mitochondria stop producing ATP molecules required by the sarcoplasmic reticulum's calcium ion pumps
    B. troponin molecules bind irreversibly to calcium ions to prevent them from being removed from the cytosol
    C. tropomyosin molecules bind irreversibly to calcium ions to prevent them from being removed from the cytosol
    D. acetylcholine continues to stimulate the release of calcium ions from the sarcoplasmic reticulum
    A. mitochondria stop producing ATP molecules required by the sarcoplasmic reticulum's calcium ion pumps
  79. The sliding filament model of contraction states that ________.

    A. during contraction the thin myofilaments slide past the thick myofilaments so that calcium ions can be released from the sarcoplasmic reticulum
    B. during contraction the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments no longer overlap
    C. during contraction the thin myofilaments slide past T tubules so that the Z discs are overlapping
    D. during contraction the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments overlap to a greater degree
    D. during contraction the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments overlap to a greater degree
  80. The distance between Z discs ________ during muscle contraction.

    A. increases
    B. decreases
    C. decreases and then increases
    D. stays the same
    B. decreases
  81. Which protein inhibits interaction between actin and myosin to prevent skeletal muscle contraction; and which ions remove the
    inhibition?

    A. tropomyosin; calcium ions
    B. myosin; sodium ions
    C. troponin; sodium ions
    D. actin; calcium ions
    A. tropomyosin; calcium ions
  82. The response of a motor unit to a single action potential of its motor neuron is called ________.

    A. a muscle twitch
    B. recruitment
    C. wave summation
    D. a tetanic contraction
    A. a muscle twitch
  83. What result would be expected if an additional stimulus, equal in intensity to the first, were to be applied to the muscle at the 60 millisecond (ms) time point?



    A. Tension would increase to the same maximum force measured at the beginning of phase C.
    B. The muscle would quickly return to the fully relaxed state of minimum tension.
    C. The muscle would increase in tension to a level greater than that measured at the beginning of phase C.
    D. The tension exerted by the muscle would continue to decrease, but at a significantly slower rate than observed without the second stimulus.
    C. The muscle would increase in tension to a level greater than that measured at the beginning of phase C.
  84. Slow oxidative muscle fibers are best suited for ________.

    A. running a marathon
    B. running a 100-yard dash
    C. hitting a baseball
    D. lifting heavy weights at the gym
    A. running a marathon
  85. Choose the FALSE statement.

    A. Skeletal muscle cells have glycosomes.
    B. Skeletal muscle cells use creatine phosphate instead of ATP to do work.
    C. Skeletal muscle cells have T tubules.
    D. Skeletal muscle cells are multinucleated.
    E. Skeletal muscle cells contain myoglobin.
    B. Skeletal muscle cells use creatine phosphate instead of ATP to do work.
  86. What special feature of smooth muscle allows it to stretch without immediately resulting in a strong contraction?

    A. stress-relaxation response
    B. low energy requirements
    C. slow, prolonged contractile activity
    D. smooth muscle tone
    A. stress-relaxation response
  87. The smallest contractile unit of a muscle fiber is ________.

    A. the elastic filament
    B. troponin
    C. the sarcomere
    D. the myofilament
    C. the sarcomere
  88. Cardiac muscle makes most of its ATP via anaerobic pathways. True or False
    False; aerobic
  89. Binding of calcium to calmodulin is a step in excitation-contraction coupling of ________ cells.

    A. smooth muscle
    B. skeletal muscle
    C. cardiac muscle
    D. cardiac and visceral smooth muscle
    A. smooth muscle
  90. Smooth muscles are able to regenerate throughout life. True or False
    True
  91. Which of the following is TRUE?

    A. Skeletal muscle fibers tend to be shorter than smooth muscle fibers.
    B. Skeletal muscle fibers contain sarcomeres; smooth muscle fibers do not.
    C. Skeletal muscle cells have one nucleus, but smooth muscle cells are multinucleated.
    D. Skeletal muscle lacks the coarse connective tissue sheaths that are found in smooth muscle.
    B. Skeletal muscle fibers contain sarcomeres; smooth muscle fibers do not.
  92. Which of the following factors influence the velocity and duration of muscle contraction?

    A. length of muscle fibers activated
    B. frequency of stimulation
    C. load placed on the muscle
    D. muscle fiber size
    C. load placed on the muscle
  93. The major role of the sarcoplasmic reticulum is to regulate ________.

    A. intracellular levels of Na+
    B. extracellular levels of Ca2+
    C. extracellular levels of Na+
    D. intracellular levels of Ca2+
    D. intracellular levels of Ca2+