chapter 9_muscular system.txt

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chapter 9_muscular system.txt
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2010-11-29 01:18:47
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  1. a _______ _______ is an organ of the muscular system.
    skeletal muscle
  2. a skeletal muscle is composed of four things:
    • skeletal muscle tissue
    • nervous tissue
    • blood
    • connective tissue
  3. dense connective tissue that separates individual skeletal muscles
    fascia
  4. cordlike structure that consists of dense connective tissue
    tendon
  5. _______ connects a muscle to a bone
    tendon
  6. sheetlike structure composed of dense connective tissue
    aponeurosis
  7. layer of connective tissue that closely surrounds a skeletal muscle
    epimysium
  8. connective tissue that separates muscles into fascicles
    perimysium
  9. a section of a muscle
    fascicle
  10. connective tissue that surrounds individual muscle cells
    endomysium
  11. fascia that surrounds or penetrates muscles
    deep fascia
  12. fascia just beneath the skin
    subcutaneous fascia
  13. connective tissue layer of the serous membrane covering organs in various body cavities and lining those cavities
    subserous fascia
  14. a skeletal muscle fiber is a single muscle ____.
    cell
  15. the plasma membrane of the cell
    sarcolemma
  16. the cytoplasm of a muscle cell
    sarcoplasm
  17. the _________ contains many small nuclei, mitochondria, and myofibrils
    sarcoplasm
  18. threadlike structures that are located in the sarcoplasm
    myofibrils
  19. what fundamental role do myofibrils play in the muscle?
    muscle contraction
  20. thick myofilaments are composed of ___________.
    myosin
  21. thin filaments are composed of ______.
    actin
  22. the organization of __________ produces the alternating light and dark striation characteristic of skeletal muscles.
    myofilaments
  23. a repeating pattern of a myofibril
    sarcomere
  24. sarcomeres joined end to end are thought to be _______.
    myofibrils
  25. I bands are composed of _____ _______ ______
    thin actin filaments
  26. Z lines are structures that connect and anchor ____ ______
    I bands
  27. __ ______ are composed of thick myosin filaments overlapping thin actin filaments
    A bands
  28. the ___ ____ is a cenral region of an A band that only contains thick filaments
    H zone
  29. a region of an A band which consists of proteins that help hold the thick filaments in place
    M line
  30. _____ connects proteins that connect myosin filaments to Z lines
    Titin
  31. a ______ extends from one Z line to another Z line
    sarcomere
  32. each ___ ______ consists of two twisted protein strands with globular parts called cross-bridges that project outward along their lengths
    myosin molecule
  33. ___ ______ consist of double strands of actin twisted into a helix
    thin filaments
  34. actin has a ___ _____ to which the cross-bridges of a myosin molecule can attach
    binding site
  35. _______ and _______ associate with actin filaments
    troponin and tropomyosin
  36. endoplasic reticulum of a muscle fiber
    sarcoplasmic reticulum
  37. membranous channels that extend into the sarcoplasm as invaginations continous with the sarcolemma and contains extracellular fluid
    transverse tubules
  38. enlarged portions of sarcoplasmic reticulum
    cisternae
  39. a ____ is formed by one transverse tubule and two cisternae
    triad
  40. a motor neuron passes out from ___ or __ ___
    brain or spinal cord
  41. normally, a skeletal muscle fiber contracts only upon what?
    stimulation by a motor neuron
  42. the site where the axon and muscle fiber meet
    neuromuscular junction
  43. a specialized portion of the muscle cell membrane that is extensively folded
    motor end plate
  44. a motor neuron and the muscle fibers it controls
    motor unit
  45. separates the membranes of the neuron and the membrane of the muscle fiber
    synaptic cleft
  46. synaptic vesicles store ______________.
    neurotransmitters
  47. the neurotransmitter that motor neurons use to control skeletal muscle
    acetylcholine
  48. _____ is synthesized in the cytoplasm of the motor neuron and is stored in synaptic vesicles in axons.
    ACh
  49. when a nerve impulse reaches the end of an axon, __________ is released into the synaptic cleft.
    acetylcholine
  50. ___ combines with ACh receptors on the motor end plate, and stimulates the muscle fiber
    ACh
  51. an electrical signal that is like a nerve impulse
    muscle impulse
  52. a ____ _____ changes the muscle cell membrane in a way that transmits the impulse in all directions along and around the muscle cell
    muscle impulse
  53. where does the muscle impulse ultimately reach?
    sarcoplasmic reticulum and cisternae
  54. the __________ ___________ has a high concentration of calcium
    sarcoplasmic reticulum
  55. in response to a muscle impulse, the membranes become more ______ to calcium, and the calcium ______ out of the cisternae into the cytosol of the muscle fiber.
    • permeable
    • diffuses
  56. when a muscle fiber is at rest, the _____-_______ complexes block the binding sites on the actin molecules
    troponin-tropomyosin
  57. calcium ions bind to ______, changing its shape and altering the position of the tropomyosin
    troponin
  58. the movement of the tropomyosin molecule ________________________________, allowing linkages to form between myosin cross-bridges and actin.
    exposes the binding sites of the actin filaments
  59. the functional unit of skeletal muscles
    sarcomere
  60. according to the sliding filament theory, when sarcomeres shorten, the thick and thin filaments ______________________.
    slide past one another
  61. as contraction occurs, the H zones and I bands get ________, and the Z lines move ___________.
    • narrower
    • closer together
  62. the force that shortens the sarcomeres comes from ___________________________.
    cross-bridges pulling on the actin filaments.
  63. a _______________ attaches to actin in order to pull on the actin filament.
    myosin cross-bridge
  64. myosin cross-bridges contain the enzyme ________.
    ATPase
  65. ATPase catalyzes the breakdown of ____ to ____.
    ATP to ADP
  66. the force of muscle contraction is provided by the ____________________.
    breakdown of ATP into ADP.
  67. breaking down of ATP puts the myosin cross-bridge into a "______" position
    cocked
  68. when a muscle is stimulated to _______, a cocked cross-bridge attaches to actin and pulls the actin filament toward the center of the sarcomere, shortening the muscle.
    contract
  69. when another ATP binds, the _________ is released, and then breaks down the ATP to return to the cocked position.
    cross-bridge
  70. in order for a muscle fiber to relax, acetylcholine must be decomposed by an enzyme called ________.
    acetylcholinesterase
  71. the action of acetylcholinesterase prevents a single nerve impulse from continuously __________________.
    stimulating a muscle fiber
  72. moves calcium back into the sarcoplasmic reticulum
    calcium pump
  73. when calcium is removed from the cytoplasm, the cross-bridge linkages break and tropomyosin rolls back into its groove, preventing any _______________________.
    cross-bridge attachment
  74. _____ is necessary for both muscle contraction and relaxation
    ATP
  75. the _____________________ is the increase in cytosolic calcium in response to stimulation by ACh from a motor neuron.
    trigger for contraction
  76. energy source available to generate ATP from ADP.
    creatine phosphate
  77. contains a high energy phosphate bond
    creatine phosphate
  78. after creatine phosphate is used, a muscle cell must depend on _________________________ as a source of energy for synthesizing ATP.
    cellular respiration of glucose
  79. typically, a muscle stores glucose in the form of ________.
    glycogen
  80. occurs in the cytoplasm and is anaerobic
    glycolysis
  81. the complete breakdown of glucose occurs in __________ and requires __________.
    • mitochondria
    • oxygen
  82. the citric acid cycle and electron transport chain produce _______, ____________, and a large amount of _______.
    • water
    • carbon dioxide
    • ATP
  83. _______ is carried in the blood stream bound to hemoglobin.
    oxygen
  84. _________- stores oxygen in muscle tissue
    myoglobin
  85. rapid increase in blood levels of lactic acid
    lactic acid threshold
  86. under _________conditions, glycolysis breaks down glucose into pyruvic acid and converts it to lactic acid.
    anaerobic
  87. carried by the blood to the liver
    lactic acid
  88. ____________ can convert lactic acid to glucose.
    liver cells
  89. condition in which a muscle fiber cannot contract.
    fatigue
  90. __________--- may result from decreased blood flow, ion imbalances across the sarcolemma, and the psychological loss of the desire to exercise
    fatigue
  91. a painful condition in which a muscle undergoes a sustained, involuntary contraction.
    cramp
  92. _____ is a by-product of cellular respiration
    heat
  93. _____ transports heat throughout the body, which helps to maintain body temperature.
    blood
  94. the minimal stimulus needed to start a muscle contraction
    threshold stimulus
  95. the response of a single muscle fiber to the ACh released by a single action potential
    twitch
  96. a recording of the events of a muscle twitch
    myogram
  97. three periods of a muscle fiber contraction are
    • latent
    • contraction
    • relaxation
  98. during a period of contraction, a muscle fiber is generating force or ___________.
    contracting
  99. the period before contraction
    latent period
  100. the period in which a muscle fiber is decreasing tension
    period of relaxation
  101. the period in which a muscle fiber is unresponsive to stimulation
    refractory period
  102. a response in which a muscle fiber contracts completely or not at all
    all-or-none response
  103. if a muscle is stretched well beyond its normal resting length, the force will ________.
    decrease
  104. the combination of the force of individual twitches
    summation
  105. contractions that lack relaxation
    tetanic contractions
  106. the ______ ____ ___ in the motor units, the more precise the movements can be produced in a particular muscle.
    fewer muscle fibers
  107. all muscle fibers in a motor unit are stimulated at _______.
    the same time
  108. multiple motor unit summation is _____________.
    recruitment
  109. an increase in the number of activated motor units
    recruitment
  110. an increase in the number of activated motor units
    recruitment
  111. _______ motor units respond later and more forcefully
    larger
  112. muscle movements are smooth because_____________________________________________________________________.
    the spinal cord stimulates contraction in different set of motor units at different times.
  113. the amount of sustained contractions in a muscle
    muscle tone
  114. muscle tone is important for maintaining __________.
    posture
  115. a type of contraction that produces movement of a body part.
    isotonic contraction
  116. an isotonic contraction in which shortening of the muscle occurs.
    concentric contraction
  117. an isotonic contraction in which lengthening of the muscle occurs
    eccentric
  118. a contraction in which muscle tension increases but no movements of body parts are produced.
    isometric contractions
  119. an example of an isometric contraction
    standing
  120. an example of an isotonic contraction
    walking
  121. type I fibers are _________ fibers
    low-twitch
  122. type I fibers are resistant to ________.
    fatigue
  123. type IIa fibers are fast twitch _____ fibers.
    glycolytic fibers.
  124. type IIb fibers are fast twitch ______ fibers
    oxidative fibers
  125. two major types of smooth muscle
    • visceral
    • multiunit
  126. where is multiunit smooth muscle found?
    in the irises and walls of blood vessels.
  127. where is visceral smooth muscle located?
    walls of hollow organs except for the heart
  128. fibers of viscera; smooth muscle are connected by ________.
    gap junctions
  129. a pattern of spontaneous repeated contractions
    rythmicity
  130. wavelike motion produced by smooth muscle contraction
    peristalsis
  131. what does peristalsis do?
    helps force the contents of a tube along its length.
  132. two neurotransmitters that affect smooth muscle
    • acetylcholine
    • norepinephrine
  133. hormones effect smooth muscle in two ways
    • by stimulating or inhibiting contraction
    • lettering the degree of response to neurotransmitters
  134. stretching of smooth muscle can trigger ______.
    contractions
  135. smooth muscle is _____ to contract and to relax then skeletal muscle
    slower
  136. unlike skeletal muscle, smooth muscle fibers can change ___ without changing _____.
    • length
    • tautness

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