Human AP 4.1

  1. Axon terminal
    when the end of and axon swells to form and axon terminal or synaptic bulb
  2. synaptic vesicles
    • contain neurotransmitters, that trigger changes in the target cells of the neuron
    • acetylcholine
  3. Synaptic Cleft
    the narrow space between the axon terminal and the muscle fiber into which ACh is released
  4. Motor end Plate
    is specialized region of the sarcolemma, who folded surface contains many receptors for ACh
  5. 3 phases of the muscle contraction process
    excitation phase, excitation-contraction coupling, contraction phase
  6. excitation phase
    When the neuron excites the muscle
  7. stages of contraction from the intramuscular junction
    • 1 an action potential arrives at the axon terminal
    • 2 Synaptic vesicles release acetylcholine into the synaptic cleft
    • 3 Acetylcholine binds to ligand-gated ion channels in the motor end plate
    • 4 Ion channels open and sodium ions enter the muscle fiber
    • 5 Entry of sodium ions depolarizes the sarcolemma locally, producing an end-plate potential
  8. end-plate potential
    This potential is simply a local depolarization in the area of the motor end plate
  9. acetylcholinesterase
    As soon as ACh is released from the synaptic vesicles, it is degraded and inactivated almost immediately by and enzyme in the synaptic cleft. For this reason the neuron must continue to fire action potentials and release new ACh in order to stimulate repeated end-plate potentials in the muscle fiber
  10. botox
    Block ACh from binding at the motor end plate
  11. excitation-contraction coupling
    In this phase, the end- plate potential leads to an action potential in the sarcolemma, which in turn triggers events that result in contraction
  12. steps of excitation-contraction coupling
    • 1 the end-plate potential stimulates an action potential
    • 2 The action potential is propagated down the T-tubules
  13. muscular system
    The skeletal muscles
  14. skeletal muscle
    • striated
    • long
    • multinucleated
  15. cardiac muscle
    • Striated
    • branched
    • one or two nuclei
    • have intercalated discs
    • involuntary
  16. smooth
    • Nonstriated
    • spindle shaped
    • involuntary
  17. Extensibility
    Most cells rupture when stretched but muscle cells can stretch up to 3 times their original length
  18. elasticity
    Muscle cells can return to their original shape
  19. Sarcoplasm
    contains cytosol and all of the organelles in the muscle cell
  20. composed of a phospholipid bilayer with multiple specialized integral and peripheral proteins
    Sarcolemma
  21. inside of the sarcoplasm are small cylindrical organelles  called _______ that help the muscle contract
    myofibrils
  22. how big is a myofibril
    1/100 of a human hair
  23. forms a web-like network around each myofibril
    sarcoplasmic reticulum
  24. Most abundant organelle in the sarcoplasm
    myofibril
  25. a muscle fiber is surrounded by the 
    equivalent to the plasma membrane on a cell
    Sarcolemma
  26. The Sarcolemma creates inward extensions into the muscle called
    T tubules
  27. Two enlarged portions of the SR on either side of the T tubules is known as
    Terminal Cisternae
  28. terminal cisternae and the T tubule together are known as
    Triad
  29. Surrounds each muscle fiber
    Endomysium
  30. a myofribril is composed of hundreds to thousands of protein bundles called ______
    myofilaments
  31. 3 types of proteins and their function
    • contractile- tension
    • Regulatory- when contraction takes place
    • Structural- hold myofilaments in their proper position (z discs)
  32. tropomyosin and tropinin are known as _____ proteins
    Regulatory
  33. actin is known as a __________ protein
    Contractile
  34. a structural protein that includes resisting excessive stretching and providing elasticity to the muscle fiber
    titin
  35. multiple skeletal muscle fibers together with the surrounding endomysium form a ____
    Fascicle
  36. Each fascicle is surrounded by the
    Perimysium
  37. bundles of fascicles together make up a
    Skeletal Muscle
  38. the skeletal muscle is surrounded by the
    epimysium
  39. which band contains only thin filament
    I band
  40. Which band contains only thick filament and some of the thin filament from overlap
    A band
  41. middle zone is called
    M line or H zone
  42. what band are the z disc located in
    The I band
  43. The functional unit of contraction where muscle tension is produced
    z disc to z disc
    Sarcomere
  44. the branch of physiology that studies electrical changes across plasma membranes
    electrophysiology
  45. Because the flow of ions across a gradient goes from potential to kinetic energy, we call the electrical gradient an
    electrical potential
  46. a difference in electrical ptential between two pints is called a
    voltage
  47. how much is a millivolt
    1/1000 of a volt
  48. the electrical potential across a plasma membrane
    membrane potential
  49. the electrical potential across the sarcolemma in a muscle fiber at rest is called the
    Resting membrane potential
  50. Why is the membrane considered to be polarized
    Because of the charge on either side of the membrane
  51. the most important active transport pump for Na and K is
    Na/K ATPase pump
  52. millions of these Na/K pumps work together to maintain concentration gradients that keep a resting potential, were do we find higher and lower concentration gradients
    • low potassium and high sodium in the ECF
    • High potassium and low sodium in the cytosol
  53. a quick temporary change in the membrane potential in a single region of the plasma membrane
    Action potential
  54. what are the two types of gated channels
    Ligand gated and voltage gated
  55. open in response to the presence of certain chemicals called ligands
    ligand gated channel
  56. open and close in response to changes in the membrane potential across the plasma membrane
    voltage gated channels
  57. When Na flows in, the membrane potential becomes _______
    • less negative
    • (depolarization
  58. when K leaves the cell the membrane potential becomes
    • More negative again
    • repolarization
  59. returning the sarcolemma to restion potential of -85 mv will caus_______________
    potassium ion channels to close
  60. action potentials do not stay in one place; rather, they are conducted, or ________
    Propogated
  61. remember that that the t tubules are attached to the sarcolemma so that when the action potential affects the sarcolemma it also travels down the
    T- tubules
  62. a myosin head bound to an actin molecule is known as a
    crossbridge
  63. what cocks the myosin head
    ATP Hydrolysis
  64. for the average contraction, how many times will the myosin head preform the powerstroke
    20-40
  65. What are the two components of muscle relaxation
    • ACh release stops and the remaining ACh in the synaptic cleft is broken down
    • the calcium ion concentration in the cytosol returns to its resting level
  66. a muscle that is unable to relax is said to be in a
    Spasm
  67. What are the three processes that regenerate ATP
    • reactions in the cytosol that immediately add a phosphate group to ADP
    • glycolytic catabolism
    • oxidative catabolism
  68. reaction in the cytosol that immediately add a phosphate group to ADP is known as
    Creatine Phosphate reaction
  69. What are the two potential sources of glucose for glycolysis
    glucose that enters the fiber from the bloodstream and a storage form of glucose called glycogen
  70. If oxygen is abundant ______ will enter the mitochondria for oxidative catabolism
    pyruvate
  71. If oxygen is not abundant, the pyruvate is converted into ____ molecules of the compound ______
    two, lactic acid
  72. about 20% of lactic acid is diffused into the bloodstream and converted to _____ in the liver
    glucose
  73. what pyruvate does not enter the bloodstream goes in to the mitochondria for
    Oxidative  or aerobic catablolism
  74. similar to hemoglobin
    the oxygen carrying protein in cytosol
    myoglobin
  75. the response of a muscle fiber to a single action potential in a motor neuron
  76. latent period
    The time it takes for an action potential to spread through the sarcolemma
  77. an interval of about 5 ms during which the muscle cannot respond to another stimulus
    Refractory period
  78. have refractory periods as long as their contraction
    Smooth and cardiac muscle
  79. When repeated stimulation of a muscle fiber by a motor neuron results in twitches with progressively greater tension this is known as
    Wave summation
  80. when the muscle fiber can only partially relax between contraction
    unfused tetanus
  81. when the tension remains constant at a maximal level
    fused Tetanus
  82. the optimal tension level depends on the __________________
    Length of the sarcomere prior to contraction
  83. the _________ of the sarcomere is the length of the muscle fiber at which the most cross-bridges can form
    optimal length
  84. Muscle fibers with high myosin ATPase activity are called
    Fast Twitch Fibers
  85. Muscle fibers with low myosin ATPase activity are called
    Slow twitch fibers
  86. two main classes of skeletal fibers
    Type I and Type II
  87. Type I =
    Type II =
    • Slow twitch
    • Fast twitch
  88. a single motor neuron along with the muscle fibers it innervates
    Motor Unit
  89. as greater force is needed, more motor units are activated. This is known as a phenomenon called
    Recruitment
  90. During recruitment ______ units are recruited first followed by _______ motor units if more force is needed
    slow, fast
  91. the involuntary activation of motor units that creates a small degree of tension is known as
    Muscle Tone
  92. muscle tone serves important functions such as
    Maintaining erect posture, stabilizing joints, generating heat and ensuring that the muscle is ready to respond if movement is initiated
  93. if the tone in a skeletal muscle is abnormally low, this is generally known as a condition called
    Hypotonia
  94. a muscle with abnormally high tone is called
    occurs during shivering
    hypertonia
  95. another way of saying that a muscle wil alter its structure to follow its function
    principle of myoplasticity
  96. These cells help repair injured skeletal muscle
    Satellite cells
  97. in response to physical inactivity, the diameter of the mucles fiber decreases due to loss of myofibrils
    atrophy
  98. During exercise, heat in the mody is generated and the body must dissipate this heat and return to pre-exercise temperature levels to maintain temperature homeostasis
    Heat Dissipation
  99. Propels materials through hollow organsof the digestive, urinary, and reproductive systems
    Peristalsis
  100. In smooth muscle cells, the actin filament are arranged obliquely in the sarcoplasm and are anchored to proteins called
    Dense bodies
  101. in smooth muscle cells there are more ______ filaments than _______fiaments
    Thin, thick
  102. in smooth muscle cells, thin filaments lack
    troponin
  103. 3 ways smooth muscle is different than skeletal muscle (Structurally)
    • Lacks motor end plates
    • Teh sarcoplasmic reticulum is much less extensive
    • T-tubules are absent
  104. Some smooth muscle cells are able to depolarize and contract spontaneously, these cells are known as
    Pacemaker cells
  105. in smooth muscle, calcium ions bind to a protein called
    Calmodulin
  106. smooth muscle can contract up to _____ of its length while skeletal muscle can contract up to _______
    • 80
    • 30-40
  107. during the _______  the muscle cell maintains tension while consuming very little ATP
    Found in Sphincter that must remain close
    latch state
  108. _______ allows the heart to contract as a unit by attaching it physically and electrically
    intercalated discs
  109. cardiac muscle is run by a small population of ______ for contraction
    Pacemaker cells
  110. what is the resting potential of a muscle fiber
    -85 mV
  111. is caused by depletion of key metabolites, inadequacy of oxygen delivery to muscle fibers, accumulation of certain metabolites, and environmental conditions
    Muscle fatigue
Author
Bnasty
ID
335573
Card Set
Human AP 4.1
Description
chapter 10
Updated