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Muscle Physiology
Muscle Physiolgoy
114
Anatomy
Undergraduate 2
06/08/2009

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Cards

Term
1. Can a motor neuron innervate more than one muscle fiber?
Definition
yes
Term
2. What is the term for the highly excitable region of a muscle fiber where a neuromuscular junction is located?
Definition
motor end plate
Term
3. What muscle fiber characteristics would you see at the motor end plate?
Definition
hightly folded sarcolemma and lots of mitochondria
Term
4. What neurotransmitter does the motor neuron release at a neuromuscular junction?
Definition
acetylcholine
Term
5. Name a drug that inhibits the release of acetylcholine from motor neurons causing muscles to be paralyzed.
Definition
Botox
Term
6. What does acetylcholine bind to on the motor end plate?
Definition
acetylcholine receptors
Term
7. What happens when the acetylcholine receptors open (what flows where)?
Definition
sodium flows into the muscle cell
Term
8. Where will action potentials produced at the motor end plate travel?
Definition
along sarcolemma and down t-tubules
Term
9. Action potentials that travel down the t-tubules will cause what to open on the terminal cisterna of the sarcoplasmic reticulum?
Definition
calcium channels
Term
10. What will the calcium released from the sarcoplasmic reticulum bind to?
Definition
troponin
Term
11. The conformational change in troponin due to calcium will cause what to happen?
Definition
a conformational change in tropomyocin that will reveal active sites on actin
Term
12. What are the active sites on actin for?
Definition
where myocin heads bind to actin
Term
13. What is attached to the myocin head when it is in a high energy state?
Definition
ADP + phosphate
Term
14. What is released from the myocin head BEFORE it attaches to the active site on actin?
Definition
phosphate
Term
15. What is released from the myocin head AFTER it attaches to the active site on actin?
Definition
ADP
Term
16. What is the term for the ratchet like movement of the myocin head that causes the thin filaments to slide over the thick filaments?
Definition
power stroke
Term
17. During a contraction, do sarcomeres shorten or lengthen?
Definition
shorten
Term
18. What causes the myocin head to release from actin?
Definition
ATP binding to myocin
Term
19. After muscle contraction, what happens to the calcium?
Definition
it is actively pumped back into the sarcoplasmic reticulum
Term
20. What happens to the acetylcholine left in the synapse of the neuromuscular junction?
Definition
it is broken down by acetylcholinesterase into acetic acid + choline
Term
21. What parts of a sarcomere shorten during contraction?
Definition
the whole sarcomere, the I band, and the H zone
Term
22. What parts of a sarcomere remain the same during contraction?
Definition
the A band and the myofilaments themselves
Term
23. What sarcomere length allows for the maximum number of cross-bridges and generates the greatest amount of tension?
Definition
2.0 - 2.25 um
Term
24. What sarcomere length limits the number of cross-bridges that can be formed (less actin/myosin overlap)?
Definition
greater than 2.25 um
Term
25. What happens to the tension produced if the sarcomere length is greater than 2.25 um?
Definition
tension is reduced
Term
26. What sarcomere length limits the distance for the thin filaments to slide?
Definition
less than 2.0 um
Term
27. What happens to the tension produced if the sarcomere length is less than 2.0 um?
Definition
the tension generated is reduced
Term
28. What is the term for a single contraction of a single muscle fiber in response to a single stimulus?
Definition
a twitch
Term
29. During a twitch, what is the term for the time between stimulus and beginning of contraction?
Definition
lab phase
Term
30. During a twitch, what is the term for the time during which contraction occurs?
Definition
contraction phase
Term
31. During a twitch, what is the term for the time during which relaxation occurs?
Definition
relaxation phase
Term
32. Does the magnitude of a single MUSCLE FIBER twitch change if you increase the stimulus strength?
Definition
no
Term
33. During a twitch, what is going on during the lag phase?
Definition
time for the calcium to attach to troponin, troponin to change shape, tropomyocin to change shape, etc.
Term
34. What are two types of summation for successive MUSCLE FIBER twitches?
Definition
multiple-wave summation and temporal summation
Term
35. During summation, what happens to the lag phase and relaxation phase?
Definition
they shorten and begin to disappear
Term
36. During summation, what happens to the contraction phase?
Definition
it lengthens
Term
37. During summation, what happens to the tension generated?
Definition
it increases
Term
38. What is the term for a sustained contraction due to maximal frequency of stimuli?
Definition
tetanus
Term
39. During tetanus, what happens to the lag phase and relaxation phase?
Definition
they disappear
Term
40. During tetanus, what happens to the contraction phase?
Definition
it is constant
Term
41. During tetanus, how much tension is generated?
Definition
the greatest amount of tension (at its peak)
Term
42. During a twitch of a MUSCLE FIBER, what genertes tension?
Definition
sarcomere length
Term
43. During a twitch of a WHOLE MUSCLE, what genertes tension?
Definition
motor units
Term
44. For the muscles in your fingers, are there a few or a lot of muscle fibers per motor unit?
Definition
a few (allows for finer movements)
Term
45. For the muscles in your legs and back, are there a few or a lot of muscle fibers per motor unit?
Definition
a lot (for larger gross movements)
Term
46. What are two types of summation for WHOLE MUSCLE twitches?
Definition
multiple motor unit summation and spatial summation
Term
47. What does a larger stimulus do during multiple motor unit summation?
Definition
more motor units are recruited
Term
48. What happens to the tension generated during multiple motor unit summation?
Definition
tension increases
Term
49. If you have stimulated the maximum number of motor units for a given muscle and get x amount of tension produced, what will happen if you increase the stimulus?
Definition
you will still produce the same amount of tension because you have already reached the maximum amount of motor units
Term
50. What type of muscle contraction will change muscle length?
Definition
isotonic contraction
Term
51. What type of muscle contraction will not change muscle length?
Definition
isometric contraction
Term
52. What is the term for the isotonic contraction where muscle tension exceeds resistance and the muscle shortens?
Definition
concentric contraction
Term
53. What is the term for the isotonic contraction where resistance exceeds muscle tension and the muscle lengthens?
Definition
eccentric contraction
Term
54. If I am pushing against a wall, what type of muscle contraction is occuring?
Definition
an isometric contraction
Term
55. What is the state of partial muscle contraction due to nerves continually stimulating motor units?
Definition
muscle tone
Term
56. What happens to muscle tone with upper motor neuron damage?
Definition
tone is increased
Term
57. What happens to muscle tone with lower motor neuron damage?
Definition
tone is decreased
Term
58. What is the term for the involuntary and forcible contracture of muscle with failure to relax?
Definition
muscle cramp
Term
59. What are three common causes for muscle cramps?
Definition
fatigue / low EXTRACELLULAR calcium / dehydration
Term
60. What is the state of constant muscle rigidity that occurs several hours after death?
Definition
rigor mortis
Term
61. Rigor mortis occurs because of a complete depletion of ATP - what does this not allow?
Definition
does not allow the myosin heads to release from actin
Term
62. What is the immediate source of energy for a muscle contraction (provides only few seconds of energy)
Definition
ATP
Term
63. What are four other sources of energy for muscle contraction?
Definition
phosphocreatine, glycogen (glucose), fat (fatty acids & glycerol), and protein (amino acids)
Term
64. What type of energy is preferentially utilized during low to moderate intensity exercise?
Definition
fat (fatty acids/glycerol)
Term
65. What type of energy is preferentially utilized during moderate to high intensity exercise?
Definition
glycogen (glucose)
Term
66. What type of energy is utilized when glycogen and fats are depleted?
Definition
protein (amino acids)
Term
67. What process is a direct phosphorylation of ATP to yield 10 to 15 seconds of energy?
Definition
phosphogen system
Term
68. What process is a rapid production of ATP, does not require oxygen, and provides about 90 seconds of energy?
Definition
anaerobic metabolism
Term
69. What process occurs during prolonged activity and yields 32 ATP per glucose molecule?
Definition
areobic metabolism
Term
70. What is the sole source of energy used in anaerobic metabolism and what is this process called?
Definition
glucose / glycolysis
Term
71. What is produced as a waste product of glycolysis?
Definition
lactic acid
Term
72. What can be used as a source of energy in aerobic metabolism?
Definition
glucose, fatty acids, or amino acids
Term
73. What type of muscle fatigue may be linked to interleukin 6 that signals the brain to feel tired as a defense mechanism to conserve energy?
Definition
psychological fatigue
Term
74. What type of fatigue is due to a depletion of energy sources and an inefficiency to deliver oxygen?
Definition
muscular fatigue
Term
75. What three things are accumulated (and where) during muscular fatigue?
Definition
potassium (outside muscle fiber), phosphate (inside muscle fiber), and lactic acid (due to anaerobic metabolism)
Term
76. What type of fatigue is due to defective acetylcholine receptors or a decreased amount of acetylcholine released at the neuromuscular junction?
Definition
synaptic fatigue
Term
77. What is an example of an autoimmune destruction of acetylcholine receptors?
Definition
myasthenia gravis
Term
78. What is an example of an autoimmune destruction of pre-synaptic calcium channels?
Definition
Lambert-Eaton myasthenia syndrome
Term
79. What type of muscle fiber has a high respiratory capacity, high concentration of mitochondria, and a high concentration of myoglobin?
Definition
red, slow twitch fibers
Term
80. What type of muscle fiber has a high concentration of glycogen and a very low concentration of myoglobin?
Definition
white, fast twitch fibers
Term
81. What type of muscle fibers are slow oxidative fibers?
Definition
red, slow twitch fibers
Term
82. What type of muscle fibers are fast glycolytic fibers?
Definition
white, fast twitch fibers
Term
83. What type of muscle fibers are suited for endurance and contract slowly (slow myosin)?
Definition
red, slow twitch fibers
Term
84. What type of muscle fibers are suited for power movements and contract rapidly (fast myosin)?
Definition
white, fast twitch fibers
Term
85. What does slow and fast myosin mean?
Definition
slow - they hydrolyze ATP slowly / fast - they hydrolyze ATP fast (time it takes to start a new cross-bridge)
Term
86. What type of muscle fiber is a type I fiber?
Definition
red, slow twitch fiber
Term
87. What type of muscle fiber is a type IIb or type IIx fiber?
Definition
white, fast twitch fiber
Term
88. What type of muscle fiber is a fast twitch fiber and fatigue resistant?
Definition
intermediate fibers
Term
89. What type of muscle fiber is a fast oxidative-glycolytic fiber?
Definition
intermediate fibers
Term
90. What type of muscle fiber is type IIa or type III fibers?
Definition
intermediate fibers
Term
91. How do muscle cells grow?
Definition
by hypertrophy (enlargement) not hyperplasia (cell division)
Term
92. What is the protein that prevents hyperplasia in muscle cells?
Definition
myostatin
Term
93. What type of muscle lines the walls of internal organs and is involuntary?
Definition
smooth muscle
Term
94. What type of smooth muscle arrangement is sheets of spindle shaped cells that function together?
Definition
single-unit/visceral smooth muscle
Term
95. What type of smooth muscle arrangement is less organized and cells function independently of one another?
Definition
multiunit smooth muscle
Term
96. Where would you find single-unit smooth muscle?
Definition
walls of digestive tract, ureters, and uterus
Term
97. Where would you find multiunit smooth muscle?
Definition
arector pili muscle, in the iris, and walls of some blood vessels
Term
98. In smooth muscle, how are myofibrils organized (striated or not)?
Definition
organized randomly (not striated)
Term
99. In smooth muscle, what anchors actin to the sarcolemma?
Definition
dense areas
Term
100. In smooth muscle, what anchors actin to the sarcoplasm?
Definition
dense bodies
Term
101. What two things are lacking in smooth muscle?
Definition
troponin and t-tubules
Term
102. What is the calcium binding protein in smooth muscle (instead of troponin)?
Definition
calmodulin
Term
103. During excitation of smooth muscle, where does most of the calcium come from (remember - in skeletal from SR)?
Definition
mostly from extracellular stores (little from SR)
Term
104. In smooth muscle, what is activated once the calcium binds to calmodulin?
Definition
myosin kinase (it phosphorylates myosin head to put it in active state)
Term
105. In smooth muscle, the calcium-colmodulin complex does not cause the conformational change in tropomyosin (like troponin), what protein on actin actually does this?
Definition
caldesmon
Term
106. In smooth muscle, are contraction slow or fast, and why?
Definition
slow because the enzymes involved in cross-bridging are slow
Term
107. In smooth muscle, once the calcium is pumped out of the cell, what will the low concentration of calcium activate that will dephoshporylate the myosin head and cause relaxation?
Definition
myosin phosphatase (in skeletal - ATP)
Term
108. Can smooth muscle contractions be graded and sustained?
Definition
yes, can be graded (remember - not skeletal) and sustained
Term
109. What is the term for the sustained contraction of smooth muscle?
Definition
latch state
Term
110. Is cardiac muscle voluntary/involuntary, and striated/nonstriated?
Definition
involuntary and striated
Term
111. In skeletal muscle, the t-tubules are located between the A-band and the I-band, where are the t-tubules located in cardiac muscle?
Definition
at Z lines
Term
112. In skeletal muscle, the t-tubules formed triads with the terminal cisterna, what is formed with the t-tubules in cardiac muscle?
Definition
diads
Term
113. In cardiac muscle, stimulation of the sarcolemma will cause what _____ , that will in turn stimulate the release of calcium from the SR?
Definition
the influx of calcium into the sarcoplasm (calcium-induced calcium release)
Term
114. What is located between cardiac muscle cells that allow these cells to contract at the same time and help them form a syncitium?
Definition
intercalated discs
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