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21 Cards in this Set
- Front
- Back
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Specialized cell membrane of muscle
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Sarcolemma
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Cytoplasm of muscle is called
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Sarcoplasm
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Why is striated muscle called Thin filament regulated
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Activation is via Ca binding to troponin which along with tropomyosin is one of regulatory proteins found on thin filament
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Name 3 fibers types of skeletal muscle
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Type I - slow twitch, oxidative, red
Type IIb- fast twitch, glycolytic, white Type IIa- fast twitch, nixed oxidative and glycolytic, white |
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Difference between cardiac muscle and striated muscle
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Cardiac muscle is only in heart
-Has gap junctions -highest sustainable metabolic rate -Auto rhythmic |
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Difference between striated and smooth
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No striations in smooth muscle
-Thick filament regulated, activation through phosphorylation of muscle proteins found in thick filaments |
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Describe skeletal muscle fibers
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-Multinucleated
-Electrically isolated -Packed with contractile proteins |
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Thick filament contains
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Myosin
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Thin filament contains
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Actin
Tropomyosin Troponin |
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I band
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Isotropic - allows polarized light to pass through
-primarily thin filaments -runs from A to A band |
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A band
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-primarily thick filaments (can contain overlapping thin and intermediate filaments)
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H zone
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THICK filaments only
Can be part of or include whole A band |
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Z line
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Structure demarcating separation of sarcomeres
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M line
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Central line of sarcomere
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What happens in sarcomere when muscle is activated
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-Sarcomeres shorten, Z lines get closer
-A band remains CONSTANT -I band and H zone shorten -Myofilament length remains constant |
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Phase I of muscle contraction
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Transient increase in Ca relieves natural block by troponin and tropomyosin of actin/myosin interaction - increases ATPase activity of myosin by 1000 times
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Phase II of muscle contraction
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Power stroke, S1 goes from 90 degrees to 45 - primary force generation step
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Phase III
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Myosin detaches from actin upon release of ADP, to which it has higher affinity
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Describe what happens in rigor mortis
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Muscle relaxes when ADP replaces actin in myosin. When ATP is not available, crossbridge will remain attached in high stiffness/low force position causing rigor mortis
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T tubules
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central to excitation contraction coupling
Invaginations of sarcolemma near A-I band |
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Feet of t tubules are
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voltage sensing elements, lead to release of Ca
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