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25 Cards in this Set
- Front
- Back
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3 levels of organization in skeletal muscle?
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epimysium, perimysium, endomysium
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what is the role of connective tissue in muscle function? (4)
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harness for muscle tissue, resist passive stretching to minimize damage, enables muscle to regain shape, transmits contractile force laterally
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what is the role of SL in muscle function?
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selective to ions, solutes and substrates therefore creates membrane potential
maintain pH propagates action potential |
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what is the role of satellite cells in muscle function?
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important for growth, development and adaptations and recovery from injury
have instructions for protein synthesis |
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what are the main features of a sarcomere?
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Aband - dark, midportion, thick and think filametn overlap
Iband - light, outer ends, less tissue density Hzone - central region of Aband, no filament overlap Mline - bisects Hzone and keeps sarcomere in correct spatial orientation Zline - at end of sarcomere |
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what are the roles of regulatory proteins?
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myosin, actin - contractile, tropomyosin, troponin - regulatory
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what are the structural proteins?
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myosin binding protein C - links titin with myosin
titin - centers myosin in sarcomere myomesin - keep thick and thin filaments in correct spatial orientation alpha actinin - links z disks |
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what are the troponin proteins and what do they do?
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TnT - binds TM
TnI - blocks actin binding site TnC - binds calcium to change conformation of tropomyosin |
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what is meant by hybrid fibers in muscle?what is the functional consequence of this?
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many fibers within limb muscles express more than one type of MHC
it provides the fibers with a rapid capability to remodel its structural-functional properties |
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what are the main structural elements of thick filament?
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50 molecules of Tn and TM
globlular has a binding site that atteches myosin corss bridges when exposed |
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what happens at low intracellular concentrations of Calcium?
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Tm blocks binding site of actin there for myosin cross bridges cannot attach
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what happens at higher intracellular calcium concentrations?
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additional calcium binds to troponin and TnC binds an additional two calcium molecules at a separate regulatory site to undergo a conformational change and expose the actin binding site to myosin crossbridges
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what are the main even of the sliding filament theory? (4)
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myosin cross bridges attach
working stroke - myosin head pictos and slides actin filament and ADP and Pi are released new ATP head attaches to the myosin head, the cross bridge detaches ATP slits into ADP and Pi which cocks the myosin head |
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what are the 3 ways to measure capillarity in skeletal muscle?
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number of adjacent capillaries/fiber
capillaries/cross section - density capillary to muscle fiber ration - best estimate |
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what effect does training have on capillarity
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can increase by 5-20% within 12 weeks of endurance training
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what are the main point relating to architectural factors that affect muscle function and how?
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the more sarcomeres arranged in series the greater the velocity
the more sarcomeres arrange in parallel, the greater the force pinnation - as angle increases, force is reduced as long as angle is less than 30 degrees the force lost is compensated for by the parallel packing |
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what are the different types of muscle contraction?
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isometric/fixed end - no change in length
concentric/mimoetric/isotonic - shortening because muscle force exceeds load eccentric/pliometric - lengthening because load exceeds muscle force |
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what happens with unfused/fused tetanus
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low frequencies
higher frequency, frequency of stimulation reached, full smmation, 3-5x greater than twitch tensino |
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what are the main determinants of twitch properties?
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MHC and SR - faster relaxation therefore need greater Hz to fully activate - fast twitch
twitch tension, time to peak tension, 1/2 relaxation time |
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what mechanisms are used to control muscle recruitment?
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modulation of frequency - rate coding
slow muscle produces a greater relative amount of force at any given frequency |
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what factors affects power output of muscle?
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Hz , recruitment , fiber position relative to its optimal length,
muscle fiber length, myosin ATPase |
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excitation-contractoin coupling?
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action potential generated is propagated along the sarcolemma and down the t-tubules
action potential triggers calcium release from cistamae of SR calcium ions bind to troponin causing conformational change and removes blocking action of Tm contratcion - myosin cross bridges alternately attach to actin and detach - ATP is released removal of calcium by active transport into the SR after action potential ends tropomyosin blockage restored |
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what are the main features of different motor unit types?
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histochemical stains
type 1 - slow oxidative - pink-red type 2a - FOG, red type 2b - FG, white all differentiated by combinations of MHC or MLC - hybrid nature slow fibers require less calcium to activate fast glycolytic undergo most significant adaptations with endurance training |
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what underlying mechanisms help explain strength training mechanisms?
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strength, neural adaptations, hypertrophy
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what are the most importatn determinants of muscle adaptation?
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energy intake hormones, recruitment load
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