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img076 - 3K FOF‘CQ S‘gflafio o(ringed-5 cq)‘#—...

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Unformatted text preview: 3K FOF‘CQ S‘gflafio o (ringed-5 cq)‘. #— c€ active ,— firm eudn {ocL‘vr'dr muscLQ‘t'beF can ”‘6qu C mjswbn‘clfiez) -' 5r 8' s c w t qté c b6 0/). QC 11% i441? 42:41 — . 0+ mm, M” m: m“ Go to the next screen: The forcegenmfionin a ,_ 53:3“. T1?” muscle depends of two factors: 1) the force each individual “4'9“" .m"'“°"“'"'““""'°"m°""°"“”‘ muscle fibereangenerate—this depends on thenumber of .- 'GL, U‘ 0M“ aim-m- rum-din ham-aim active cross-bridges; and 2) the number of fibers that are 0U W 01—:— hummus-mammal,“ . . . :u mum. an. contracting. The number of active cross-bridges depends 0'“- ”Mden..." W, on frequency of stimulation, fiber diameter and changes in 3:“ . memwmm m fiber length. We’ve already discussed the fiber length ' m... m. m m.“ by m. mm a mum issue. Now we will discuss fi'equency stimulation and fiber mew... dimer. p m m } mm In lieu length LL“: 8 flm' "« .3 . "Jr; mi: 0"“ m” ”3:" Go to the next screen: Mawitches are m w‘“'"""°" w .. . m H... m. M... d a. reproducible only if the muscle is stimulated at a runs-non pom 0' in. am mum. We“ n: m. m tau-a. mm __ sgpmted in time. At higher frequencies the rate 0 :5: ' : calcium release from the SR into the cytosol excwds the rm rate of calcium active transport from the cytosol back to —- the SR, resulting in an increase in the peak tension. The """"" mm more calcium in the cytosol, the more calcium bound to 3 troponin, which move the tropomyosin to expose more i myosin-binding sites on actin. The more myosin—binding -- sites exposed the more crossbridges can participate in EE ' " «'11; W -- crossbridge cycling and the greater the tension development. G0 to the next screen: Here, the time interval has been lengthened to 70 ms. Note that there is still summation but the first twitch has started to retum back to testing level. G0 to the next screen: Here the time interval between twitches has been lengthened to 90 ms. Note that the tension generated is almost the same between the two twitches. The second twitch is slightly higher bemuse the first twitch did not completely return to zero. The second twitch will always be higher than the first if it arrives before the first twitch has . mew-dad WWW: ‘1 G0 to the next screen: As the stimulation fiequency “mm OW shulus Mil-mt elou W . . . increases, muscles move from tWitch contractions, to 5 treppe, to summation and finally to tetanus. MAMA” , F ‘ \wlxdx ~v fi Wfi ‘73me W “‘7 :qcéf’tVUZ/H —9 “WW ---o °”3'-” °:8 Wet/S W Page 5 of 8 ...
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