IMG - t I rt-t l Seconci slimulus Sacond c0ntracli0 i lwave...

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Lt3u20tt The Muscle Twitch and Contractile Behavior
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U3u20lt 3. Muscle Twitch Relaxation 10-100ms reentry of Ca into SR no more force ) tension falls to zero if muscle shortened it now returns to its initial length
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1t3u20ll Fast and Slow Twitches A comparison of the rates with which maximum tension is developed in three muscles: a) fast twitch extraocular_b) gastrocnenius museles and c) slow twitch soleus muscle Graded Responses
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y31/2011 Wave (Temporal) Summation If two identical nerve impulses are delivered one after the other, the second twitch will be stronger because it was induced before the muscle relaxed from the first contraction Since the muscle is already partially contracted, the second contraction causes more shortening ) contraction force increases . The two contractions are summed up 20A The second contraction rides on the shoulder of the first o o Firsl contraclion 1: (rwilch)
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Unformatted text preview: : t, I rt ,-t\ l, ,.,: Seconci ,, slimulus Sacond c0ntracli0* i lwave sumrratronl ! l ... oi I lft ] l-Frrst st,nrulus | :, l-:--r------ | 1. . 1. 10 20 30 40 50 60 70 Time in milliseconds (msec) + (a) Wave summatEn Myograms showing effect of different frequencies of stimulation 0r23 Time in seconds (sec) + (b)lncomplele {c)Compleie teiarus letanus 4 t/3U2071 If the second stimulus arrives before repolarization is complete, there will tre no summation i- I r:t'tr r't.;. ! {Lit;:f i', I i. .-, . .-:i a. :. . Usually the muscle is stimulated at avery fast rate so the relaxation time between twitches decreases and summation gets greater Eventually, relaxation disappears and the contractions fuse into a smooth, sustained contraction called TETANUS To achieve this motor impulses are delivered in raptd successlon...
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IMG - t I rt-t l Seconci slimulus Sacond c0ntracli0 i lwave...

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