Fig 10 11 just read over this and get a general idea

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Unformatted text preview: iculum. Nerve signals carried DEEPLY into muscle fiber by T-Tubules, causes calcium ion release from Sarcoplasmic reticulum. Fig. 10-11 JUST READ OVER THIS AND GET A GENERAL IDEA. Ca2+ ions bind to troponin, moving tropomyosin to expose the sites on actin that interact with the myosin heads. Myosins bind ATP and pivot, pulling actin filament along thick filament. ATP breaks down and myosins detach, then attach again to other G-actins farther along thin filament. Repeating this cyclically causes contraction. When the muscle is relaxed (top), the I bands and sarcomeres themselves are at their widest. SARCOMERE SHORTENS WHEN FILAMENTS SLIDE PAST EACH OTHER -- BUT LENGTH DOESNT CHANGE! TITIN - LARGEST PROTEIN IN CELLS -- AUTOMATICALLY PULLS FILAMENTS BACK TO THEIR STARTING POSITION DURING RELAXATION? In a partially contracted muscle, the I band and sarcomere are shorter (narrower). In a fully contracted muscle, the sarcomere is at its shortest and the I bands disappear. Fig. 10-12 Through these changes, the actual length of the thick & thin fila...
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