Lecture 13 – Muscle Physiology I

The sr has lateral sacs that lie up against and

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The SR has lateral sacs that lie up against and communicate with the T-tubule There are proteins that do this  communication Surrounding each sucle cell is a specific arrangement of t tubules and SR Functional Contractile Unit  In myofibril In the sarcomere, gets sorter when muscles contract M-line myosin molecules attach there Zones Used now as references Sarcomeres are the function units Made up of a bunch of bands A band – mostly thinck filaments,s protiions of thin filaments that overlap on both ends  of thick filaments H –zone – lighter area in the middle of the A band where thin filaments do not reach M – line – extends vertically down the middle of A band within the center of the H zone Z-line is connected to myosin molecule by a giant protein Avt as a spring and allow muscle to have elastic recoil When it shortens it puts tension on the molecule The contraction is over and the relazxation of this protein allows it to come back via  recoil Nebulin helps hold the actin g-actin and f-actin Thick filaments are mostly myosin
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Titin Ginaty elastic proteins Largest protein in the body Extends in both direction for M line along the length of the thick filament to Z lines at  opposite ends of the sarcomere Roles of Titin Along with M-line protieins helps stabilize position of thick filaments in relation to thin  filaments Greatly augments the muscle’s elasticity by acting as a spring Regulatory st of proteins – troponin and tropomyosin, and nebulin (aligning proteins)
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