BILD2Lec7Figs

BILD2Lec7Figs - Fig. 50-25: The structure of skeletal...

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Unformatted text preview: Fig. 50-25: The structure of skeletal muscle Muscle Bundle of muscle fibers Single muscle fiber (cell) Plasma membrane Myofibril Light band Dark band Z line Sarcomere TEM 0.5 m I band A band I band M line Thick filaments (myosin) Thin filaments (actin) H zone Sarcomere Z line Z line Nuclei Z Relaxed muscle M Z Fully contracted muscle Contracting muscle Sarcomere 0.5 m Contracted Sarcomere Fig. 50-26: The sliding-filament model of muscle contraction (a) Relaxed muscle fiber. In a relaxed muscle fiber, the I bandsand H zone are relatively wide. (b) Contracting muscle fiber. During contraction, the thick and thin filaments slide past each other, reducing the width of the I bands and H zone and shortening the sarcomere. (c) Fully contracted muscle fiber. In a fully contracted muscle fiber, the sarcomere is shorter still. The thin filaments overlap, eliminating the H zone. The I bands disappear as the ends of the thick filaments contact the Z lines. Fig. 50-27: Myosin-actin interactions underlying muscle fiber contractionFig....
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This note was uploaded on 01/24/2010 for the course BICD BILD2 taught by Professor Berg during the Spring '10 term at UCSD.

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BILD2Lec7Figs - Fig. 50-25: The structure of skeletal...

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