The areas of the a bands contain the heavier thick

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Unformatted text preview: f each thin myofilament is attached to the α-actinin in the Z line within the light areas called the I bands. The areas of the A bands contain the heavier thick filaments as well as thin filaments and are therefore denser and darker staining. Thin myofilaments are F-actin, with Ca2+-binding troponin and tropomyosin. The thick filaments are bundles of myosin. The end of each myosin contacts F-actin in the thin filaments. These interactions cause the filaments to slide past each other, shortening the sarcomeres (next 2 slides.) DIMERS. Interaction b/w THIN and THICK filaments (actin & myosin) slide against each other, thus shortening and causing a CONTRACTION. Sarcomere? Contractile region of muscle fiber.. Fig. 10-9 Fig. 10-11 Surface of muscle fiber (sarcolemma) has DEEP INVAGINATIONS which protrude down to the center of the fiber -surround all the fibrils in there!! These invaginations called T-TUBULES. T tubules are invaginations of the sarcolemma which coordinate Ca2+ release throughout the sarcoplasmic ret...
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