Muscle Contraction

Muscle Contraction - i . This, in turn, causes a change in...

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Muscle Contraction Muscle contraction events describing the sliding-filament concept are listed as follows. •   ATP binds to a myosin head and forms ADP + P i . When ATP binds to a myosin head, it is  converted to ADP and P i , which remain attached to the myosin head.  •   Ca 2+  exposes the binding sites on the actin filaments. Ca 2+  binds to the troponin molecule,  causing tropomyosin to expose positions on the actin filament for the attachment of myosin heads.  •   When attachment sites on the actin are exposed, the myosin heads bind to actin to form cross  bridges. •   ADP and P i  are released, and a sliding motion of actin results. The attachment of cross bridges  between myosin and actin causes the release of ADP and P
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Unformatted text preview: i . This, in turn, causes a change in the shape of the myosin head, which generates a sliding movement of the actin toward the center of the sacromere. This pulls the two Z discs together, effectively contracting the muscle fiber to produce a power stroke. ATP causes the cross bridges to unbind. When a new ATP molecule attaches to the myosin head, the cross bridge between the actin and myosin breaks, returning the myosin head to its unattached position. Without the addition of a new ATP molecule, the cross bridges remain attached to the actin filaments. This is why corpses become stiff with rigor mortis (new ATP molecules are unavailable)....
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This note was uploaded on 11/10/2011 for the course PT 101 taught by Professor Staff during the Spring '10 term at Texas State.

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