Motor mechanisms
Keywords (reading p. 1014-1020)
Structure of skeletal muscle
Features of muscle cells
Sarcomere
PPT Slide
Sliding-filament model of muscle contraction
Thick and thin filaments slide past each other
At maximal contraction, there is no space at end of thick filament, thin filaments overlap
Molecular basis for movement of filaments against each other
ATP bound, head retracted and unattached
Hydrolysis of ATP cocks head
Myosin head attaches to actin filament
Release of ADP + Pi causes a further conformational change pushing against the actin filament
Binding of ATP to myosin head causes dissociation from actin filament
Cycle repeats and sarcomere shortens
Control of muscle contraction by Ca++
At rest, myosin cannot bind because sites are covered by tropomyosin
During muscle contraction Ca++ levels rise. Ca++ binds to troponin which then pulls tropomyosin way from the binding sites
What triggers the Ca++ rise that induces muscle contraction?
[Ca++] regulated by the sarcoplasmic reticulum
Structure of the sarcoplasmic reticulum
Sequence of events leading to muscle contraction
Characteristics of other muscle types:
Email: rlee@mail.wsu.edu
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