HOOK Muscle is only biological cell/tissue that can cause rapid, large-scale movement Role of filamentous proteins understood as great and early breakthrough in cell/molecular biology—lots of protein available, (like Hemoglobin). Sliding Filament Model of Muscle Contraction.
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Larry M. Frolich, Ph.D.
April 15, 2010
I normally cover neurons and muscle together as part of unit on movement—see website
Sequence of events Motor Neuron to Muscle contraction at cellular level
(from the Brain Top to Bottom) [link]
How does the actin-myosin complex (sarcomere) shorten and contract the muscle?
Put the sliding filaments back into a whole muscle…
Tropomyosin and troponin create binding site on actin filament
Presence of Ca++ exposes binding site
“Cocked” cross-bridge on myosin (uses ATP) then attaches to binding site and pulls or “rows” actin filament
Cross-bridge linkage is broken and re-cocks to link with next binding site
Why muscle has peak force at certain length: (ideal actin-myosin overlap for cross-bridge formation)—BUCKET DEMO
More muscle cells means more muscle force: (more cross-bridge formation)—EMG, Isolated muscle online lab
Concentric/isometric/eccentric contraction: Cross-bridges continue to form and “reach” even if opposing force is greater