Muscle Contraction Mechanism
Jumat, 19 Oktober 2012
1 Komentar
When
muscle is in the rest condition or being relax, there will not be any
interaction between thick and thin myofilaments. This happens because the
active sites of both myofilaments are blocked by tropomyosin compound.
The
muscle contraction occur if the stimulation coming from motorist nervous system
releases transmitter substance (acetylcholine) that causes permeability change
in sarcolemma (muscle cell membrane ) The Na+ion ouside sarcolemma will flow
fast into cell and cause Na+ion will compound with troponine, so that the
active site of myofilament is freed from the tropomyosin blockage. The release
of tropomyosin causes interaction between actins and myosin. The myosin fiber
will drive action fiber, so that both fibers slide and become closer, and the
cell shortens or contracts. The I band and H zone disappear as the Z lines come
closer together.
As
long as there is nervous stimulation, the concentration of 
ion becomes high, and this condition will
occur continuously. In turn, If the stimulation stops, the concentration of ion becomes low, so that tropomyosin will move back to the active site
of myofilament to block it.
ion becomes high, and this condition will
occur continuously. In turn, If the stimulation stops, the concentration of ion becomes low, so that tropomyosin will move back to the active site
of myofilament to block it.
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