inside muscle fiber, same length fiber encircled by T tubules composed of myofilment
filaments 2 type of
thin filament-protein actin, thick filaments protein myosin
responsible for muscle contraction/ anchored in inner surface of sarcolemma outer surface of sarcolemma attached to collagen fibers of tendon
sarcoplasmic reticulum (SR)
similar to smooth ER of other cells, tubular network , surr each myofibril
form terminal cisternae at either side of T tubule/ 2 terminal cisternat + 1 T tubule = Triad
Ca++ actively transported from sarcoplasm
relased into sarcoplasm contraction begins
smallest function unit , capable of contraction
I band in sarcomeres
light-actin only thin filament extend to A band
boundary between sarcomeres, interconnect thin filaments in sarcomere
forms core to thick filaments @ Z line functions to restoration of fiber length after contraction
dark myosin 3 subdivisons
3 subdivions of A bands
M line, H band zone of overlap
center of each thick filament interconnected by proteins
either side of M line-only thick filament
zone of Overlap
thin filaments between thick filaments, darkest
Ca+ expos to active sites, formation of cross-bridges, pivoting of myosin heads, etachment of cross-bridges, reactivation of myosin
sliding filament theory
thin filaments slide alongside thick filaments then muscle fiber shorters
excitation contraction coupling
start of action potential int the sarcolemma snd the start of a muscle contraction called
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