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Skeletal Muscle Parts

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epimysium
connective tissue covering entire muscle
fascia
covers outside of epimysium
muscle fasciculi
visible bundles composed of muscle fibers that make up the whole muscle
perimysium
connective tissue that covers muscle fasciculi
muscle fiber
make up the fasciculi; also known as a muscle cell
endomysium
connective tissue layer that covers muscle fibers
sarcoplasm
cytoplasm of the muscle fiber
myofibril
threadlike structure composed of myofilaments that extends the length of the muscle fiber
actin myofilaments
thin myofilament that looks like a string of pearls
troponin
provides calcium attachment sites; part of actin myofilament
tropomyosin
exposes calcium attachment sites; part of actin myofilament
myosin myofilament
thick myofilament; looks like golf clubs
sarcomeres
basic structural and functional unit of skeletal muscle; smallest part that can contract on its own
Z line
beginning and end of a sarcomere
I band
light zone; has actin only; shortens during contraction
A band
dark zone; has both actin and myosin overlapping
H zone
center of sarcomere; space between actin; disappears during contraction; second light zone
M line
middle of sarcomere
sarcolemma
cell membrane of muscle fiber
T tubules
connects sarcoplasmic reticulum
sarcoplasmic reticulum
specialized smooth ER; high calcium concentration