Skeletal Muscle Fibers Flashcards
A sheath of fibrous elastic tissue that surrounds an entire muscle
Epimysium
A sheet of connective tissue surrounding bundles of muscle fibers 
Perimysium
A layer of areolar connective tissue that ensheaths individual muscle fibers
Endomysium
Largest to smallest skeletal muscle fiber structure 
Muscle belly, epimysium, perimysium, endomysium, muscle fiber (cell)
A bundle of muscle fibers
Fascicles
Beneath the endomysium, muscle fibers are surrounded by a plasma, membrane, known as
Sarcolemma
special type of smooth ER that surrounds myofibrils and stores Ca2+ for release during muscle contraction
Sarcoplasmic reticulum
Passes electrical signals, invagination of the sarcolemma and interrupts the sarcoplasmic reticulum surrounding myofibrils
Transverse tubules (T Tubules)
Enlargements of sarcoplasmic reticulum on sides of T-Tubules
Terminal cisternae
T tubule +2 terminal cisternae 
Triad
Thick filaments are made out of
Myosin
Thin filaments are made of
Actin
binds Ca2+ to displace tropomyosin to allow contraction
Troponin
Covers actin binding sites
Tropomyosin
thick and thin filaments
A band
midline section of A band,
only thick filaments
H zone
middle line of A band, hold thick filaments in position
M line
Only thin filaments
I band
both thin and elastic filaments anchor to these, define the boundaries of the sarcomere
Z discs
The myosin head moves toward the M line, pulling the actin along with it. As the actin is pulled, the filaments move approximately 10 nm toward the M line.
Powerstroke
Which are the only two in the sarcomere structure that change in length 
H zone and I band
