11.2 – Skeletal muscle cells Flashcards
which stem cells fuse to form a muscle fiber?
myoblasts
when a muscle is injured, cells called ___ cells can multiply and help repair the damage
satellite
which membranous structures conduct impulses thru the sarcoplasm to stimulate the release of calcium?
T-tubules
in a myofibril, a thick filament is composed of pairs of ___ molecules intertwined together
myosin
which unspecialized cells are located b/n a muscle fiber and the endomysium?
satellite cells
what is found in thin filaments?
fibrous (F) actin
globular (G) actin
tropomyosin
troponin
which cells help regenerate damaged skeletal muscle?
satellite cells
in a myofibril, the ___ filaments stabilize the thick filaments and prevent over-stretching
elastic
what is the function of T-tubules?
to stimulate the terminal cisternae to release calcium
what is found in thin filaments but is not a regulatory protein?
actin
infoldings of the sarcolemma, called transverse tubules, as associated w/ 2 terminal cistern, forming a unit called a ___
triad
what happens when calcium ions bind to troponin?
tropomyosin moves off the active site on actin
which protein makes up the thick filaments of a myofibril?
myosin
what causes skeletal muscle cells to be striated?
the alternating light and dark regions of the sarcomeres
thin filaments are primarily composed of which protein?
F actin
in a sarcomere, the thick filaments attach to the ___ line, found in the middle of the H band.
M
elastic filaments in a myofibril are made of which protein?
titin
in a thin filament, each tropomyosin molecule has a small calcium-binding protein called ___ bound to it
troponin
which is true of the light bands in skeletal muscle?
they are called I bands and are bisected by a Z disc
“I” in “light”
what are 2 contractile proteins found in a myofibil?
actin
myosin
w/in skeletal muscle cells, what extends from one Z disc to the next and constitutes one contractile unit?
sarcomere
under the microscope, muscle that has alternating light and dark regions is said to be which of the following?
striated
the dark bands in the striations of skeletal muscle are called ___ bands and they represent the ___
A
overlap of actin and myosin
in a myofibril, the ___ filaments stabilize the thick filaments and prevent over-stretching
elastic
w/in a sarcomere, the region within the A band that lacks thin filaments is called the ___ band
H
the portion of a myofibril from one Z disc to the next is called a(n) ___
sarcomere
in a sarcomere, the thick filaments attach to the ___ line, found in the middle of the H band
M
