Muscles Flashcards
(38 cards)
sarcolemma
cytosol of a muscle cell
sacroplasm
cytoplasm of a muscle cell
sarcomere
gives striation to the muscle cell
made up of thick and thin filaments
fundamental to muscle contraction
motor unit
= 1 motor neuron + all the muscle fibers the neuron innervates
those with fewer muscle fibers are better for precise movement
characteristics of muscle fibers
excitability
contractibility
extendability
elasticity
parts of a sarcomere
A-band I-band H-zone M-line Z-line
A-band
myosin filaments
I-band
actin filaments and Z-line
H-zone
area of myosin that DOESN’T overlap
M-line
middle of myosin filament
Z-line
anchored actin filament
what changes in the sarcomere when a muscle contracts?
z-lines move closer together
I-band shortens
H-zone disappears
what are thin filaments mostly made of?
actin filaments
what are thick filaments mostly made of?
myosin
anatomy of myosin
head: binds actin
neck and tail: have variable lengths
which myosin type is present in muscles?
myosin II
myosin II
aka muscle myosin
has very long tail region that gives the structure of thick filaments
myosin I
acts as an anchor between the cell membrane and the cytoskeleton
myosin V
transports various cargo molecules
one of the main transport molecules
proteins involved in regulating access to myosin binding sites
troponin
tropomyosin
tropomyosin
binds and obscures myosin binding sites
troponin
respond to calcium ions
troponin subunits
TnC: binds to calcium ions
TnI: interacts with actin and obscures the binding site
TnT: interacts with tropomyosin
proteins responsible for changes in intracellular calcium ion concentration
ATPase SERCA sodium/calcium reversible exchanger L-type calcium channel RyR