Muscle Flashcards
skeletal muscle
attached to bone
striated
voluntary
nuclei around periphery
cardiac muscle
heart
striated
involuntary - controlled by CNS
nuclei in the center
smooth muscle
lacks striation
lines hollow organs
involuntary - controlled by CNS
sarcoplasm
cytoplasm of muscle cells
what controls involuntary muscles?
CNS
muscle fiber
each muscle cell is multinucleated
syncytium
multinucleated muscle fiber
endomysium
delicate layer of reticular fibers that surrounds muscle fibers (cells)
perimysium
thicker CT than endomysium
surrounds fascicles (bundles of muscle fibers)
fascicles
bundles of muscle fibers surrounded by perimysium
epimysium
sheath of dense CT that surrounds collections of fascicles (the entire muscle)
myofibril
structural subunits of muscle fibers
sarcolemma
cell membrane
surrounds muscle fiber
sarcoplasmic reticulum
smooth ER surrounding myofibrils
thin filaments
actin
thick filaments
myosin
Z line
dense outer line
alpha actin
M line
center of the A band
H band
just thick filaments
sarcomere
basic contractile unit of striated muscle
titan
longest protein known
polypeptide chain stretches along the whole sarcomere
functions as molecular spring
What does “decorating” represent?
the unipolarity of thin filaments
what does ATP function as in skeletal muscle?
dissociate myosin from the thin filament
also to move the myosin head via energy from hydrolysis
What does Ca control in skeletal muscle?
contraction/relaxation by binding to a site on troponin which alters tropomyosin’s position exposing the myosin binding site on actin
E-C coupling
binding of acetylcholine from neuron depolarizes sarcolemma and T-tubules which triggers Ca release from SR
muscle spindle
sits in perimysium around fascicles
special nerve fibers for proprioception
Type I slow oxidative
red and slow
contracting
marathoner
Type IIa
fast oxidative
Fast
sprinter
Type IIb
fast glycolytic
very fast
pale muscles
weight lifter
satellite cell
precursor to myofibers
located between cell membrane and basement membrane
stimulate for increased growth
dystrophin
is thought to link
laminin, which resides in the external lamina of the muscle
cell, to actin filaments. Absence of this protein is associated
with progressive muscular weakness, a genetic condition
called Duchenne’s muscular dystrophy. Dystrophin is
encoded on the X chromosome, which explains why only
boys suffer from Duchenne’s muscular dystrophy. Recently, characterization of the dystrophin gene and its product has
been clinically important
Unique to cardiac muscle
cardiac nuclei in middle
cardiac functional syncytium
T-tubules are larger
intercalated disks with adherins, desmosomes, and gap junctions
functional syncytium
cardiac muscle
can have 2 nuclei but intercalated disks prevent it from being really multinucleated like skeletal muscle
syncytium
skeletal cell - multinucleated
atrial granules
found in atria of heart
release ANF and BNF by exocytosis
Calmodulin
what Ca binds to in smooth muscle
activates a myosin light chain kinase
