lect 6- muscle tissue I Flashcards
what is the activity of skeletal muscle
strong, quick, discontinuous voluntary contraction
what is the activity of cardiac muscle
strong, quick and continue involuntary contractions
what is the activity of smooth muscle
weak, slow involuntary contraction
what is the sarcolemma equivalent to
cell membrane
what is the sarcoplasm
cytoplasm of muscle cells
________ surrounds the entire muscle cell
epimysium
________ invests each fascicle
perimysium
______ envelopes each fiber (muscle cell)
endomysium
how many types of fibers/cells is skeletal muscle made up of
three
what type of fibers red fibers
slow fibers
what type of fibers are white fibers
fast
what type of cytochemical staining do red fibers show for ATPase
weak
what type of cytochemical staining do white fibers show for ATPase
marketable
what are white fibers rich in
phosphorylases
how does the A band appear with light microscopy
bright when examined with polarized light (although it is darkly stained with ordinary histological dyes)
describe the I band with light microscopy
it is isotropic and appears dark when exampled with polarized light, but it is lightly stained in routine histological preparations
define the Z disc/line
dense area that bisects the I band
define the H band
it transects the A band and has a dark M line in its center
what is the distance between 2 successive Z lines called
sarcomere
what is the functional unit of contraction in striated muscle
sarcomere
what is the plasma membrane that envelopes skeletal muscle fibers called
sarcolemma
where are the nuclei located in skeletal muscle
in peripheral location just beneath the sarcolemma
what is the cytoplasm of the muscle fiber called
sarcoplasm
what does the sarcoplasmic reticulum surround
surrounds myofilaments and forms a meshwork around each myofibril
what does the sarcoplasmic reticulum sequester
calcium ions
where are triads of skeletal muscle located
at the A-I junction
what type of filaments does the I band have
thin filaments which anchor at the dense Z line
what type of filaments does the A band consist of
both thick and thin filaments (making it anisotropic)
what is the M line formed by
cross connections at the midpoints of the thick filaments
what type of filaments does the H band have
thick filaments
what occurs at the heads of myosin filaments of thick myofilaments
ATP hydrolysis as well as the location for the actin-binding site
what type of actin do thin myofilaments primary have
F actin (which is formed by polymerization of G actin monomers)
describe the 3 subunits of troponin
TnC binds to calcium ions, TnT binds to tropomyosin, and TnI prevents the interaction between actin and myosin
when is contraction of skeletal muscle fibers initiated
when calcium binds to the TnC unit of troponin
