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muscle (components of a muscle cell (sarcolemma = plasma membrane, nuclei,…
muscle
components of a muscle cell
sarcolemma = plasma membrane
nuclei
mitochondria
sarcoplasm = cytoplasm
transverse (t) tubule
sarcoplasmic reticulum
myofibril
= contains multiple sarcomeres
sarcomere = repeating unit between two Z lines
myosin (thick, think morbid)
actin (thin, think anorexic)
titin
troponin etc
1) skeletal muscle tissue
formation
a myocyte (1 muscle cell = 1 muscle fiber) forms due to fusing of mesodermal cells called myoblasts
multi-nucleated
(peripherally positioned)
organization:
the skeletal muscle is an organ encased in
epimysium
(casing), that is composed of
muscle fascicles
, which are covered in
perimysium
. The muscle fascicle is composed of muscle fibers which are encased in
endomysium
.
tetrad = 2 SR + 1 t-tubule at Z line
striated
potential is initiated by graded potential at neuro-muscular junction when somatic neurons release Ach and Na+ channels open
2)
cardiac muscle tissue
each cardiac muscle cell remains separate
single centrally located nucleus
designed for high freq. rhythmic contractions that are highly coordinated
this is accomplished using
gap junctions
which in these cells exist along the
intercalcated discs
diad = 1 SR + 1 t-tubule at Z line
striated
3) smooth muscle tissue
one centrally located nuclei
NOT striated
location:
unitary muscle in viscera except in the heart
function:
to contract