lect 7- muscle tissue 2 Flashcards
how are cardiac muscle fibers attached
end to end by intercalated discs
how many nuclei are in cardiac muscle and where are they located
located centrally (one or occasionally 2)
compare T tubules of skeletal muscle vs cardiac
cardiac T tubules are larger
where are T tubules located in cardiac muscle
Z lines
where to mitochondria lie in cardiac muscle
parallel to I bands
what is the source of ANF
atrial granules
what specializations make up the transverse portion of the intercalated discs
fascia adherens and desmosomes
what does the longitudinal portions of the intercalated discs contain
gap junctions
_______ are specialized conducting cells of the AV bundle
purkinje fibers
where are the few myofibrils of purkinje fibers located
peripherally
what are smooth muscle cells surrounded by
reticular fiber network
explain the shape and nuclei of smooth muscle
are fusiform in shape with a single centrally placed nucleus
what do dense bodies contain and what do they function as
contain alpha-actinic and function as myofilament attachment sites
what are the intermediate filaments in nonvascular smooth muscle cells
desmin
what are the intermediate filaments in vascular smooth muscle
vimentin
what do gap junctions facilitate
the spread of excitation
what are sarcolemmal vesicles/caveolae similar to
smooth ER
what is the innervation of smooth muscle provided by
sympathetic and parasympathetic nerves of the ANS
where are nerve terminals of smooth muscle observed
close to the muscle within the endomysium
what is vascular smooth muscle contraction usually initiated by
nerve impulse
describe visceral smooth muscle contraction
it is myogenic (stretch) and the signal spreads from cell to cell via gap junctions
what are smooth muscle cells most responsive to (hormone)
epinephrine
what does dystrophin do
links the actin cytoskeleton of muscle to the external lamina
what occurs if dystrophin is absent
abnormal muscle fiber fragility
