6.3 lecture - muscle EMs, cytoskeleton, & embryology Flashcards
in smooth muscle, calcium is
start
the sarcoplasmic reticulum ends in tubular structures called
terminal cisternae
VGCa++ channels in t-tubules
DHP dihydropyridine receptors
T/F in all types of muscle, calcium is shuttled into the cell via caveolae and sequestered in the SR until an electrical signal is received
true
in addation to actin, dense bodies bind to intermediate filaments, which are typically __ in visceral muscle and __ in vascular muscle
desmin in visceral smooth muscle
vimentin in vascular smooth muscle
what are the intermediate filaments in:
- visceral smooth muscle
- vascular smooth muscle
- desmin
- vimentin
this intermediate filament connects Z-lines of myofibrils with each other
desmin
muscular dystrophy is due to a problem with this protein
dystrophin
part of costamere complex that anchors Z lines to sarcolemma
muscular dystrophy is due to a lack of this protein
dystrophin
part of costamere complex that anchors Z lines to sarcolemma
myotube
early formation with central nuclei and a few peripheral myofibers that will eventually grow into myofibers of adult skeletal muscle
T/F adult myofibers can increase in number
false
can only change in size by addition or subtraction of myofibrils
how are muscle external membrane, nerve external membrane, and basement membrane functionally similar?
serves as scaffolding for tissue repair
-disruption makes regeneration response more difficult
T/F intermediate filaments seem to have little importance in skeletal muscle
true
T/F cardiac and skeletal muscle contain intermediate filaments
true
connecting Z-lines and anchoring z-lines to costameres
why is the occasional cardiac myocyte binucleated?
failure of division
not a combination to form a functional syncytium as with skeletal muscle
T/F cardiac cells can have multiple nuclei within sarcolemma
true
occasionally a failure of division results in binucleated cardiac myocytes
what 3 junctions does an intercalated disk consist of?
fascia adherens (actin + catenin) desmosomes (intermediate filament + catenin) gap junctions
other than myocytes, other specialized cardiac cells include
cardiac endocrine cell (mostly atrial)
cardiac conducting cell (in myocardial layer)
which layer of heart wall has major blood vessels?
epicardium
how would a type I red muscle fiber compare to a type IIb white muscle fiber on H&E?
*not going to be able to tell the difference, need PAS stain
BUT if really pressed to try:
white probably larger
red probably more darkly eosinophilic (more mitochondria)
how would a type I red muscle fiber compare to a type IIb white muscle fiber on H&E?
white probably larger
red probably more darkly eosinophilic (more mitochondria)
chief materials of:
lamina lucida
lamina densa
lamina retucularis
lucida - glycoproteins (laminin, fibronectin)
densa - type IV collagen
reticularis - type IV collagen; type VII collagen
chief materials of:
lamina lucida
lamina densa
lamina retucularis
lucida - glycoproteins (laminin, fibronectin)
densa - type IV collagen
reticularis - type IV collagen; type VII collagen
T/F satellite cells are within external membrane of muscle fiber but outside sarcolemma
true
but will never be able to make this out on LM
quiescent precursors that become activated to divide and differentiate in response to the needs of muscle growth and damage
satellite cells (quiescent but actively monitoring and moving along surface)
T/F external membrane is a barrier to neurotransmitter and therefore does not exist in neuromuscular junciton
false
not a barrier to NT
exists in NMJ same as everywhere else
T/F external membrane is a barrier to neurotransmitter and therefore does not exist in neuromuscular junciton
false
not a barrier to NT
exists in NMJ same as everywhere else
T/F adipocytes have an external membrane
true
muscle cells
nervous cells
adipocytes
T/F smooth muscle motor end plates have junctional folds
false
at least not as significantly as skeletal muscle
T/F smooth muscle motor end plates have junctional folds
false
at least not as significantly as skeletal muscle
why do muscle spindle and golgi tendon organ include small muscle fibers in addition to nerves?
muscle fiber contracts and stretches proportionally to the other fibers so that nerves can sense length in the case of the muscle spindle and force exerted in the case of the golgi tendon organ
why do muscle spindle and golgi tendon organ include small muscle fibers in addition to nerves?
muscle fiber contracts and stretches proportionally to the other fibers so that nerves can sense length in the case of the muscle spindle and force exerted in the case of the golgi tendon organ
muscle spindle is encapsulated by …
perimysium (kind of a perineurium too)
musculotendinous junction
actin filaments directly anchored to cell membrane in structure similar to fascia adherens
musculotendinous junction
actin filaments directly anchored to cell membrane in structure similar to fascia adherens
what does an muscle external membrane directly surround?
plasmalemma bound units, including:
-skeletal muscle fibers
-cardiac myocytes
-smooth muscle cells
NOT skeletal muscle fascicles (not directly)
NOT smooth muscle bundles (not directly)
NOT skeletal muscle fibrils (not directly)
what does an muscle external membrane directly surround?
plasmalemma bound units, including:
-skeletal muscle fibers
-cardiac myocytes
-smooth muscle cells
NOT skeletal muscle fascicles (not directly)
NOT smooth muscle bundles (not directly)
NOT skeletal muscle fibrils (not directly)
what will break first, plasmalemma or external membrane?
plasmalemma
(external membrane is very tough)
-can have broken plasma membrane but intact external membrane
