muscle tissue Flashcards
Each muscle cell contains ___ . Individual ___ are composed of thick and thin __ which are responsible for contraction.
myofibrils
myofibrils
myofilaments
Thick and thin myofilaments overlap in the darker __ band and only thin myofilaments are present in the lighter __ band
A
I
Within a fascicle, an individual myocyte is surrounded by reticular fibers which form the
endomysium (separates muscle fibers)
Each fascicle is surrounded by dense irregular connective tissue called
perimysium( contains muscle fibers)
Most muscles are surrounded on the outer surface by a dense irregular connective tissue layer called
epimysium (covers the muscle)
sarcolemma invaginations at the A-I band junction in mammals and at the Z line in amphibians
T tubules
In skeletal muscle , each T tubule form a
triad
center= t tubule
sids - SER
SER stores
calcium
What is a motor unit composed of
A nerve fiber and the muscle cell to innervates
The point of attachment of a nerve within a skeletal muscle fiber
motor end plate
What are the three binding sites for troponin
Binds with tropomyosin
binds with actin
binds with calcium
What happens in rigor mortis
ATP is depleted the filaments cannot detach
Red skeletal muscle fibers (Type I) get energy from what pathway. White muscle fibers?
Oxidative pathway
Glycolytic pathway
These fibers contract and fatigue slowly , slow twitch fibers
red fibers
More extensive SER, rapid release of calcium , fast twitch fibers
white fibers
regeneration of skeletal muscle
depend on extent of injury
small areas of muscle can be regenerated through fusion of satellite cells with each other to form new muscle cells or fusion with existing muscle cells
if damage is extensive, skeletal muscle cells is replaced by connective tissue
in cardiac muscle, t tubules are located where
The SER forms a __ - t tubule and 1 see on one side
at z lines
diad
Cardiac muscles contain intercalated disk that contain :
gap junctions
desmosomes
fascia adherens (located between desmosomes)
what are purkinje fibers
impulse conducting, modified cardiac fibers located in interventricular septum
they occur in groups
in cardiac muscles , calcium is released from where
SER and t tubules
is there regeneration in cardiac m. cells
no
but can be repaired by proliferation of connective tissue rather than regeneration
nuclei in skeletal m.
multi nucleated and located at peripheral
nuclei in cardiac m.
nucleus is in center of cell, intercalated disks
smooth muscle cell shape
spindle -shaped, elongated
Smooth muscle lacks troponin, what does calcium bind with in smooth muscle
calmodulin protein
smooth muscle lack t tubules
true
Gap junctions in smooth muscle are located in sarcolemma are called
nexus
what is unitary smooth muscle
contract at 1 time as a unit .spreads from cell to cell by gap junctions
unitary skeletal muscle is found
in the viscera of digestive system
what is multi unit skeletal muscle
triggered by a nerve impulse, lack gap junctions, results in reduced coordination between cells
multi skeletal muscle examples
constrictor and dilator muscle cells of the iris
regeneration of skeletal muscle cells
it is limited
healing of new smooth m cells is mainly through connective tissue scar formation
which muscle has highest regeneration
smooth muscle
purkinje fibers vs cardiac fibers
are less striated
contain more glycogen
diameter is larger than in cardiac fiber
