w8 histology of muscle Flashcards
spindle-shaped central nucleus, no striations which muscle tissue, single cells, single central nucleus
smooth muscle
linear branched, single central nucleus, intercalated discs
cardiac muscle
elongated, striated many peripheral nuclei
skeletal muscle
largest striated peripheral nuclei
skeletal
branched intercalated discs, striated central nuclei (larger cytoplasm to nuclear ratio)
cylindrical cells arranged end to end, fatty acids as a major fuel
cardiac
smallest fusiform, not striated, central nuclei (small cytoplasm to nuclear ratio)
smooth
surrounds single muscle fiber (cells)
runs parallel to muscle fibers
contains small blood vessels, fine neuron branches
endomysium
-surrounds the facicles (bundles) of muscle fibers
-larger blood vessels and nerves travel here
perimysium
-covers entire skeletal muscle
-major vascular and nerve supply penetrates here
epimysium
structural and functional unit of muscle fiber is what
myofibril
myofibrils are composed of bundles of what
myofilaments
what gives the straited appearance
myofilaments
which is thick and thin myofilaments
myosin - thick
actin - thin
sarcomere is between what lines
Z lines
A band includes what myofilaments
actin and myosin
I band includes what myofilaments
actin only
what is the most clincally important accessory protein and what does it do
dystrophin
links actin in outermost myofilaments to transmembrane proteins and eventually to fibrous endomysium surrounding the entire muscle cell
which bands shorten and do not
A band does not shorten
H band shorterns
I band has the distance between A bands of successive sacromeres shorten
H band includes what myofilament
only myosin
what are invaginations of plasma membrane
invaginations of the sarcolemma penetrating into the myocyte interior, forming a highly branched and interconnected network that makes junctions with the sarcoplasmic reticulum.
T tubules
what role does SR (smooth ER of muscle) play in muscle
calcium storage, release, re-uptake
what are dilated portions of SR
terminal cisterna
what is the contact between a T-tubule and 2 terminal cisternae
triad
what is rigor mortis
permanent contraction due to depletion fo ATP postmortem
muscle cells unable to prevent calcium entry therefore myosin binds to actin
what is the stretch receptor
muscle spindle
multinucleated syncytium is formed by fusion of what
myoblast
syncytium
A large cell-like structure formed by the joining together of two or more cell
satellite cell function and location
Satellite cells are myogenic stem cells responsible for muscle regeneration throughout the lifespan (skeletal muscle repair)
between the sarcolemma and basal lamina of their associated muscle fiber
how is the mitochondria number in cardiac muscle and where are the glycogen storage
numerous large mitochondria
glycogen stores adjacent to each myofibril
how do cardaic T tubulers compare w skeletal muscle
larger, and located at the level of the Z line
in cardiac muscle, portion of the sarcoplasmic reticulum adjacent to T tubule is organized as a what
diad
intercalated disc contains what kind of junctions
gap junctions, fascia adherens, desmosomes
in transverse regions between cardiac muscle cells, what do fascia adherens and desmosomes do
bind cells together, prevents separation during contraction cycles
what type natriuretic factor is elevated in congestive heart failure
B type
what systems innervate/stimulate cardiac muscle
sympathetic and parasympathic
(modify rate of contraction but do not initiate it)
can cardiac tissue regenerate in adult humans?
no
what muscle has the greatest capacity to regenerate
smooth muscle, capable of dividing
close to endothelial cells of blood capillaries and small venules (source of new smooth muscle cells repair damage)
pericytes
what do dense bodies do and what do they attach to
serve as anchors from which the thin filaments can exert force (analogous to Z lines)
attach to actin and intermediate filaments
are there T tubules in smooth muscle contraction
no
contraction speed and energy use compared to skeletal muscle
smooth muscle contracts more slowly and uses less energy than skeletal muscle
(lower myosin ATPase activity results in slower contraction)
(slower rate of Ca2+ removal results in slower relaxation)
what nerve endings release acetylcholine or norepinephrine
autonomic nerve endings
what may depolarize spontaneously or in response to chemicals binding to receptors linked to G-proteins
hormones and local factors
lack of oxygen, histamine, excess CO2, low pH may signal what
signal contraction by affecting Ca2+ entry into the sarcoplasm
smooth muscle innervation done by what axon terminals
autonomic
smooth muscle what kind of junctions connect adjacent cells
gap junctions
smooth muscle cells can synthesize what
collagen, elastin, proteoglycans,
(influences extracellular matrix)
