Muscle Tissue Flashcards
What is the function of muscle
contraction
what is found in their cytoplasm
contractile fibres - also the cytoplasm
what is the force produced by
movement of the actin fibres over the myosin fibres
what are the types of msucle cells
skeletal
cardiac
smooth
what is myoepithelial cells
epithelial cells which have muscle like properties
what are myofibroblasts
connective tissue with contractile elements
what is pericytes relating to
vessels
what are myoepithelial cells associated with + example
secretory units of the exocrine glands
~ salivary or memory glands
what is the shape of myopeithlial
flattened cells
what does the myopeithelial contain
protein arrnagmenet similar to smooth muscle
what is myofibroblasts like charasertically
fibroblasts and smooth muscle cells
what is the number of myofibrilblasts like normally
few in number
what happens to myofibrilblasts during injury
what happens at the end
they englarge and proliferate and secrete cologne to provide a scaffold
they contract the wound
pericytes are found where
capillaries and venules
what do pericytes act like
stem cells
what do pericytes control
capillary diameter by contractile properties
what muscle types have straitions
skeletal and cardiac
branching of different muscles
skeletal - unbranched
cardiac - branched
smooth - branched
what is the skeletal msucle nuclei like
size, shape , location
long
oval
in the peripheral part
what do the cells look like for skeletal muscle
long cylindrical multinucleted cells
what is the siize of skeletal muscle
10 - 100um
1000 - 200000 um length
where does differeination of skeletal muscle start
mesenchymal cells (myoblasts) of mesoderm
what happens to the myoblasts for skeletal muscle
align and fuse together to make long multinucated myotubes
what happens to myotubes - skeletal muscle
syntehise proteins that make up the myofilament and begin to show strations
what happens to further development of the myofilaments - skeletal muscle
the nulcei dispalce peripherally against the sarcolemma
how are satellite cells formed
some of the myoblasts population does not fuse or differenatie but remains mesenchymal cells
where do these satellitecells locate themselves
external surface but inside the developing external lamina
what is the function of satellite cells
proliferate and produce new muscle fibres after injrury
What is the organisational levels of skeletal muscle
scaromoere - myofibril - muscle fibre - one facile - one muscle
what is the functional unit of skeletal muscle
sarcomere
what is a fasicle
muscle fibres boundled together
what is eipmysium
surrounds whole muscle
perimysium
surrounds single fasicle
enomysium
sourrinding a single muscle fibre
what are the dark and light bands also called
Dark band - A
Light band - I
what does Anisotropic (A) mean
fibres are altered in polarised light
what does isotropic mean (I)
fibres do not alter under polarised light
how do the thick and thin filament sit among each other
they overlap
why is a hexagon shape formed by A an I bands
overlapping of light and dark shows each thick filament is surrounded by 6 thin filaments
Where is thick filament found
occur A band
where does thin filament run
between and parallel to thicj filament and have one end attached to the Z disc
what does the I band consist of
portion of thin filament that do not overlap the thick filament
what is the A band composed of
mainly thick filament plus the overlapping portion of thin filament
What is the H zone
only thick filament
What is the M line
lateral connections are made between teo adjacent thick thinaments
what is the thin filament composed of
tropomyosin
g actin
f actin
active sites
trophin complex
what is fecular actin formed by
by individual Globular actin
where is tropomyosin located
located in thegroove between two tiwsed actin strands
What are the different types of Troponin
I , C T
what does troponin T do
attaches to tropomyosin
what does troponin C do
attach to calcium ions
What does troponin I do
inhibits actin myosin interactions
what does thick filament consists of moslty
myosin
what is the head of thick filament
two globular heads of myosin
how are motor end plates formed
expnded motor axon terminals
what will motor axon terminals form
neuromuscular junctions with the membrane of the muscle cell
what does binding of a receptor do
initate the muscle fibre depolarisation which goes into the myofibrils and the t tubule
how many muscle fibres does one motor nueron innervate
10 to several hundred muscle fibres
what does fewer muscle fibres in a motor unit do to control movement
create finer control of movement
what is a motor end plate
special type of synapse on the surface of a muscle membrane
what does folding membrane in the sarcolemma increase
number of Ach receptors in the nmj
what is t tubules
branches of Sarcoplasmic membrane surrounding myofibril at the Ai junction of each scaromere
what does the scaroplasmic reticulum contain
very higher concentration of calcium ions and small branches
where is the sarcoplasmic reticulum lie
either side of the tubules
what is sarcoplasmic reticulum
netwrok of specliased smooth endoplasmic retciulum
what is triad
t tubule associated with the sarcomere is flanked by segment of sarcoplasmic reticulum three three together is known as a triad
events of muscle contraction
- nerve impulses triggers the release of acetylchloine at the neuromuscular junction
- acetylcholine binds to the motor end plate of the sarcolemma and intiates an impulse in the muscle fibre
- the impulse spread quickly to the tibules which releases calcium ions from the cisternae of sarcoplasmic reticulum
- the calcium will bind to the troponin complex on the actin filament
- exposed active site on the actin will attach to the myosin heads
- myosin heads utilises ATP to slide to the actin filament over them
- sarcomere short and thus the muscle will contract
What is the sliding filament model scarmoere
H zone - shorter
I band - shorter
A band - same
what are the stages of the sliding filament together
- binding of myosin to the actin
- power stroke - cross bridge pulling myofilament inward
- detachment - cross bridge detached and returns to original set
- cross bridge binds to more distal actin molecule
what is type I skeletal muscle fibres
slow, red and oxidiative
what is type II A
fast, intermediate oxidative glycolytic fibres
what is the type II B
fast white and glycolytic fires
what is myotendinous junction
specliased junction collagen of tendon attaches to end of the muscle fibres
where do sensory nerve exons penetrate
wrap around individual intrafusal fibre
what is the cardiac muscle made of
mesodermal cells
what is intercalated disc
have abudent desmosomes
what is dyad
one branch sarcoplasmic reticulum associated with each t tuble forming dyad rather than a triad
what is the role of satellite cells in skeletal remodelling
under the basal lamina press aginst the outer surface of the sarcolemma and proliferate and form ner fibres
what is the diameter of smooth muscle
5um and 20 - 500 um
what does acin and mysoin crisscross obliquely through the cell
formimg a lattice like network and contract by sliding filament mechanism
wht is troponin in smooth muscle
calmodulin
what is the MCLK
pjopshorylate myosin
what is the intermediate filament
desmin - i all mooth muscles
vimentin - in vascular smooth muscles
what is smooth muscle contraction regulated by
autonomic nerves or certain hormones
