Muscle Flashcards
cilia and flagella are outgrowths of
cell membrane
flagellar movement helps in
swimming of spermatozoa
maintenance of water current in canal system of sponges
locomotion of protozoans like Euglena
embryonical origin of muscle
mesoderm
how much percent of our body weight is muscles
40-50
special properties of muscles
excitability
contractility
extensibility
elasticity
three types of muscles
skeletal
smooth / visceral
cardiac
a skeletal muscle is made up of bundles of
fascicles
fascicles are held together by
fascia (collagenous connective tissue)
plasma membrane of a muscle fibre
sarcolemma
cytoplasm of muscle fibre
sarcoplasm
sarcoplasm contains many nuclei
hence, state of muscle fibre
syncytium
endoplasmic reticulum of muscle fibre
sarcoplasmic reticulum
sarcoplasmic reticulum is the store hous of which ions
calcium
band that contains actin
I band (isotropic)
band that contains myosin
A band (anisotropic)
thick filament
myosin
thin filament
actin
elastic fibre which bisects the I band
Z line
fibrous membrane which bisects the A band
M line
portion of myofibril between two successive Z lines
sarcomere
in resting state, non overlapping zone is of thick filaments is called
H zone
each ____ actin is a polymer of monomeric ____ actins
F (filamentous)
G (globular)
two filaments of another protein _______________ run close to F actins throughout its length
tropomyosin
a complex protein ___________ is distributed at regular intervals on tropomyosin
troponin
in resting state, a subunit of troponin masks __________________________ on actin filament
myosin binding site
monomer of myosin is called
meromyosin
parts of a meromyosin
globular head with a short arm
tail
globular head and short arm are called
heavy meromyosin (HMM)
tail is called
light meromyosin (LMM)
heavy meromyosin has binding sites for ____________ and ____________
therefore, it is called ___________ enzyme
actin
atp
atpase
mechanism of muscle contraction is best explained by which theory
sliding filament
what does sliding filament theory state
that contraction of a muscle fibre takes place by sliding of the thin filaments over the thick filaments
muscle contraction is initiated by a signal sent by _______ via _________
CNS
motor neuron
a motor neuron along with muscle fibres connected to it constitute
motor unit
junction between a motor neuron and sarcolemma of muscle fibre
neuromuscular junction / motor-end plate
a neural signal reaching the neuromuscular junction releases ________________________ which generates ________________________ in sarcolemma
neurotransmitter - acetyl choline
action potential
action potential spreads through the muscle fibre and causes
release of calcium ions in the sarcoplasm
increase in calcium ion levels leads to
binding of calcium ion with a subunit of troponin and thereby remove masking of myosin binding site
utilising energy from ___________________, myosin head now binds to exposed sites on action to form _______________
atp hydrolysis
cross bridge
during contraction of sarcomere, _______ retains the length and _____________ gets reduced
A band
I band
myosin, releasing ____________ goes back to relaxed state
adp and ip
how is cross bridge broken
a new atp binds to myosin
till when does this cycle continue
till calcium ions are pumped back to the sarcoplasmic reticulum which results in the masking of actin filaments
repeated activation of muscles can lead to accumulation of ______________ due to anaerobic breakdown of glycogen, causing ___________
lactic acid
fatigue
red coloured oxygen storing pigment
myoglobin
reddish appearance in some muscles is due to
high content of myoglobin
reddish muscles are called
red muscle fibres
amount of mitochondria in red muscles and why
high amount
to form more atp using stored oxygen aerobically
why do some muscles appear pale or whitish
less content of myoglobin
amount of mitochondria in white muscles and why
less amount
depend on anaerobic processes for energy
amount of sarcoplasmic reticulum in white fibres
high
