Muscle contraction Flashcards
is the muscle cell, mulit or singular nucleated
multi-nucleated
approximatly how many myofibrils are packed together
~1000
what happens when sarcomere contracts
length of filament doesnt change but overlap does
how is contraction caused
active sliding of thin and thick filaments past each other
what are thick filaments mostly made of
myosin
what are thin filaments mostly made of
actin
what is the M line mostly made of
myomesin and M-protein
what is the z line mostly made of
alpha-actin
what is the quantity of myosin
very large (520kda) and very abundant
how many chains are involved
2 large heavy and 4 small light
what does heavy meromyosin form
cross bridges
what does F-actin intertwine to form
base of thin filament where troponin/myosin attaches
what does light myosin form
filaments spontaensouly
what does F-actin do
increase rate at which Adp and Pi are released from active site
what are isoforms
varients arising from RNA editing or alternative splicing
calciums role in muscle contraction
controls binding of myosin to F-actin via troponin/myosin
Tnl binds to what
actin
Tnc binds to what
Ca2+
Tnt binds to what
tropomyosin
what happens when acetylcholine is released into the synaptic cleft
binds to 2 alpha subunits dilating the core allowing Na+ to flow into cytosol with fewer K+ leaving
what is exitation contraction coupling
linking neuron to muscle contraction
how does transmission of Action pot occur
across transverse tubules causes opening of a Ca2+ channel
why is ryanodine poisonous
it blocks calcium release from the SR, resulting in paralysis
what activates muscle contraction
binding of Ca2+ to Tnc
what is require for contraction and relaxation
energy
approximatly how many ATP molecules are required for a single muscle twitch
~7.5billion
