Anatomy Chapter 8
What is the thin filament?
actin
What makes calcium leave its storage area?
action potential traveling down the t-tubules triggering a release
How does exercise change a muscle cell?
causes cell to create more fibers and thus be stronger
What are the t-tubules an extension of?
cell membrane
Where else is calcium involved in muscle movement?
end bulb where it allows synaptic vesicles to bind to cell membrane and release acytlecholine into the cleft
How does calcium get back into the storage area?
enzyme pumps (requires ATP)
What is the difference between a contracted and relaxed sarcomere?
fibers close or far apart, actin connected to myosin or not
Why do muscles look striped?
filaments look stripy
What cartoon step could explain the need for threshold?
h
Which step in your cartoon makes the muscle contract?
l
What is sarcoplasm?
muscle cell cytoplasm
What is treppe?
muscle gets stronger as it first contracts
How does the sliding muscle filament theory explain muscle movement?
muscles move because the filaments slide between each other, shortening the muscle
What is the thick filament?
myosin
Why can't cross-bridges always attach to actin?
need atp to attach and move the tropomyosin so arms can attach to myosin binding sites
Why do you need ATP for both contracting and relaxing?
need it to let myosin hands grab onto the muscle, also need to pump calcium back into the terminal cisterns so the stimulus stops
What is a sarcomere?
one bundle of actin and myosin
Why can muscles only pull, not push?
relaxed state is as far apart as the thick and thin filaments can get, they can only pull or get closer can only shorten
What are terminal cisterns an extension of?
sarcoplasmic reticulum
How big are muscle cells?
skinny and long
Why is there so little room for sarcoplasm in muscle cells?
so full of actin-myosin bundles
What is the all-or-nothing principle?
stimulus is either big enough for an action potential or not. there is only one sized action potential
Where is calcium stored in a muscle cell?
terminal cisterns
What happens when calcium is put back into the storage area?
the muscle relaxes because binding sites no longer exposed to myosin sidearms
How can the cross bridges provide enough force to shorten a muscle cell?
with the help of ATP
