11.4 – Behavior of skeletal muscle fibers Flashcards
which occurs during muscle contraction?
the overlapping of myofilaments increases
what is a neuromuscular junction?
a site where a nerve fiber communicates w/ a muscle fiber
what does the sliding filament theory describe?
muscle contraction
during cross-bridge formation, the cocked head of myosin attaches to what on the thin filament?
active site
when acetylcholine binds to its receptors on the motor end plate, an ion channel opens and ___ ions diffuse quickly into the muscle cell
sodium
during contraction, what causes a power stroke?
when myosin releases ADP and ratchets to a low energy position
(when myosin head releases ADP, it moves to the low energy position. When it binds ATP, it moves to the high energy position)
what is the function of a T tubule?
T tubules carry the action potential thru the sarcoplasm
the step in which the muscle fiber develops tension and may shorten is called
contraction
what is the role of acetylcholinesterase?
it breaks down ACh, ending muscle stimulation
the prevailing theory regarding muscle contraction is called the ___ filament theory
sliding
during relaxation, active-transport pumps in the sarcoplasmic reticulum move which ion from the sarcoplasm into the cisternae?
calcium
which forms a cross-bridge?
a cocked head of myosin bound to actin
why are elastic elements important to muscle function?
elastic elements provide the recoil that helps return the sarcomere to its resting length
what is a power stroke during muscle contraction?
the ratcheting of a myosin head
how does an action potential move deep into the muscle cell?
via the T-tubules
