myosin heads attache to and walk along the thin filaments at both ends of a sarcomere, progressively pulling the thin filaments toward the center of a sarcomere cases this to happen?
As the thin filaments slide inward the Z disc come closer together and the ____ shortens:
The contraction cycle is the repeating of events that causes sliding of the filaments. Name the sequence of this event:
1. myosin ATPase hydrolyzes ATP & become energized
2. the myosin heads attached to the actin
3. the myosin head generates forces as it rotates toward the center of the sarcomere (power stroke)
4 biding of ATP to myosin detaches myosin from actin & the myosin head again hydrolyzes the ATP, retunes to its original position and binds to a new site on actin as the cycle continues.
An increase in Ca2+ concentration in the cytosol starts ______ whereas a decrease turns ___ off.
filament sliding & a decrease tuns off the sliding process
The muscle action potential propagating into the T tubule system causes opening of ___ release channels in the _____ membrane
Calcium ions diffuse from the SR into the cytosol and combing with troponin causing?
the troponin-tropomyosin complex to move away from the myosin-binding sites on the actin
When the concentration of calcium ions in the cytosol decreases the troponin-tropomyosin complex slide back over and block the myosin-binding sites and _____ relaxes
A muscle fiber develops its greatest tension when there is an optimal zone of overlap between ____&___ filaments
thick & thin (this dependence is the length-tension relationship)
Tension generated by contractile elements is called:
Tension generated by elastic elements is called:
This junction is the synapse between a somatic motor neuron and a skeletal muscle fiber:
neuromuscular junction (NMJ)
The neuromuscular junction (NMJ) includes:
1. axon terminals
2. synaptic end bulbs of a motor neuron
3. adjacent motor end plate of the muscle fiber sarcolemma
When a nerve impulse reaches the synaptic end bulbs of a somatic motor neuron it triggers what?
exocytosis of the synaptic vesicles
This initiates a muscle action potential:
when ach diffuses across the synaptic cleft and binds to ach receptors