Physiology Notes #2 Skeletal Muscle Contraction & Relaxation
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Born2Gallop on March 29, 2011
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Physiology Notes #2
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14 terms
Terms | Definitions |
|---|---|
 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? | muscle contraction |
| As the thin filaments slide inward the Z disc come closer together and the ____ shortens: | sarcomere |
| 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 | Ca2+ SR |
| 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 | muscle fiber |
| 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: | active tension |
| Tension generated by elastic elements is called: | passive tension |
| 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 |
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