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29 Cards in this Set
- Front
- Back
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What are the borders of the sarcomere?
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Z line to Z line
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What's in the middle of the H zone?
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the M line
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In tropomyosin, there is one ____ every 7 actins.
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troponin
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What are the three parts of troponin?
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ICT
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What is the crossbridge cycle?
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The process of actin and myosin linking and contracting the sarcomere.
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Steps of the cross bridge cycle
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Steps
1. Myosin hydrolyzes ATP 2. Myosin and actin attach 3. Myosin kicks out Pi 4. Myosin kicks out ADP 5. ATP is added to the AM complex 6. A detaches from M-ATP |
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What happens when Pi is released during the cross bride cycle?
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The hinge region stretches and the orientation of the head changes.
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What is the rigor step of the cross bridge cycle?
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When actin and myosin are attached and Pi and ADP have already left the complex.
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What is the duty cycle of the cross bridge cycle?
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It's the proportion of time that myosin and actin are attached to one another.
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How do the duty cycles of skeletal/cardiac muscle and smooth muscle differ?
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The duty cycle of smooth muscle is high, meaning A and M prefer to be attached.
In skeletal/cardiac muscle, A and M prefer to be detached. |
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What is excitation-contraction coupling?
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The coversion of an electrical signal to mechanical contraction.
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What is calcium induced calcium release?
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The ryanodine receptor of the sarcoplamic reticulum binds intracellular calcium, triggering even more calcium release
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Calcium binds to ____, lifting the tropomyosin chain, allowing ___ to bind.
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troponin; myosin
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T-tubule depolariztion opens voltage gated _____, which in turn triggers ______.
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calcium channel (dihydropyridine receptor); calcium induced calcium release (via ryanodine receptor on SR)
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What are the components of a motor unit?
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The motor unit and the muscle fibers that it innervates (5 - 100+)
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If you stain a motor neuron with glycogen, the fibers it innervates will deplete the glycogen and appear ___.
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white
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Small motor units have a ___ threshold for action potentials compared to larger motor units.
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lower
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What is spatial summation?
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Fibers with different motor neurons are activated depending on their different thresholds, so gradation is possible.
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Which kinds of motor units will be recruited first?
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small units
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How does the contraction of ocular muscles differ from that of postural muscles?
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Ocular muscles have a very quick contraction. Quick on, quick off. Postural muscles are the opposite.
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Why is the twitch of occular muscles so much faster than that of postural muscles?
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The cross bridge cycles of these two muscles differ. They have differ myosin types with different kinds of APTases.
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Are small motor units associated with slow or fast ATPases?
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slow ATPases in myosin
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What does creatine kinase do?
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It turns ATP and ADP back and forth in muscle and brain. PhosphoCreatine can only be used by muscle.
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Most energy used for muscle contraction comes from _____.
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PCr
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During acute muscle atrophy, your fibers will shift toward what type?
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the fast type
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During chronic atrophy, what kinds of fibers are lost?
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The fastest, most powerful type.
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It takes about ____ as long to regain muscle mass than it does to lose it.
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twice
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What two things are being used in therapeutic trials to enhance muscle regeneration?
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IGF and myostatin
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What is heterotopic ossification?
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Aberrant formation of bone in muscle after injury.
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