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12 Cards in this Set
- Front
- Back
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What are the two strands of the actin filament?
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Tropomyosin
F-actin |
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Troponin
- attached to what? - initiates what? |
Attached to tropomyosin
Contraction |
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During contraction, what what bands shrink?
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H band
I band Z band (sarcomere) |
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Myosin heads attach to what?
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Active sites on actin filament
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Describe the transmission at the neuromuscular junction.
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Nerve AP reaches axon terminal
Depolarization opens voltage-gated calcium channels Calcium influx causes exocytosis of ACh into synaptic cleft ACh binds to receptors on Post Junctional Membrane (PJM) or Post Synaptic Membrane ACh-binded receptors will increase Na+ permeability via ligand-gated channels. Influx of sodium will depolarize muscle cell membrane. |
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Describe the activity after the neuromuscular junction is activated?
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Depolarization spreads along muscle membrane
Depolarization makes to T-tubules which are close to Sarcoplasmic reticulum (SR) SR releases calcium Calcium binds to Troponin C Troponin C changes conformation which forces tropomyosin out of the way. Now, myosin head is free to attach actin. Sarcomere shortens |
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List energy resources for muscles
(in order of least efficient to most) |
Cellular ATP (1-2 sec)
Phosphocreatine (5-8 sec) Intramuscular Glycogen (1 min) Oxidative Phosphorylation (hrs) |
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Fast fibers:
- size - extensive what (why?) - Lots of what? |
Large
Sarcoplasmic reticulum (fast release of Ca2+) Glycolytic enzymes |
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Slow fibers:
- size - extensive what (why?) - Lots of what? |
Small
Blood supply (for large provisions of oxygen) Mitochondria & Myoglobin |
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What happens after muscle denervation?
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Atrophy
(immediate) Degenerative changes in muscle (after 2 months) Most muscle fibers destroyed & replaced by fibrous fatty tissue. (Final stages) |
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How does Poliomyelitis affect muscles?
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Kills motor neurons
(lasts temporarily) Surviving MACROmotor units sprout new axons. No micromotor units, thus FINE MOTOR CONTROL IS LOST |
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How does Rigor Mortis affect the muscles?
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After death, all muscles go into constant contracture
b/c there is NO ATP release myosin heads and to pump out Calcium (via Calcium ATPase) |
