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13 Cards in this Set
- Front
- Back
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Explain contractile mechanism
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1. cross bridge attachment
2. power stroke-myosin head pivots 3. cross bridge detachment-requires adding ATP 4. cocking of myosin head through hydrolysis of ATP |
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What is calcium responsible for?
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entry into cell to start nerve stimulation, binding to TnC to allow myosin to bind to actin for contraction, and breaking down of glycogen
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How much calcium is actually present
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Very little inside cell, slightly more outside but still in mM.present in such small numbers because it causes so many things to happen
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Explain the neuromuscular junction
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pre-synaptic neuron
post synaptic muscle side synaptic cleft filled with fluid fusion of vesicles with acetylcholine binds to postsynaptic receptors, opens Na channels causing inside of cell to become more positive (action potential), then voltage gated channels move this electrical signal down the membrane until it reaches the t-tubule |
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What happens to the acetylcholine in this process
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it is destroyed by acetylcholinesterase as to stop to nerve stimulation
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What happens in myesthenia gravis
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the blood has antibodies to ACH receptors, therefore the antibodies are occupying the ACH receptors
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Explain muscle contraction
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Acetylcholine opens Na channel, Action potential down t-tubule to sarcoplasmic reticulum which releases calcium
Calcium released binds to TnC of the tropnin complex, conformational change contraction-myosin binds to actin pulling thick filament over thin filament Calcium removed by reuptake of calcium into sarcoplasmic reticulum-requires ATP, tropomyosin restores block of actin |
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Explain muscle contraction
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Acetylcholine opens Na channel
Action potential down the tubule to sarcoplasmic reticulum causing release of calcium Calcium released binds to troponin C -conformational change Contraction- myosin binds to actin pulling actin filament Calcium removed by reuptake of calcium into SR which requires ATP, Tropomyosin restores block of actin |
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Sliding Filament theory
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1. thin filament slides past thick filament
2. increased stretch (increased degree of overlap, the more possibility of myosin forming crossbridges with actin)- which increases muscle contraction 3. When muscle contracts (must be stimulated by MOTOR nueron) does so in all or nothing fashion |
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what does is mean to pull a muscle?
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pull the thin filament so far pat thick filament, myosin heads can't reach the actin to make crossbridges
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What is a motor unit?
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a motor neuron and all the fibers it innervates
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What is the average number of fibers per motor neuron
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150 although you have thousands in your hips and only 4 in your eyes
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what is meant by latency period?
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delay in time from electrical stimulation to actual contraction- excitation contraction coupling
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