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The point at which the motor neuron connects to the skeletal muscle to stimulate contraction is the:
neuromuscular junction
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What are the three steps of muscle contraction that occur in the synaptic knob?
- action potential opens calcium channels
- influx of calcium ions stimulates production Ach vesicles
- Ach is released, via exocytosis, into the synaptic cleft
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What are the three steps of muscle contraction that occur in/on the postsynaptic cell?
- Ach binds to ligand-gated Na channels
- influx of sodium causes membrane depolarization
- action potential in the muscle causes contraction
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What are the four steps that occur to the neurotransmitter after muscle contraction is achieved?
- Ach removes from receptor site with the help of AchE
- acetic acid is stripped of and diffuses away
- choline flows back into the synaptic knob
- choline rebinds with an acetic acid to form Ach
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Aceytlcholine is abbreviated as:
Ach
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What does the abbreviation AchE stand for?
aceytlcholinesterase
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What type of ion channel is found on the synaptic knob?
calcium ion channels
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What causes the Ca ion channels to open on the synaptic knob?
an action potential in the neuron
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What type of ion channel is on the postsynaptic membrane?
sodium ion channels
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Why does the Na ion channel on the postsynaptic membrane open?
because an Ach binds to it's protein receptor site
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What effect does the depolarization of T-tubules have on sarcoplasmic reticulum?
causes it to release Ca ions into the sarcoplasm
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List the two types of ion channels found in sarcoplasmic reticulum.
- voltage-gates Ca channels
- ion pumps
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Examining the initial configuration of actin, what is blocking the active sites?
tropomyosin
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When myosin heads bind to an active site on an actin myofilament they form what is known as a:
cross bridge
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After the cross bridge is formed, the myosin head will pivot and pull the actin towards the:
M line
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True or False: The myosin filament requires the input of energy, in the form of ATP, to return to it's starting position.
True
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Define motor unit.
a motor neuron and all the muscle fibers it innervates
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A small number of muscle fibers per motor neuron gives us _______ control.
precise
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A large number of muscle fibers per motor neuron allows for _______ control.
strength
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Recruitment _______ the number of active motor units and allows for _______ powerful contraction.
increases, more
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The time for calcium to leave the SR and bind with the 3rd troponin subunit is known as the:
latent period
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The relaxation period takes twice as long (25 ms) as the contraction period because it is a _______ process.
passive
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What two things are responsible for the increasing tension observed during wave summation?
- increased availability of calcium ions
- begins from a position of increased tension (length-tension principle)
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Stimulation of the muscle before it has time to relax demonstrates:
incomplete (unfused) tetany
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Complete elimination of the relaxation period before restimulation demonstrates:
complete (fused) tetany
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