BIOL 223 Chapter 10-3
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The point at which the motor neuron connects to the skeletal muscle to stimulate contraction is the:
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
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
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
Aceytlcholine is abbreviated as:
What does the abbreviation AchE stand for?
What type of ion channel is found on the synaptic knob?
calcium ion channels
What causes the Ca ion channels to open on the synaptic knob?
an action potential in the neuron
What type of ion channel is on the postsynaptic membrane?
sodium ion channels
Why does the Na ion channel on the postsynaptic membrane open?
because an Ach binds to it's protein receptor site
What effect does the depolarization of T-tubules have on sarcoplasmic reticulum?
causes it to release Ca ions into the sarcoplasm
List the two types of ion channels found in sarcoplasmic reticulum.
- voltage-gates Ca channels
- ion pumps
Examining the initial configuration of actin, what is blocking the active sites?
When myosin heads bind to an active site on an actin myofilament they form what is known as a:
After the cross bridge is formed, the myosin head will pivot and pull the actin towards the:
True or False: The myosin filament requires the input of energy, in the form of ATP, to return to it's starting position.
Define motor unit.
a motor neuron and all the muscle fibers it innervates
A small number of muscle fibers per motor neuron gives us _______ control.
A large number of muscle fibers per motor neuron allows for _______ control.
Recruitment _______ the number of active motor units and allows for _______ powerful contraction.
The time for calcium to leave the SR and bind with the 3rd troponin subunit is known as the:
The relaxation period takes twice as long (25 ms) as the contraction period because it is a _______ process.
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)
Stimulation of the muscle before it has time to relax demonstrates:
incomplete (unfused) tetany
Complete elimination of the relaxation period before restimulation demonstrates:
complete (fused) tetany
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