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Course MSCI 522 (Spring 2025) - Principles of Physiology II
Lesson Muscle and EMG – Pre-Lab Prep
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Quick check
How many muscle bers may a single motor neuron innervate? 1 pts
Only one muscle ber
Several muscle bers
How is acetylcholine removed from the synaptic cleft? 1 pts
Acetylcholine is broken down by acetylcholinesterase in the plasma.
Acetylcholine simply di uses away from the synaptic cleft.
The enzyme acetylcholinesterase hydrolyzes the acetylcholine within the synaptic cleft.
There is a reuptake pump for acetylcholine on the presynaptic membrane.
The action potential causes the release of calcium ions from ________________ in the muscle cell. 1 pts
the cytosol
the motor end plate
the sarcoplasmic reticulum
the T tubule
What does EMG record? 1 pts
Contractions of the innervated muscle bers.
Electrical activity of the innervated muscle bers.
Electrical activity of the motor nerves supplying the muscle bers.
EMGs may be obtained from needle or surface electrode recordings. 1 pts
True
False
, Which statement regarding evoked EMG is true? 1 pts
The amplitude of the measured EMG is independent of the number of motor units recruited.
There is synchronous excitation of the muscle bers innervated by the stimulated nerve.
Which describes the phenomenon of "coactivation"? 1 pts
It is the relaxation of the antagonist muscle during the contraction of the agonist muscle.
It is the simultaneous contraction of other agonist muscles.
It is the weaker contraction of the antagonist muscle during the contraction of the agonist muscle.
Which of the following factors have been suggested as contributing to muscle fatigue? 1 pts
Loss of "central drive".
Reduction in calcium release in excitation-contraction coupling.
Reduction in muscle blood ow owing to compression of blood vessels.
All of the above.
Use the description above to help you label the components of a skeletal muscle. 1 pts
Endomysium Epimysium Fascicle Muscle Muscle ber Myo bril
Perimysium Sarcomere
Epimysium
Muscle
Perimysium
Endomysium
Fascicle
Muscle ber
Myo bril
Sarcomere
Course MSCI 522 (Spring 2025) - Principles of Physiology II
Lesson Muscle and EMG – Pre-Lab Prep
Quick check
How many muscle bers may a single motor neuron innervate? 1 pts
Only one muscle ber
Several muscle bers
How is acetylcholine removed from the synaptic cleft? 1 pts
Acetylcholine is broken down by acetylcholinesterase in the plasma.
Acetylcholine simply di uses away from the synaptic cleft.
The enzyme acetylcholinesterase hydrolyzes the acetylcholine within the synaptic cleft.
There is a reuptake pump for acetylcholine on the presynaptic membrane.
The action potential causes the release of calcium ions from ________________ in the muscle cell. 1 pts
the cytosol
the motor end plate
the sarcoplasmic reticulum
the T tubule
What does EMG record? 1 pts
Contractions of the innervated muscle bers.
Electrical activity of the innervated muscle bers.
Electrical activity of the motor nerves supplying the muscle bers.
EMGs may be obtained from needle or surface electrode recordings. 1 pts
True
False
, Which statement regarding evoked EMG is true? 1 pts
The amplitude of the measured EMG is independent of the number of motor units recruited.
There is synchronous excitation of the muscle bers innervated by the stimulated nerve.
Which describes the phenomenon of "coactivation"? 1 pts
It is the relaxation of the antagonist muscle during the contraction of the agonist muscle.
It is the simultaneous contraction of other agonist muscles.
It is the weaker contraction of the antagonist muscle during the contraction of the agonist muscle.
Which of the following factors have been suggested as contributing to muscle fatigue? 1 pts
Loss of "central drive".
Reduction in calcium release in excitation-contraction coupling.
Reduction in muscle blood ow owing to compression of blood vessels.
All of the above.
Use the description above to help you label the components of a skeletal muscle. 1 pts
Endomysium Epimysium Fascicle Muscle Muscle ber Myo bril
Perimysium Sarcomere
Epimysium
Muscle
Perimysium
Endomysium
Fascicle
Muscle ber
Myo bril
Sarcomere
