Which of the following terms are NOT used interchangeably? |
motor unit – motor neuron |
Which of the following is NOT a phase of a muscle twitch? |
shortening phase |
Where does the acetylcholine that stimulates muscle contraction bind? |
receptors in the motor end plate |
When acetylcholine binds to its receptors, it results in __________. |
the end plate potential, a graded depolarization, and a change in ion permeability |
Which of the following occurs during the latent period of muscle contraction? |
Calcium is released from the sarcoplasmic reticulum. |
As the stimulus voltage was increased in this activity, which of the following occurred? |
The muscle force generated increased. |
Which of the following describes the relaxation phase? |
The sarcomeres are increasing in length, and the force generated decreases. |
Which of the following can trigger a muscle twitch? |
release of acetylcholine or electrical stimulation |
Which of the following is proportional to the amount of tension produced by a skeletal muscle? |
the number of motor units activated |
NO force is generated during which of the following? |
the latent period |
What is the minimum voltage needed to generate active force in the skeletal muscle? |
threshold voltage |
A motor unit is defined as _______. |
the axon terminals of a single motor neuron and all of the muscle fibers that it stimulates |
In the lab, a researcher finds that the threshold stimulus to induce an action potential in a muscle fiber’s sarcolemma was 3.0 volts. Which of the following would result in muscle tension? |
3.0 volts and 4.0 volts |
Increasing the applied voltage in the simulation corresponds to which in vivo event? |
motor unit recruitment |
As the stimulus voltage increased, the resulting muscle tension _____. |
increased to a point until it reached a plateau |
Which of the following occurs during the contraction phase? |
Cross-bridge cycling is taking place. |
Treppe is the phenomenon that results in _______. |
a progressive increase in the force generated with repetitive stimulation |
When the frequency of stimulation of a muscle is great enough, _______. |
wave summation results and muscle twitches overlap. |
When wave summation occurs, _______. |
the muscle force generated increases |
Why does wave summation occur? |
Muscle fibers are partially contracted when the next stimulus arrives. |
Which of the following produced an increase in stimulus intensity? |
increasing the voltage applied |
Which of the following produced an increase in stimulus frequency? |
clicking the mouse in rapid succession |
Which of the following does NOT describe treppe? |
An increase in stimulus intensity is required to see the effect. |
Which of the following occurs if the load attempted is equal to or greater than the force generated by a muscle? |
Isometric muscle contraction occurs. |
The resting length of the muscle _______. |
occurs when the muscle is relaxed |
The graph of the length-tension relationship illustrates _______. |
the optimal sarcomere length for muscle contraction and the amount of overlap between the thick and thin filaments in the resting muscle |
Which of the following is generated when cross-bridges form between actin and myosin? |
active force |
Which of the following describes the relationship between length and tension? |
The active force can increase or decrease, depending on the starting resting length of the muscle. |
Why does the active force of skeletal muscle change with the muscle’s resting length? |
The number of cross-bridges between actin and myosin varies. |
Which starting length of the muscle provided the maximum total force? |
the longest starting length |
At which muscle length was the passive force the greatest? |
100 mm |
A&P PhysioEx Skeletal Muscle Lab
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