pnb 2274 lab practical 2 review UPDATED
ACTUAL Exam Questions and CORRECT
Answers
A motor unit includes: - CORRECT ANSWER - Multiple muscle fibers innervated by one
motor neuron
The EMG is a recording of: - CORRECT ANSWER - The action potentials of the
innervated muscle fibers
In this week's lab, we will be using a transducer - CORRECT ANSWER - False
(transducer converts a mechanical signal into an analog voltage
The PowerLab hardware is NOT designed to: - CORRECT ANSWER - Display a signal
reciprocal activation - CORRECT ANSWER - simultaneous activation of an agonist
muscle and inhibition of an antagonist muslce
co-contraction - CORRECT ANSWER - simultaneous contraction of both the agonist and
the antagonist muscles around a joint
The figure shown above is an example of: - CORRECT ANSWER - co-contraction
Which of the following is an acceptable scientific hypothesis? - CORRECT ANSWER -
Genetically modified tomatoes contain more fructose than conventional tomatoes.
When placing recording electrodes on the biceps and triceps: - CORRECT ANSWER -
Ensure that the electrodes are in good contact with the skin.
,During your recording, you see a flat line being recorded. What should you do? - CORRECT
ANSWER - Adjust the scale immediately.
Calculate the sampling rate in the image. It shows a rate of: - CORRECT ANSWER - 10
samples per second
What happens to your EMG signal when you increase the contraction strength? Explain the
observation. - CORRECT ANSWER - The peaks are larger
During reciprocal activation, why is the antagonist muscle not completely silent? - CORRECT
ANSWER - It is an antagonist pairing and the both work to stabilize the arm and joint
Frame your question in the form of an experimentally testable hypothesis. - CORRECT
ANSWER - If an overhead triceps extension is performed using a heavier weight, the
RMS triceps will be higher than the RMS triceps without the weight because the heavier weight
provides a greater resistance.
Design the experiment you will do to examine the hypothesis you formulated above. Make sure
you include all the equipment you will need, the number of volunteers required, and that you list
all the measurements you are going to make. - CORRECT ANSWER - In this experiment,
2 people are required. The first person will be connected to the electrodes and will be performing
the exercise with a 5 pound weight while the other person will hit the start and stop button. First
we will perform a control by recording the muscle activity while the arm is performing 3
repetitions of the exercise without a weight. After a resting period of 2 minutes, we will record
three repetitions of the overhead triceps extension using a two pound weight. After resting period
of 2 minutes, perform three repetitions of the overhead triceps extension using a five pound
weight. Compare sets of data.
Unlike the discrete waveform from an electrocardiogram, the electromyogram waveform is
irregular. Why do you suppose this is? - CORRECT ANSWER - Electrocardiograms
record cardiac muscle which all contract at the same time but electromyograms record skeletal
muscle which do not contract at the same time. These asynchronously contracting muscle fibers
cause an irregular waveform.
, Which of the following statements about electromyography (EMG) recording is NOT true? -
CORRECT ANSWER - EMG is a technique that measures the contractile force of the
muscles. EMG signals are recorded from multiple muscle fibers.
Based on your recorded EMG trace and the values you measured in Exercise 1, describe this
phenomenon qualitatively. - CORRECT ANSWER - The biceps and triceps muscles work
by reciprocal activation, meaning that while one is contracted the other is relaxed, because they
are antagonistic muscles. It is shows through the data from the table on the left. When the biceps
are contracting by flexing the arm, the biceps have a larger EMG amplitude than the triceps.
When the arm is extended, the triceps are contracting while the biceps are relaxing, which is
shown by the larger EMG amplitude in the triceps. The table on the right shows that as you
increase the weight or force that the muscles have to exert on, the EMG amplitude of the muscles
contracting together increases, as expected.
Feedback: The agonist muscle is mainly activated, while the antagonist is partially inhibited.
In your own words, explain how the EMG trace changed when you added weights to your arm?
Based on the data you collected what can you infer is happening to the muscles as weight is
added? - CORRECT ANSWER - As you increase the weight, more motor units need to be
recruited in order to contract the muscle. This was seen in the data as the electrical activity of the
muscles increased as weight was added to the arm.
Brett ate poisonous wild mushroom, which partially paralyzed his motor unit. His doctor
performed an EMG test on him and the EMG trace is shown above. Predict what normal EMG
from Brett could look like?
- CORRECT ANSWER - A normal EMG would have more regular intervals and a
higher amplitude. Because Brett's motor units are paralyzed, his muscles are not able to fully
relax before the next contraction, which doesn't allow the peaks to be as large in comparison to
the dips as they should be. The inhibition of the motor unit leads to less electrical signals being
generated.
What are your conclusions based on the recorded data? - CORRECT ANSWER - When
the weight is increased while performing an overhead tricep extension, the triceps have a larger
EMG amplitude because of increased number of motor units needed for the contraction.
Does your data support your hypothesis? Please provide some explanations in the following
space, if your data do not support your hypothesis. - CORRECT ANSWER - The data
ACTUAL Exam Questions and CORRECT
Answers
A motor unit includes: - CORRECT ANSWER - Multiple muscle fibers innervated by one
motor neuron
The EMG is a recording of: - CORRECT ANSWER - The action potentials of the
innervated muscle fibers
In this week's lab, we will be using a transducer - CORRECT ANSWER - False
(transducer converts a mechanical signal into an analog voltage
The PowerLab hardware is NOT designed to: - CORRECT ANSWER - Display a signal
reciprocal activation - CORRECT ANSWER - simultaneous activation of an agonist
muscle and inhibition of an antagonist muslce
co-contraction - CORRECT ANSWER - simultaneous contraction of both the agonist and
the antagonist muscles around a joint
The figure shown above is an example of: - CORRECT ANSWER - co-contraction
Which of the following is an acceptable scientific hypothesis? - CORRECT ANSWER -
Genetically modified tomatoes contain more fructose than conventional tomatoes.
When placing recording electrodes on the biceps and triceps: - CORRECT ANSWER -
Ensure that the electrodes are in good contact with the skin.
,During your recording, you see a flat line being recorded. What should you do? - CORRECT
ANSWER - Adjust the scale immediately.
Calculate the sampling rate in the image. It shows a rate of: - CORRECT ANSWER - 10
samples per second
What happens to your EMG signal when you increase the contraction strength? Explain the
observation. - CORRECT ANSWER - The peaks are larger
During reciprocal activation, why is the antagonist muscle not completely silent? - CORRECT
ANSWER - It is an antagonist pairing and the both work to stabilize the arm and joint
Frame your question in the form of an experimentally testable hypothesis. - CORRECT
ANSWER - If an overhead triceps extension is performed using a heavier weight, the
RMS triceps will be higher than the RMS triceps without the weight because the heavier weight
provides a greater resistance.
Design the experiment you will do to examine the hypothesis you formulated above. Make sure
you include all the equipment you will need, the number of volunteers required, and that you list
all the measurements you are going to make. - CORRECT ANSWER - In this experiment,
2 people are required. The first person will be connected to the electrodes and will be performing
the exercise with a 5 pound weight while the other person will hit the start and stop button. First
we will perform a control by recording the muscle activity while the arm is performing 3
repetitions of the exercise without a weight. After a resting period of 2 minutes, we will record
three repetitions of the overhead triceps extension using a two pound weight. After resting period
of 2 minutes, perform three repetitions of the overhead triceps extension using a five pound
weight. Compare sets of data.
Unlike the discrete waveform from an electrocardiogram, the electromyogram waveform is
irregular. Why do you suppose this is? - CORRECT ANSWER - Electrocardiograms
record cardiac muscle which all contract at the same time but electromyograms record skeletal
muscle which do not contract at the same time. These asynchronously contracting muscle fibers
cause an irregular waveform.
, Which of the following statements about electromyography (EMG) recording is NOT true? -
CORRECT ANSWER - EMG is a technique that measures the contractile force of the
muscles. EMG signals are recorded from multiple muscle fibers.
Based on your recorded EMG trace and the values you measured in Exercise 1, describe this
phenomenon qualitatively. - CORRECT ANSWER - The biceps and triceps muscles work
by reciprocal activation, meaning that while one is contracted the other is relaxed, because they
are antagonistic muscles. It is shows through the data from the table on the left. When the biceps
are contracting by flexing the arm, the biceps have a larger EMG amplitude than the triceps.
When the arm is extended, the triceps are contracting while the biceps are relaxing, which is
shown by the larger EMG amplitude in the triceps. The table on the right shows that as you
increase the weight or force that the muscles have to exert on, the EMG amplitude of the muscles
contracting together increases, as expected.
Feedback: The agonist muscle is mainly activated, while the antagonist is partially inhibited.
In your own words, explain how the EMG trace changed when you added weights to your arm?
Based on the data you collected what can you infer is happening to the muscles as weight is
added? - CORRECT ANSWER - As you increase the weight, more motor units need to be
recruited in order to contract the muscle. This was seen in the data as the electrical activity of the
muscles increased as weight was added to the arm.
Brett ate poisonous wild mushroom, which partially paralyzed his motor unit. His doctor
performed an EMG test on him and the EMG trace is shown above. Predict what normal EMG
from Brett could look like?
- CORRECT ANSWER - A normal EMG would have more regular intervals and a
higher amplitude. Because Brett's motor units are paralyzed, his muscles are not able to fully
relax before the next contraction, which doesn't allow the peaks to be as large in comparison to
the dips as they should be. The inhibition of the motor unit leads to less electrical signals being
generated.
What are your conclusions based on the recorded data? - CORRECT ANSWER - When
the weight is increased while performing an overhead tricep extension, the triceps have a larger
EMG amplitude because of increased number of motor units needed for the contraction.
Does your data support your hypothesis? Please provide some explanations in the following
space, if your data do not support your hypothesis. - CORRECT ANSWER - The data
