BIO 253 Midterm UPDATED ACTUAL
Exam Questions and CORRECT Answers
What are the main causes of fatigue addressed for each of the variables tested? - CORRECT
ANSWER - Encouragement: Change in motivation or central drive
Visual Feedback: Sense of effort
Rest: Build-up of lactic acid and a reduction in blood flow
What would you expect from a person's EMG who has Muscular Dystrophy who is asked to lift a
weight? How would that differ from a person with Myasthenia Gravis? - CORRECT
ANSWER - Muscular Dystrophy: EMG would look the same as normal individual despite
the muscle cells dying, the nerve signal is unaffected.
Myasthenia Gravis: EMG would look weaker and fatigue faster than a normal individual
The muscle cell doesnt stockpile large quantities of ATP. How does the muscle ensure enough
ATP for intense exercise? - CORRECT ANSWER - At rest, some ATP transfers a
phosphate to creatine and creates phosphocreatine. This can be used to resynthesizes ATP during
intense exercise for the contraction to continue.
During repeated skeletal muscle contraction, what happens to calcium within a single motor unit
that may lead to fatigue? What is it's overall effect? - CORRECT ANSWER - A reduction
in calcium ion release due to depletion of Ca2+ ions from intracellular stores: The SR inhibits
excitation-contraction coupling.
If EMG electrodes were placed on the flexor digitorum superficialis (one of the muscles involved
in maintaining grip) while applying sustained max force, what would the EMG trace look like as
you encounter fatigue for both the raw data and the RMS data? - CORRECT ANSWER -
Raw data would be spikey, and then get smaller.
RMS data would be a nice curve that starts as a plateau and then slopes down
Why is high intensity anaerobic exercise limited in duration? - CORRECT ANSWER -
Lactic acid breaks down and contributes to fatigue by interfering with contractile processes and
, by changing the pH of the muscle cell. The tolerance for decreasing pH in muscle cells is limited.
As pH decreases, enzymes denature and anaerobic respiration becomes inefficient.
What could be some sources of error (that do not include improper use of the equipment or not
following procedure correctly) in this whole lab that could have affected your data? (LAB one) -
CORRECT ANSWER - Interference due to movement or sounds
Placement error (human error)
Define isometric contraction and describe an example - CORRECT ANSWER - An
isometric contraction is a muscle contraction that sees the muscle remain at the same length in
which there is no movement of the joint.
Holding a wallsit is an example
When the current reached the following stages, what proportion of fibers in the muscle were
contracting?
- At threshold
- At max
- Above the maz - CORRECT ANSWER - - At threshold only a few of the fibers are being
recruited.
- 100% of the fibers are being recruited and contracting
- still 100% because all of the fibers are being used
A short period of rapid electrical stimuli is used to observe muscle fibers contracting
continuously (tetanus). Chemical agents can cause tetanus by interfering with the motor neurons.
These agents include a toxin produced by the soil bacterium Clostridium tetani which produces a
toxin that blocks inhibitory signals to motor neurons. One of the symptoms of these agents is
called "spastic paralysis". Explain how the nervous system effects of clostridium tetani toxin
would result in tetanus in a muscle. How might this lead to a life threatening condition? -
CORRECT ANSWER - If the muscles required for breathing were involved death could
follow
Explain what is happening at the synaptic clef during summation, incomplete tetanus, and
tetanus. - CORRECT ANSWER - During summation, stimuli occur one after the other, but
Exam Questions and CORRECT Answers
What are the main causes of fatigue addressed for each of the variables tested? - CORRECT
ANSWER - Encouragement: Change in motivation or central drive
Visual Feedback: Sense of effort
Rest: Build-up of lactic acid and a reduction in blood flow
What would you expect from a person's EMG who has Muscular Dystrophy who is asked to lift a
weight? How would that differ from a person with Myasthenia Gravis? - CORRECT
ANSWER - Muscular Dystrophy: EMG would look the same as normal individual despite
the muscle cells dying, the nerve signal is unaffected.
Myasthenia Gravis: EMG would look weaker and fatigue faster than a normal individual
The muscle cell doesnt stockpile large quantities of ATP. How does the muscle ensure enough
ATP for intense exercise? - CORRECT ANSWER - At rest, some ATP transfers a
phosphate to creatine and creates phosphocreatine. This can be used to resynthesizes ATP during
intense exercise for the contraction to continue.
During repeated skeletal muscle contraction, what happens to calcium within a single motor unit
that may lead to fatigue? What is it's overall effect? - CORRECT ANSWER - A reduction
in calcium ion release due to depletion of Ca2+ ions from intracellular stores: The SR inhibits
excitation-contraction coupling.
If EMG electrodes were placed on the flexor digitorum superficialis (one of the muscles involved
in maintaining grip) while applying sustained max force, what would the EMG trace look like as
you encounter fatigue for both the raw data and the RMS data? - CORRECT ANSWER -
Raw data would be spikey, and then get smaller.
RMS data would be a nice curve that starts as a plateau and then slopes down
Why is high intensity anaerobic exercise limited in duration? - CORRECT ANSWER -
Lactic acid breaks down and contributes to fatigue by interfering with contractile processes and
, by changing the pH of the muscle cell. The tolerance for decreasing pH in muscle cells is limited.
As pH decreases, enzymes denature and anaerobic respiration becomes inefficient.
What could be some sources of error (that do not include improper use of the equipment or not
following procedure correctly) in this whole lab that could have affected your data? (LAB one) -
CORRECT ANSWER - Interference due to movement or sounds
Placement error (human error)
Define isometric contraction and describe an example - CORRECT ANSWER - An
isometric contraction is a muscle contraction that sees the muscle remain at the same length in
which there is no movement of the joint.
Holding a wallsit is an example
When the current reached the following stages, what proportion of fibers in the muscle were
contracting?
- At threshold
- At max
- Above the maz - CORRECT ANSWER - - At threshold only a few of the fibers are being
recruited.
- 100% of the fibers are being recruited and contracting
- still 100% because all of the fibers are being used
A short period of rapid electrical stimuli is used to observe muscle fibers contracting
continuously (tetanus). Chemical agents can cause tetanus by interfering with the motor neurons.
These agents include a toxin produced by the soil bacterium Clostridium tetani which produces a
toxin that blocks inhibitory signals to motor neurons. One of the symptoms of these agents is
called "spastic paralysis". Explain how the nervous system effects of clostridium tetani toxin
would result in tetanus in a muscle. How might this lead to a life threatening condition? -
CORRECT ANSWER - If the muscles required for breathing were involved death could
follow
Explain what is happening at the synaptic clef during summation, incomplete tetanus, and
tetanus. - CORRECT ANSWER - During summation, stimuli occur one after the other, but
