BIO 253 MIDTERM EXAM QUESTIONS WITH
VERIFIED ANSWERS
For each of the variables tested above what is considered to be the key influence
on tiredness? - ANSWER Activation: change in motivation or central drive
Visual Feedback: perception of effort
Rest: accumulation of lactic acid and a lowered 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? - 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 does not store significant amounts of ATP. How does the
muscle provide adequate ATP for high-intensity activity? - ANSWER Resting,
some ATP transfers a phosphate to creatine and forms phosphocreatine. This
can be used to resynthesizes ATP during high intensity 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? -
ANSWER A reduction in calcium ion release due to depletion of Ca2+ ions
from intracellular stores: The SR inhibits excitation-contraction coupling.
If you were applying sustained max force to maintain grip with the EMG
electrodes on flexor digitorum superficialis, one of the muscles involved what
, would the trace look like as you encounter fatigue for both raw data and RMS
data? - ANSWER Raw data would be spikey, and then get smaller.
It would produce, for RMS data, a nice curve that starts with a plateau sloping
down afterwards.
Why does high intensity anaerobic exercise only last in short bursts? ANSWER
Lactic acid gets broken down, which contributes to the fatigue in three ways;
impeding the contractile process, changing pH in the muscle cell. Cells tolerate
low pH only for so long. Low pH denatures the enzymes associated with
anaerobic respiration making it less effective.
What are some potential sources of error (other than equipment misuse and/or
failure to follow procedure properly) for the whole lab that might have
happened which led to your results? (LAB one) - ANSWER Interference due
to movement or sounds
Placement error (human error)
Define isometric contraction and describe an example - 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
At what stages of current did the following proportion of fibers in the muscle
were contracting?
- At threshold
- At max
- Above the maz - ANSWER - At threshold only a few of the fibers are being
recruited.
- 100% of the fibers are being recruited and contracting
VERIFIED ANSWERS
For each of the variables tested above what is considered to be the key influence
on tiredness? - ANSWER Activation: change in motivation or central drive
Visual Feedback: perception of effort
Rest: accumulation of lactic acid and a lowered 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? - 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 does not store significant amounts of ATP. How does the
muscle provide adequate ATP for high-intensity activity? - ANSWER Resting,
some ATP transfers a phosphate to creatine and forms phosphocreatine. This
can be used to resynthesizes ATP during high intensity 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? -
ANSWER A reduction in calcium ion release due to depletion of Ca2+ ions
from intracellular stores: The SR inhibits excitation-contraction coupling.
If you were applying sustained max force to maintain grip with the EMG
electrodes on flexor digitorum superficialis, one of the muscles involved what
, would the trace look like as you encounter fatigue for both raw data and RMS
data? - ANSWER Raw data would be spikey, and then get smaller.
It would produce, for RMS data, a nice curve that starts with a plateau sloping
down afterwards.
Why does high intensity anaerobic exercise only last in short bursts? ANSWER
Lactic acid gets broken down, which contributes to the fatigue in three ways;
impeding the contractile process, changing pH in the muscle cell. Cells tolerate
low pH only for so long. Low pH denatures the enzymes associated with
anaerobic respiration making it less effective.
What are some potential sources of error (other than equipment misuse and/or
failure to follow procedure properly) for the whole lab that might have
happened which led to your results? (LAB one) - ANSWER Interference due
to movement or sounds
Placement error (human error)
Define isometric contraction and describe an example - 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
At what stages of current did the following proportion of fibers in the muscle
were contracting?
- At threshold
- At max
- Above the maz - ANSWER - At threshold only a few of the fibers are being
recruited.
- 100% of the fibers are being recruited and contracting
