PNB PRACTICAL 2 EXAM QUESTIONS
AND ANSWERS ALL CORRECT
When placing recording electrodes on the biceps and triceps:
Place electrodes near hairy areas.
Consider placing it on the surface of tendons and joints.
Ensure that the electrodes are in good contact with the skin.
Place the ground electrode close to the recording electrode. - Answer- Ensure that the
electrodes are in good contact with the skin.
Which of the following statements about electromyography (EMG) recording is NOT
true?
Attaching electrodes to hairy or bony area on the skin will give bad electrical contact.
EMG is a technique that measures the contractile force of the muscles.
The signal recorded by EMG is from multiple muscle fibers.
In our experiment, integrated instead of raw data is used for value measurement. -
Answer- EMG is a technique that measures the contractile force of the muscles
How does the size of sheep olfactory bulbs compare with those of humans? Is the
sense of smell more important as a protective and a food-getting sense in sheep or in
humans? - Answer- It is larger in proportion than in humans because animals rely on
smell as a defense than humans do. Thus the sense of smell is more important as a
protective and a food-getting sense in sheep.
What are the structural differences between sheep's mammillary body and human
mammillary body? - Answer- Sheep only have one mammillary body while humans
have two, however the size of the mammillary body is large in sheep than in humans.
Does smooth muscle tissue fatigue? - Answer- Smooth muscles do not fatigue. Smooth
muscle is able to maintain slow, forceful contractions for extended periods.
Describe how the isolated muscle behaved as it was stretched progressively. - Answer-
The force of the contraction increases as it approaches optimal length but then
decreases as it goes past the optimal length.
What effect does stretching the muscle have on contraction strength? Is this effect
linear? - Answer- At the cellular level, actin and myosin are arranged so they slide past
each other. These protein molecules must overlap in order to interact with each other.
As the muscle stretches, it contracts more forcibly to some maximum force. Past this
point, the actin and myosin layers begin to be pulled apart. As less and less of these
, proteins overlap, the muscles produces less and less force. The effect is not linear, as
the contraction force increases at first then decreases.
What stretch length will result in the highest contraction force? What happens to the
muscle at the highest stretch levels? - Answer- A moderate stretch level will result in the
largest contraction force. At high stretch levels, the actin and myosin firmaments overlap
too little. Therefore, contractile forces decreases.
Events at NMJ
Influx of Ca2+ into presynaptic axon terminal.
Sodium influx through receptor channels.
Binding of ACh to receptors on the muscle membrane.
Stimulation of action potential in motor neuron.
Vesicle docking and release.
Action potential propagates along muscle membrane.
Diffusion of ACh across the synaptic cleft. - Answer- 1. Stimulation of action potential in
the motor neuron
2. Influx of Ca2+ into presynaptic axon terminal
3. Vesicle docking and release
4. Diffusion of ACh across the synaptic cleft
5. Binding of ACh to receptors on the muscle membrane
6. Sodium influx through the receptor channels
7. Action potential along the muscle membrane
Motor Unit - Answer- a single motor neuron and the muscle fibers it innervates
Recruitment refers to:
Multiple twitches in one fiber of one motor unit.
Twitches in all the fibers of several motor units.
One twitch in multiple fibers of one motor unit. - Answer- Twitches in all the fibers of
several motor units.
One motor unit can respond with multiple twitches per stimulus.
True
False - Answer- False
What is the optimal sarcomere length for maximal force generation in muscle?
Fully stretched
Intermediate length
Completely contracted - Answer- Intermediate length
A single motor neuron innervates one muscle fiber.
True
False - Answer- False
Which of the following is NOT a mechanism of fatigue?
AND ANSWERS ALL CORRECT
When placing recording electrodes on the biceps and triceps:
Place electrodes near hairy areas.
Consider placing it on the surface of tendons and joints.
Ensure that the electrodes are in good contact with the skin.
Place the ground electrode close to the recording electrode. - Answer- Ensure that the
electrodes are in good contact with the skin.
Which of the following statements about electromyography (EMG) recording is NOT
true?
Attaching electrodes to hairy or bony area on the skin will give bad electrical contact.
EMG is a technique that measures the contractile force of the muscles.
The signal recorded by EMG is from multiple muscle fibers.
In our experiment, integrated instead of raw data is used for value measurement. -
Answer- EMG is a technique that measures the contractile force of the muscles
How does the size of sheep olfactory bulbs compare with those of humans? Is the
sense of smell more important as a protective and a food-getting sense in sheep or in
humans? - Answer- It is larger in proportion than in humans because animals rely on
smell as a defense than humans do. Thus the sense of smell is more important as a
protective and a food-getting sense in sheep.
What are the structural differences between sheep's mammillary body and human
mammillary body? - Answer- Sheep only have one mammillary body while humans
have two, however the size of the mammillary body is large in sheep than in humans.
Does smooth muscle tissue fatigue? - Answer- Smooth muscles do not fatigue. Smooth
muscle is able to maintain slow, forceful contractions for extended periods.
Describe how the isolated muscle behaved as it was stretched progressively. - Answer-
The force of the contraction increases as it approaches optimal length but then
decreases as it goes past the optimal length.
What effect does stretching the muscle have on contraction strength? Is this effect
linear? - Answer- At the cellular level, actin and myosin are arranged so they slide past
each other. These protein molecules must overlap in order to interact with each other.
As the muscle stretches, it contracts more forcibly to some maximum force. Past this
point, the actin and myosin layers begin to be pulled apart. As less and less of these
, proteins overlap, the muscles produces less and less force. The effect is not linear, as
the contraction force increases at first then decreases.
What stretch length will result in the highest contraction force? What happens to the
muscle at the highest stretch levels? - Answer- A moderate stretch level will result in the
largest contraction force. At high stretch levels, the actin and myosin firmaments overlap
too little. Therefore, contractile forces decreases.
Events at NMJ
Influx of Ca2+ into presynaptic axon terminal.
Sodium influx through receptor channels.
Binding of ACh to receptors on the muscle membrane.
Stimulation of action potential in motor neuron.
Vesicle docking and release.
Action potential propagates along muscle membrane.
Diffusion of ACh across the synaptic cleft. - Answer- 1. Stimulation of action potential in
the motor neuron
2. Influx of Ca2+ into presynaptic axon terminal
3. Vesicle docking and release
4. Diffusion of ACh across the synaptic cleft
5. Binding of ACh to receptors on the muscle membrane
6. Sodium influx through the receptor channels
7. Action potential along the muscle membrane
Motor Unit - Answer- a single motor neuron and the muscle fibers it innervates
Recruitment refers to:
Multiple twitches in one fiber of one motor unit.
Twitches in all the fibers of several motor units.
One twitch in multiple fibers of one motor unit. - Answer- Twitches in all the fibers of
several motor units.
One motor unit can respond with multiple twitches per stimulus.
True
False - Answer- False
What is the optimal sarcomere length for maximal force generation in muscle?
Fully stretched
Intermediate length
Completely contracted - Answer- Intermediate length
A single motor neuron innervates one muscle fiber.
True
False - Answer- False
Which of the following is NOT a mechanism of fatigue?
