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85 terms · Human A & P, Lab SC Prof. S. Herrick Human Anatomy & Physiology Laboratory Manual, 11th ed. Cat, ISBN: 9780321822192
What is the period of time that elapses between the generation of an action potential and the start of muscle tension development in a muscle fiber?
a. the relaxed period
b. the contractile period
*c. the latent period
d. the recess period
Will changes to the stimulus voltage alter the duration of the latent period?
a. Yes, changing the stimulus voltage will change the latent period duration proportionately.
*b. No, changing the stimulus voltage will not change the latent period duration.
What occurs during the latent period of these isometric contractions?
a. The length of the muscle fiber is sliding into an optimal length.
*b. All the steps of excitation-contraction coupling occur.
c. Muscle fiber cross bridges are cycling at sub-maximal rates.
d. The required amounts of ATP are being generated.
An action potential in a motor neuron triggers the release of which neurotransmitter?
a. glutamate
*b. acetylcholine
c. glycine
d. norepinephrine
The term skeletal muscle fiber refers to
*a. an individual skeletal muscle cell
b. an isolated skeletal muscle, such as the biceps or triceps
c. an individual myosin fiber
d. an individual sarcomere
The graded depolarization in the skeletal muscle fiber that is elicited in response to one action potential from the motor neuron is called
a. an EPSP (excitatory postsynaptic potential)
b. an IPSP (inhibitory postsynaptic potential)
*c. an EPP (end-plate potential)
d. a threshold potential
Which of the following is not a phase of a skeletal muscle twitch?
a. contraction
*b. hyperpolarization
c. latent
d. relaxation
A skeletal muscle twitch is
*a. one contractile response to a single action potential
b. one contractile response to a train of action potentials
c. multiple contractile responses to a train of action potentials
d. multiple contractile responses to a single action potential
Which of the following correctly matches the twitch phase with its definition?
a. latent: time from peak tension until end of muscle contraction
b. contraction: time between an action potential in a muscle cell and the start of muscle tension
c. relaxation: time between electrical stimuli
*d. contraction: time between the end of the latent period and peak muscle tension
Skeletal muscles are connected to bones by
tendons
Skeletal muscles are composed of hundreds to thousands of individuals cells called
fibers
Motor unit refers to
1 motor neuron and all of the skeletal muscle fibers it innervates
The motor neuron and muscle fiber intersect at what is called the
neuromuscular junction
Skeletal muscle fibers are innervated by
a. parasympathetic neurons
b. sympathetic neurons
*c. motor neurons
d. interneurons
A single action potential propagating down a motor axon results in
a. several AP's and several contractile events in the muscle fibers it innervates
b. several AP's and a single contractile event in the muscle fibers it innervates
c. a single action potential and several contractile events in the muscle fibers it innervates
*d. a single action potential and a single contractile event in the muscle fibers it innervates
In resting skeletal muscle, calcium is stored in the
a. sarcomere
b. myofibril
*c. sarcoplasmic reticulum
d. cytosol
During the latent period for an isometric contraction
a. the actin & myosin filaments slide past each other, causing the muscle to shorten
b. force is generated by the muscle
*c. the cellular events involved in excitation-contraction coupling occur
d. a single twitch occurs
What do you see in the active force display when the stimulus voltage is set to 0.0, and why does this observation make sense?
*a. 0.00 g; there was no activation of skeletal muscle fibers by this stimulus
b. 0.00 g; this low stimulus voltage activates only a few skeletal muscle fibers
c. 0.00 g; once skeletal muscle is isolated from the body and mounted on the transducer stand, it can no longer generate active force when stimulated
What is the lowest stimulus voltage that induces active force in the skeletal muscle?
a. menial stimulus
*b. threshold voltage
c. minimus voltage
d. adequate stimulus
As the stimulus voltage is increased from 1.0 volt up to 10 volts, what will happen to the amount of active force generated with each stimulus?
a. The active force will continually increase
b. The active force will not increase above the value observed when 1.0 volt is applied
*c. The active force will first increase and then plateau at some maximal value as the stimulus voltage increases
d. The active force will first increase and then decrease
e. The muscle will catch fire and set off sprinkler systems
Motor unit recruitment refers to
*a. an increase in the number of active muscle fibers to increase the force developed in a muscle
b. an increase in the number of active muscle fibers to decrease the work a muscle must perform
c. a decrease in the number of active muscle fibers to increase the simplicity of force development in a muscle
d. a decrease in the number of active muscle fibers to decrease the force developed in a muscle
Active tension (or force) in a skeletal muscle fiber results from
a. activation of cross bridge cycling via increased intracellular calcium levels
b. stretching the muscle before applying the stimulus voltage
c. moving the muscle on its support stand
d. detachment of the tendons from the bones in the body
*a. activation of cross bridge cycling via increased intracellular calcium levels
b. stretching the muscle before applying the stimulus voltage
c. moving the muscle on its support stand
d. detachment of the tendons from the bones in the body
The _______ voltage is the minimal stimulus needed to cause a depolarization of the muscle plasma membrane (sarcolemma)
a. motor unit voltage
b. maximal voltage
c. latent voltage
d. threshold voltage
a. motor unit voltage
b. maximal voltage
c. latent voltage
*d. threshold voltage
By definition, the _____ voltage is the amount of stimulus required to successfully recruit all of the muscle fibers into developing active force.
a. latent
b. contractile stimulus
c. maximal
d. motor unit
a. latent
b. contractile stimulus
*c. maximal
d. motor unit
Why was a maximal voltage observed in this experiment?
a. The maximal voltage induces the most calcium release from a muscle fiber's sarcoplasmic reticulum
b. At the maximal voltage, all the muscle fibers contained in this muscle are depolarized and they all develop active force
c. The maximal voltage induces the most ACh release from a muscle fiber's sarcolemma
d. The maximal voltage induces the fastest cross-bridge cycles.
a. The maximal voltage induces the most calcium release from a muscle fiber's sarcoplasmic reticulum
*b. At the maximal voltage, all the muscle fibers contained in this muscle are depolarized and they all develop active force
c. The maximal voltage induces the most ACh release from a muscle fiber's sarcolemma
d. The maximal voltage induces the fastest cross-bridge cycles.
A sufficiently strong electrical stimulus applied to an isolated, mounted skeletal muscle induces the development of muscle force, or muscle tension. Which of the following statements concerning this observation is true?
a. As the strength of the electrical stimulus is increased, the latent period changes in length
b. The electrical stimulus only influences the skeletal muscle fibers that are in immediate contact with the electrodes
c. The electrical stimulus mimics ACh release at a neuromuscular junction
d. As the strength of the electrical stimulus is increased, the amount of force each individual muscle fiber generates also increases
a. As the strength of the electrical stimulus is increased, the latent period changes in length
b. The electrical stimulus only influences the skeletal muscle fibers that are in immediate contact with the electrodes
*c. The electrical stimulus mimics ACh release at a neuromuscular junction
d. As the strength of the electrical stimulus is increased, the amount of force each individual muscle fiber generates also increases
Treppe
progressive increase in force generated when a muscle is stimulated in succession, such that twitches follow closely with each subsequent twitch peaking slightly higher than the prior
During a single twitch of a skeletal muscle
a. calcium is not released from the sarcoplasmic reticulum
b. maximal force is never achieved
c. no force is produced unless the muscle shortens
d. maximal force is always achieved
a. calcium is not released from the sarcoplasmic reticulum
*b. maximal force is never achieved
c. no force is produced unless the muscle shortens
d. maximal force is always achieved
When a skeletal muscle is repetitively stimulated, twitches can overlap each other and result in a stronger muscle contraction than a stand-alone twitch. This phenomenon is known as
a. skeletal muscle tone (tonus)
b. the latent period
c. wave summation
d. fatigue
a. skeletal muscle tone (tonus)
b. the latent period
*c. wave summation
d. fatigue
Wave summation is achieved by
a. Increasing the stimulus frequency
b. decreasing stimulus frequency
c. adding AP's together so that their depolarizing magnitude is greater
d. allowing the muscle to complete relax between stimuli
*a. Increasing the stimulus frequency
b. decreasing stimulus frequency
c. adding AP's together so that their depolarizing magnitude is greater
d. allowing the muscle to complete relax between stimuli
Wave summation increases the force produced in the muscle. Another way to increase the force produced by a muscle is to
a. Slow action potential propagation down the motor neurons that innervate the muscle
b. Block calcium release from the sarcoplasmic reticulum
c. Decrease the number of activated motor units
d. Increase the number of activated motor units
a. Slow action potential propagation down the motor neurons that innervate the muscle
b. Block calcium release from the sarcoplasmic reticulum
c. Decrease the number of activated motor units
*d. Increase the number of activated motor units
Was there any change in the force generated by the muscle during the second stimulated twitch?
a. Yes, the second twitch generated less muscle force
b. No, the second twitch was the same as the first
c. Yes, the second twitch generated more force
a. Yes, the second twitch generated less muscle force
b. No, the second twitch was the same as the first
*c. Yes, the second twitch generated more force
As the stimulus frequency increases, what will happen to the muscle force generated with each successive stimulus? Will there be a limit to this response?
As the stimulus frequency increases, the muscle force generated by each successive stimulus will
a. Increase. There will be no limit to this increase.
b. Increase. There will be a limit to this increase.
c. Remain the same
d. First increase and then decrease as the stimulus frequency becomes very high
a. Increase. There will be no limit to this increase.
b. Increase. There will be a limit to this increase.
c. Remain the same
*d. First increase and then decrease as the stimulus frequency becomes very high
Is the total muscle force generated by the higher frequency simulation greater than the force generated in previous simulations?
a. Yes
b. No, remains the same
c. No, it is less
*a. Yes
b. No, remains the same
c. No, it is less
In order to produce sustained muscle contractions with an active force value of 5.2 g, do you think you will need to increase the stimulus voltage?
Yes
Does the force generated by the muscle change with each additional stimulus?
As the stimulus frequency increased, the muscle tension generated by each successive stimulus
a. Also increased, and there was no limit to this increase
b. Also increased, and a limiting maximum value was observed
c. Remained the same
d. Always decreased
a. Also increased, and there was no limit to this increase
*b. Also increased, and a limiting maximum value was observed
c. Remained the same
d. Always decreased
Which of the following is not one of the ways that the body can increase the force produced by a skeletal muscle?
a. Recruitment of more motor units and thus activation of more muscle fibers
b. Application of high-frequency stimulation by a motor neuron
c. Maintenance of elevated intracellular calcium levels, thus inducing wave summation
d. Application of higher voltages to the whole muscle
a. Recruitment of more motor units and thus activation of more muscle fibers
b. Application of high-frequency stimulation by a motor neuron
c. Maintenance of elevated intracellular calcium levels, thus inducing wave summation
*d. Application of higher voltages to the whole muscle
When a muscle receives a stimulus frequency that causes non-overlapping twitches to follow each other closely in time such that the peak tension of each twitch rises in a stepwise fashion up to a plateau value, the result is known as
a. Frappe
b. Wave summation
c. Treppe
d. Motor unit recruitment
a. Frappe
b. Wave summation
*c. Treppe
d. Motor unit recruitment
In this experiment, the isolated skeletal muscle was repetitively stimulated such that individual twitches overlapped with each other and resulted in a stronger muscle contraction than a standalone twitch. This is known as
a. Skeletal muscle tone (tonus)
b. Treppe
c. Wave summation
d. Fatigue
a. Skeletal muscle tone (tonus)
b. Treppe
*c. Wave summation
d. Fatigue
Wave summation is achieved by
a. Increasing the rate of stimulus delivery to the muscle
b. Removing intracellular calcium faster between stimuli
c. Summating action potentials so that their depolarizing magnitude is greater
d. Allowing the skeletal muscle to completely relax between stimuli
*a. Increasing the rate of stimulus delivery to the muscle
b. Removing intracellular calcium faster between stimuli
c. Summating action potentials so that their depolarizing magnitude is greater
d. Allowing the skeletal muscle to completely relax between stimuli
Stimulus frequency refers to the
a. Rate that the data tracings move across the oscilloscope screen
b. Rate that stimulating voltage pulses are applied to an isolated whole skeletal muscle
c. Rate of force development in stimulated twitches
d. Number of stimulating electrodes in contact with the isolated whole skeletal muscle
a. Rate that the data tracings move across the oscilloscope screen
*b. Rate that stimulating voltage pulses are applied to an isolated whole skeletal muscle
c. Rate of force development in stimulated twitches
d. Number of stimulating electrodes in contact with the isolated whole skeletal muscle
Which of the following distinguishes a state of unfused tetanus from a state of complete (fused) tetanus?
a. Rate of stimulus delivery is greater during a state of unfused tetanus
b. Muscle tension that develops is greater during a state of unfused tetanus
c. Muscle tension oscillates between different values during a state of complete tetanus
d. Muscle tension increases and decreases during a state of unfused tetanus
a. Rate of stimulus delivery is greater during a state of unfused tetanus
b. Muscle tension that develops is greater during a state of unfused tetanus
c. Muscle tension oscillates between different values during a state of complete tetanus
*d. Muscle tension increases and decreases during a state of unfused tetanus
When the stimulus frequency reaches a value beyond which no further increases in force are generated by the muscle, the muscle has reached its
a. Maximal tetenic tension
b. Threshold voltage
c. Unfused tetanic tension
d. Latent period
*a. Maximal tetenic tension
b. Threshold voltage
c. Unfused tetanic tension
d. Latent period
As the stimulus frequency increases further, what will happen to the muscle tension and twitch appearance with each successive stimulus. Will there be a limit to this response?
As the stimulus frequency increases, the muscle tension generated by each successive stimulus will
a. Increase. There will be no limit to this increase
b. Increase. There will be a limit
c. Remain the same
d. First increase and then decrease as the stimulus frequency becomes very high
a. Increase. There will be no limit to this increase
*b. Increase. There will be a limit
c. Remain the same
d. First increase and then decrease as the stimulus frequency becomes very high
How does the trace at 130 stimuli / s compare with the trace at 50 stimuli / s?
a. Summation of force ceases at this greater stimulus frequency
b. Fused tetanus develops at this greater stimulus frequency
c. Unfused tetanus fails to develop at this greater stimulus frequency
d. Maximum titanic sinking occurs
a. Summation of force ceases at this greater stimulus frequency
*b. Fused tetanus develops at this greater stimulus frequency
c. Unfused tetanus fails to develop at this greater stimulus frequency
d. Maximum titanic sinking occurs
How do the traces with 146-150 stimuli / s compare with the trace at 130 stimuli / s?
a. Summation of force ceases with these very high stimulation frequencies
b. Fused tetanus ceases with these very high stimulation frequencies
c. Unfused tetanus returns with these very high stimulation frequencies
d. Maximal tetanic tension develops with these very high stimulation frequencies
a. Summation of force ceases with these very high stimulation frequencies
b. Fused tetanus ceases with these very high stimulation frequencies
c. Unfused tetanus returns with these very high stimulation frequencies
*d. Maximal tetanic tension develops with these very high stimulation frequencies
The term tetanus refers to
a. The contractile response of a muscle to 1 AP
b. Sustained muscle tension due to very frequent stimuli
c. Sustained muscle tension due to a single stimulus
d. 1 Simultaneous twitch of all the fibers contained within the muscle
a. The contractile response of a muscle to 1 AP
*b. Sustained muscle tension due to very frequent stimuli
c. Sustained muscle tension due to a single stimulus
d. 1 Simultaneous twitch of all the fibers contained within the muscle
Which of the following distinguishes a state of unfused tetanus from a state of fused tetanus?
a. The rate of stimulus delivery is greater during a state of unfused tetanus
b. The muscle tension that develops is greater during a state of unfused tetanus
c. Muscle tension oscillates between different values for fused tetanus
d. Muscle tension increases and decreases between different values for unfused tetanus
a. The rate of stimulus delivery is greater during a state of unfused tetanus
b. The muscle tension that develops is greater during a state of unfused tetanus
c. Muscle tension oscillates between different values for fused tetanus
*d. Muscle tension increases and decreases between different values for unfused tetanus
When the stimulus frequency reaches a value beyond which no further increases in force are generated by the muscle, the muscle has reached its
a. Maximal tetanic tension
b. Threshold voltage
c. Unfused tetanic tension
d. Latent period
*a. Maximal tetanic tension
b. Threshold voltage
c. Unfused tetanic tension
d. Latent period
When skeletal muscle twitches fuse so that the peaks and valleys of each twitch become indistinguishable from each other, the muscle is in a state known as
a. Treppe
b. Unfused tetanus
c. Ultimate summation
d. Complete (fused) tetanus
a. Treppe
b. Unfused tetanus
c. Ultimate summation
*d. Complete (fused) tetanus
When the stimulus frequency reaches a value beyond which no further increase of skeletal muscle force can occur, the muscle has reached its
a. Rigor limit
b. Maximal tendon limit
c. Maximal tetanic tension
d. Energy consumption limit
a. Rigor limit
b. Maximal tendon limit
*c. Maximal tetanic tension
d. Energy consumption limit
A decline in a muscle's ability to maintain a constant level of force, or tension, after prolonged, repetitive stimulation is called
a. Tetanus
b. Summation
c. Fatigue
d. Rigor mortis
a. Tetanus
b. Summation
*c. Fatigue
d. Rigor mortis
Which of the following is not thought to be a contributing factor to the development of fatigue?
Buildup of ____ in the muscle fibers
a. Ca²⁺
b. Lactic acid
c. ADP
d. P_i
*a. Ca²⁺
b. Lactic acid
c. ADP
d. P_i
Why does the stimulated muscle force begin to decrease over time despite the maintained stimuli?
a. Intracellular acid is accumulating
b. Intracellular ADP and P_i are accumulating
c. Intracellular calcium movement is impaired
d. More than one of these answers could be correct
a. Intracellular acid is accumulating
b. Intracellular ADP and P_i are accumulating
c. Intracellular calcium movement is impaired
*d. More than one of these answers could be correct
Decrease in maximal force indicates developing
muscle fatigue
If the stimulator is briefly turned off for defined periods of time, what will happen to the length of time that the muscle is able to sustain maximal developed tension when the stimulator is turned on again?
The length of the rest period will _____ the length of time for sustained muscle tension.
a. Not substantially impact
b. Proportionately increase
c. Proportionately decrease
a. Not substantially impact
*b. Proportionately increase
c. Proportionately decrease
Why did the length of the intervening rest period affect the length of time the skeletal muscle can maintain maximum tension once the stimulator is turned again?
a. Intracellular concentrations of lactic acid increased
b. Intracellular concentration of ACh increased
c. Intracellular concentrations of ADP + P_i declined
d. Calcium levels in the sarcoplasmic reticulm declined
a. Intracellular concentrations of lactic acid increased
b. Intracellular concentration of ACh increased
*c. Intracellular concentrations of ADP + P_i declined
d. Calcium levels in the sarcoplasmic reticulm declined
During cross-bridge cycling in skeletal muscle, force is created by the power stroke of the _____
a. Tropomyosin molecules
b. Actin molecules
c. Myosin heads
d. Troponin molecules
a. Tropomyosin molecules
b. Actin molecules
*c. Myosin heads
d. Troponin molecules
The term tetanus refers to
a. Contractile response of a muscle to 1 AP
b. Sustained muscle tension due to repetitive stimuli
c. Sustained muscle tension due to a single stimulus
d. One twitch within the muscle
a. Contractile response of a muscle to 1 AP
*b. Sustained muscle tension due to repetitive stimuli
c. Sustained muscle tension due to a single stimulus
d. One twitch within the muscle
A decline in a muscle's ability to maintain a constant level of force, or tension, after prolonged, repetitive stimulation is called
a. Tetanus
b. Summation
c. Fatigue
d. Rigor mortis
a. Tetanus
b. Summation
*c. Fatigue
d. Rigor mortis
During fatigue
a. Myosin heads become locked with the thin, actin filament
b. Muscles go from a state of unfused tetanus to a state of fused tetanus
c. The number of active cross-bridges begins to decline although the rate of stimulus delivery remains constant
d. Intracellular calcium becomes depleted, therefore cross-bridges cannot cycle any longer
a. Myosin heads become locked with the thin, actin filament
b. Muscles go from a state of unfused tetanus to a state of fused tetanus
*c. The number of active cross-bridges begins to decline although the rate of stimulus delivery remains constant
d. Intracellular calcium becomes depleted, therefore cross-bridges cannot cycle any longer
If an intervening rest period is imposed on active skeletal muscle, the
a. Development of fatigue will be prevented
b. Stimulus frequency will fatigue
c. Development of fatigue will be delayed
d. Muscle will become refractory to subsequent stimulation
a. Development of fatigue will be prevented
b. Stimulus frequency will fatigue
*c. Development of fatigue will be delayed
d. Muscle will become refractory to subsequent stimulation
During an isometric contraction
a. The force generated by the skeletal muscle is greater than the load it is moving
b. Skeletal muscles undergo the sliding filament mechanism, which causes them to shorten
c. There is no active contraction within the skeletal muscle
d. The skeletal muscle is generating force but it remains at a fixed length
a. The force generated by the skeletal muscle is greater than the load it is moving
b. Skeletal muscles undergo the sliding filament mechanism, which causes them to shorten
c. There is no active contraction within the skeletal muscle
*d. The skeletal muscle is generating force but it remains at a fixed length
The force that results from muscles being stretched is
a. Passive force
b. Active force
c. Total force
d. Tetanic force
*a. Passive force
b. Active force
c. Total force
d. Tetanic force
Active force
a. Is determined by the weight of the load that the muscle is trying to move
b. Is determined by the amount of myosin bound to actin
c. Equals total force
d. Is greatest when muscles are stimulated at short lengths
a. Is determined by the weight of the load that the muscle is trying to move
*b. Is determined by the amount of myosin bound to actin
c. Equals total force
d. Is greatest when muscles are stimulated at short lengths
When you generate the isometric length-tension curve, which of the following forces will not be indicated on your screen?
_______ force
a. Total
b. Active
c. Tetanic
d. Passive
a. Total
b. Active
*c. Tetanic
d. Passive
Passive force in skeletal muscle is largely caused by
a. Actin thin filaments
b. Myosin thick filaments
c. The protein titin
d. Bungee cords
a. Actin thin filaments
b. Myosin thick filaments
*c. The protein titin
d. Bungee cords
As the resting length of the muscle is changed, what will happen to the amount of total force the muscle generates during the stimulated twitch?
a. An increase in muscle length will increase total force
b. A decrease in muscle length will decrease total force
c. Total force can increase or decrease depending upon the starting resting length
d. An increase in muscle length will decrease the total force
a. An increase in muscle length will increase total force
b. A decrease in muscle length will decrease total force
*c. Total force can increase or decrease depending upon the starting resting length
d. An increase in muscle length will decrease the total force
Note the dip in total force at a muscle length of 90 mm as compared to the total force at a muscle length of 80 and 100 mm. Why does this occur?
At this muscle length
a. There is too much overlap of myosin & actin, which impairs active force production
b. Titin is stretched beyond its natural limits, which impairs active force production
c. Passive force is the dominant value in the total force equation
d. Active force has decreased in value and passive force has not yet increased to a significant value
a. There is too much overlap of myosin & actin, which impairs active force production
b. Titin is stretched beyond its natural limits, which impairs active force production
c. Passive force is the dominant value in the total force equation
*d. Active force has decreased in value and passive force has not yet increased to a significant value
When a skeletal muscle is stimulated and generates force but remains at a fixed elngth
a. The muscle is contracting isotonically
b. There is insufficient electrical stimulation to move the load
c. There is no active force developed within the muscle
d. The muscle is contracting isometrically
a. The muscle is contracting isotonically
b. There is insufficient electrical stimulation to move the load
c. There is no active force developed within the muscle
*d. The muscle is contracting isometrically
Which protein is mostly responsible for the development of passive force in a muscle?
a. Actin
b. Myosin
c. Troponin
d. Titin
a. Actin
b. Myosin
c. Troponin
*d. Titin
In skeletal muscle, active force stimulated through a range of muscle lengths will
a. Be heavily influenced by the mass of the muscle being studied
b. Utilize ATP hydrolysis to drive the cross-bridge cycle
c. Always be the dominant value contributing to the total force of the muscle
d. Depend on the load attached to the free end of the muscle
a. Be heavily influenced by the mass of the muscle being studied
*b. Utilize ATP hydrolysis to drive the cross-bridge cycle
c. Always be the dominant value contributing to the total force of the muscle
d. Depend on the load attached to the free end of the muscle
Which of the following is not depicted in a typical skeletal muscle isometric length-tension curve?
a. Time
b. Active force
c. Total force
d. Passive force
*a. Time
b. Active force
c. Total force
d. Passive force
Maximal active tension will be produced in a skeletal muscle fiber when the fiber is
a. At its resting length
b. Is shorter than its resting length
c. Is longer than its resting length
d. Is at any length because tension is not dependent on muscle length
*a. At its resting length
b. Is shorter than its resting length
c. Is longer than its resting length
d. Is at any length because tension is not dependent on muscle length
During an isotonic contraction, the force generated by the muscle is _______ the weight of the attached load.
a. Less than
b. Greater than
c. Equal to
a. Less than
*b. Greater than
c. Equal to
During an isotonic contraction the latent period
a. Decreases with heavier loads
b. Increases with heavier loads
c. Is always the same regardless of the load
a. Decreases with heavier loads
*b. Increases with heavier loads
c. Is always the same regardless of the load
During the latent period for an isotonic contraction
a. There is no development of muscle force
b. The sliding filament mechanism causes the muscle to shorten
c. Cross-bridges cycle and, when muscle tension exceeds the load, muscle shortening occurs
d. Calcium remains stored inside the sarcoplasmic reticulum
a. There is no development of muscle force
b. The sliding filament mechanism causes the muscle to shorten
*c. Cross-bridges cycle and, when muscle tension exceeds the load, muscle shortening occurs
d. Calcium remains stored inside the sarcoplasmic reticulum
Muscle shortening velocity
a. Decreases with heavier loads
b. Increases with heavier loads
c. Decreases with lighter loads
d. Is constant regardless of the load
*a. Decreases with heavier loads
b. Increases with heavier loads
c. Decreases with lighter loads
d. Is constant regardless of the load
An isotonic contraction of a muscle is one in which
a. The length of the muscle changes
b. The length of the muscle stays the same
c. The muscle tension increases, but the muscle cannot lift the load
d. Muscle shortening velocity equals zero
*a. The length of the muscle changes
b. The length of the muscle stays the same
c. The muscle tension increases, but the muscle cannot lift the load
d. Muscle shortening velocity equals zero
As the load on the muscle increases, what will happen to the latent period, the shortening velocity, the distance that the weight moves, and the contraction duration?
Latent period: increase
Shortening velocity: decrease
Distance: decrease
Contraction duration: decrease
What kind of contraction did you observe when you attached the 2.0 g weight to the skeletal muscle and stimulated a contraction?
Isometric
Which of the weights allowed the fastest muscle shortening velocity?
The lightest
Which of the weights induced the longest latent period of the muscle contraction?
The heaviest weight that allowed isotonic contraction
Which weight did the muscle contraction move the greatest distance
the lightest
Which weight allowed the longest duration of muscle contraction
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