EX2

Which of the following terms are NOT used interchangeably? 1)
A) muscle tension — muscle force B) motor unit — motor neuron
C) in vivo — in the body D) muscle cell — muscle fiber

motor unit — motor neuron

Which of the following is NOT a phase of a muscle twitch? 2)
A) latent period B) relaxation phase
C) contraction phase D) shortening phase

shortening phase

Where does the acetylcholine released for muscle contraction bind? 3)
A) receptors in the axon terminal B) receptors in the motor end plate
C) receptors in the sarcoplasmic reticulum D) receptors in troponin

receptors in the motor end plate

When acetylcholine binds to its receptors, it results in __________. 4)
A) the end plate potential
B) a change in ion permeability
C) the end plate potential, a graded depolarization, and a change in ion permeability
D) a graded depolarization

the end plate potential, a graded depolarization, and a change in ion permeability

Which of the following occurs during the latent period of muscle contraction? 5)
A) An action potential is generated.
B) Calcium is released from the sarcoplasmic reticulum.
C) Acetylcholine is released at the axon terminal and an action potential is generated.
D) Acetylcholine is released at the axon terminal

Calcium is released from the sarcoplasmic reticulum.

As the stimulus voltage was increased in this activity, which of the following occurred? 6)
A) The muscle force generated decreased. B) The muscle force generated increased.
C) The latent period decreased in length. D) The latent period increased in length

The muscle force generated increased.

Which of the following describes the relaxation phase? 7)
A) The sarcomeres are decreasing in length, and the force generated increases.
B) The sarcomeres are increasing in length, and the force generated decreases.
C) The sarcomeres are decreasing in length, and the force generated decreases.
D) The sarcomeres are increasing in length, and the force generated increases.

The sarcomeres are decreasing in length, and the force generated decreases.

Which of the following can trigger a muscle twitch? 8)
A) electrical stimulation
B) release of calcium from the sarcolemma
C) release of acetylcholine and release of calcium from the sarcolemma
D) release of acetylcholine and electrical stimulation
E) release of acetylcholine

release of acetylcholine and electrical stimulation

Which of the following is proportional to the amount of tension produced by a skeletal muscle? 9)
A) the length of the latent period B) the length of the relaxation phase
C) the number of motor units activated D) the threshold voltage

the number of motor units activated

NO force is generated during which of the following? 10)
A) a muscle twitch B) the relaxation phase
C) the contraction phase D) the latent period

) the latent period

What is the minimum voltage needed to generate muscle contraction? 11)
A) stimulus voltage B) contraction voltage
C) recruitment voltage D) threshold voltage

threshold voltage

A motor unit is defined as _______. 12)
A) a nerve and a muscle
B) the axon terminals of a single motor neuron and all of the muscle fibers that it stimulates
C) a single neuron and a single muscle fiber
D) a single muscle fiber and all its axon terminals

the axon terminals of a single motor neuron and all of the muscle fibers that it stimulates

In the lab, a researcher finds that the threshold stimulus to induce an action potential in a muscle
fiber’s sarcolemma was 3.0 volts. Which of the following would result in muscle tension?
13)
A) 1.0 volt
B) 3.0 volts and 4.0 volts
C) 2.0 volts
D) 3.0 volts
E) 4.0 volts

3.0 volts and 4.0 volts

Increasing the applied voltage in the simulation corresponds to which in vivo event? 14)
A) muscle twitch recruitment B) motor unit recruitment
C) muscle fiber recruitment D) motor neuron recruitment

motor unit recruitment

As the stimulus voltage increased, the resulting muscle tension _______. 15)
A) remained the same
B) increased to a point until it reached a plateau
C) increased proportionally
D) decreased proportionally

increased to a point until it reached a plateau

Which of the following is occurring during the contraction phase? 16)
A) Cross-bridge cycling is taking place.
B) Calcium is released from the sarcoplasmic reticulum.
C) Acetylcholine binds to the sarcolemma.
D) The sarcomeres are increasing in length.

Cross-bridge cycling is taking place

Treppe is the phenomenon that results in _______. 17)
A) a progressive increase in the force generated with repetitive stimulation
B) motor unit recruitment
C) an increase in the stimulation frequency
D) maximal force production by a skeletal muscle

a progressive increase in the force generated with repetitive stimulation

When the frequency of stimulation of a muscle is great enough, _______. 18)
A) wave summation results
B) full relaxation of the muscle occurs and wave summation results
C) full relaxation of the muscle occurs
D) wave summation results and muscle twitches overlap
E) muscle twitches overlap

wave summation results and muscle twitches overlap

When wave summation occurs, _______. 19)
A) individual muscle twitches are separated
B) the muscle fiber has received a single stimulus event
C) the muscle force generated decreases
D) the muscle force generated increases

the muscle force generated increases

Why does wave summation occur? 20)
A) A large amount of time elapses between stimulations.
B) Muscle fibers have been allowed to fully relax.
C) Muscle fibers are partially contracted when the next stimulus arrives.
D) Muscle twitches are not yet overlapping

Muscle fibers are partially contracted when the next stimulus arrives.

Which of the following produced an increase in stimulus intensity? 21)
A) clicking the mouse in rapid succession
B) increasing the voltage applied
C) clicking the mouse in rapid succession and allowing the muscle to completely relax in
between contractions
D) allowing the muscle to completely relax in between contractions

increasing the voltage applied

Which of the following produced an increase in stimulus frequency? 22)
A) allowing the muscle to completely relax between contractions
B) clicking the mouse in rapid succession
C) clicking the mouse in rapid succession and allowing the muscle to completely relax in
between contractions
D) increasing the voltage applied

clicking the mouse in rapid succession

Which of the following does NOT describe treppe? 23)
A) An incremental increase in force occurs.
B) A period of relaxation can be seen on the muscle twitch tracing.
C) It is also referred to as the "staircase" effect.
D) An increase in stimulus intensity is required to see the effect

An increase in stimulus intensity is required to see the effect

Which of the following describes how you were able to achieve an active force of 5.2 g? 24)
A) by applying multiple stimuli at 10 volts B) by applying multiple stimuli at 12 volts
C) by applying multiple stimuli at 8.5 volts D) by applying a single stimulus at 8.5 volts

by applying multiple stimuli at 10 volts

Which of the following does NOT describe tetanus? 25)
A) The muscle relaxes fully between contractions.
B) The maximum force produced has reached a plateau.
C) It can be fused.
D) It can be unfused.

The muscle relaxes fully between contractions.

Which of the following is true of the maximum stimulus frequency? 26)
A) Muscle force will decrease.
B) Muscle has reached maximal tetanic tension.
C) No greater muscle force can be generated and the muscle has reached maximal tetanic
tension.
D) No greater muscle force can be generated and muscle force will decrease.
E) No greater muscle force can be generated.

No greater muscle force can be generated and the muscle has reached maximal tetanic tension.

Muscle twitches overlap with _______. 27)
A) unfused tetanus only B) threshold voltage applied
C) both fused and unfused tetanus D) fused tetanus only

both fused and unfused tetanus

Which of the following would result in fused or unfused tetanus? 28)
A) increasing the stimulus frequency
B) threshold stimulus and single stimuli
C) decreasing the stimulus frequency
D) decreasing the stimulus frequency or increasing the stimulus frequency

increasing the stimulus frequency

To transition from unfused tetanus to fused tetanus, _______. 29)
A) the muscle fibers were allowed to relax B) wave summation was not allowed
C) stimulus frequency decreased D) stimulus frequency increased

stimulus frequency increased

Which of the following describes the relationship between stimulus frequency and muscle tension? 30)
A) When stimulus frequency increases, muscle tension increases indefinitely.
B) When stimulus frequency decreases, muscle tension increases indefinitely.
C) When stimulus frequency increases, muscle tension increases to a maximum value.
D) When stimulus frequency increases, muscle tension decreases.

When stimulus frequency increases, muscle tension increases to a maximum value.

At what stimulus frequency was maximal tetanic tension developed? 31)
A) 50 stimuli/sec B) 146 stimuli/sec C) 140 stimuli/sec D) 130 stimuli/sec

146 stimuli/se

Which of the following is matched correctly? 32)
A) complete tetanus — fused tetanus B) complete tetanus — unfused tetanus
C) incomplete tetanus — fatigue D) incomplete tetanus — fused tetanus

complete tetanus — fused tetanus

Which of the following does NOT lead to muscle fatigue? 33)
A) maximal tetanic tension B) prolonged muscle contraction
C) high-intensity exercise of a long duration D) repetitive stimulation of a muscle

maximal tetanic tension

Which of the following molecules is NOT thought to accumulate during muscle fatigue? 34)
A) inorganic phosphate B) ATP
C) ADP D) lactic acid

ATP

During muscle fatigue, the ____________ decreases. 35)
A) number of muscle fibers B) force of contraction
C) stimulus frequency D) rest period

force of contraction

In this activity, why did the muscle force decrease over time? 36)
A) Muscle fatigue developed.
B) The stimulation frequency was increased.
C) Intracellular calcium built up.
D) The stimulation frequency was decreased.

Muscle fatigue developed.

Which of the following describes how increasing the duration of the rest period affected muscle
tension?
37)
A) Increasing the duration of the rest period increased muscle tension.
B) Decreasing the duration of the rest period increased muscle tension.
C) Decreasing the duration of the rest period decreased muscle tension.
D) Increasing the duration of the rest period decreased muscle tension.

Increasing the duration of the rest period increased muscle tension.

What might be occurring on a molecular level during the rest periods? 38)
A) Intracellular calcium is decreasing.
B) Muscle fatigue is increasing.
C) Intracellular ADP and inorganic phosphate are decreasing.
D) Intracellular lactic acid is increasing.

Intracellular ADP and inorganic phosphate are decreasing.

Which of the following occurs if the load attempted is equal to or greater than the force generated
by a muscle?
39)
A) Isotonic muscle contraction occurs. B) The muscle lengthens.
C) The muscle shortens. D) Isometric muscle contraction occurs.

Isometric muscle contraction occurs.

The resting length of the muscle _______. 40)
A) describes the length of the muscle during contraction.
B) occurs when the muscle is relaxed.
C) occurs when peak tension develops.
D) describes the muscle during stimulation.

occurs when the muscle is relaxed.

The graph of the length-tension relationship illustrates _______. 41)
A) the relationship between muscle diameter and tension and the optimal sarcomere length for
muscle contraction
B) the optimal sarcomere length for muscle contraction
C) the amount of overlap between the thick and thin filaments in the resting muscle
D) the optimal sarcomere length for muscle contraction and the amount of overlap between the
thick and thin filaments in the resting muscle
E) the relationship between muscle diameter and tension

the optimal sarcomere length for muscle contraction and the amount of overlap between the thick and thin filaments in the resting muscle

Which of the following is generated when cross-bridges form between actin and myosin? 42)
A) ATP
B) active force and passive force
C) passive force
D) active force and ATP
E) active force

active force

Which of the following describes the relationship between length and tension? 43)
A) As the muscle’s resting length increases, the active force will decrease.
B) As the muscle’s resting length decreases, the active force will decrease.
C) As the muscle’s resting length increases, the active force will increase.
D) The active force can increase or decrease, depending on the starting resting length of the
muscle.

The active force can increase or decrease, depending on the starting resting length of the muscle.

Why does the active force of skeletal muscle change with the muscle’s resting length? 44)
A) The amount of resistance varies.
B) The amount of available calcium varies.
C) The number of cross-bridges between actin and myosin varies.
D) The amount of available ATP varies

The number of cross-bridges between actin and myosin varies

Which starting length of the muscle provided the maximum total force? 45)
A) the longest starting length
B) the shortest starting length
C) an intermediate starting length
D) The length of the muscle did not affect the amount of total force produced.

an intermediate starting length

At which muscle length was the passive force the greatest? 46)
A) 80 mm B) 70 mm C) 90 mm D) 100 mm

100 mm

Which of the following occurs during isotonic concentric contraction? 47)
A) The length of the muscle increases with contraction.
B) The length of the muscle stays the same.
C) The length of the muscle increases and decreases with contraction.
D) The length of the muscle decreases with contraction.

The length of the muscle decreases with contraction.

Which of the following occurs during the latent period of isotonic concentric contraction? 48)
A) Muscle tension is not produced, and the weight will move.
B) Muscle tension is produced, and the weight will not move.
C) Muscle tension is produced, and the weight will move.
D) Muscle tension is not produced, and the weight will not move

Muscle tension is produced, and the weight will not move.

The speed of muscle contraction is called the _______. 49)
A) contraction velocity B) twitch velocity
C) shortening velocity D) isometric velocity

shortening velocity

For a weight to be lifted, which of the following must occur? 50)
A) isotonic muscle contraction with a force less than the load
B) isometric muscle contraction with a force greater than the load
C) isotonic muscle contraction with a force greater than the load
D) either isometric or isotonic muscle contraction with a force greater than the load
E) either isotonic muscle contraction with a force greater than the load or a force less than the
load

isotonic muscle contraction with a force greater than the load

When the load to be lifted increases in weight, the latent period _______. 51)
A) decreases and disappears B) increases
C) remains unchanged D) decreases

increases

The shortest duration of muscle contraction occurs with _______. 52)
A) the intermediate load
B) the heaviest load
C) the lightest load
D) The duration of muscle contraction doesn’t vary with the load lifted.

the heaviest load

The velocity of shortening _______. 53)
A) decreased as the weight increased and increased as the weight decreased
B) decreased as the weight increased
C) increased as the weight decreased
D) increased as the weight increased

decreased as the weight increased and increased as the weight decreased

As the weight increased, the distance the weight was lifted _______. 54)
A) increased
B) did not change
C) decreased
D) decreased until the weight was not moved at all

decreased until the weight was not moved at all