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Physio > Physio Lab Homework > Flashcards

Physio Lab Homework Flashcards

1
Q

Skeletal muscles are connected to bones by

A

Tendons

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2
Q

Skeletal muscles are composed of hundreds to thousands of individual cells called?

A

Fibers

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3
Q

The term motor unit refers to

A

One motor neuron and all of the skeletal muscle fibers it innervates

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4
Q

The motor neuron and muscle fiber intersect at what is called

A

the neuromuscular junction

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5
Q

A twitch is

A

One contractile response to a single action potential

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6
Q

What is the period of time that elapses between the generation of an action potential and the start of muscle tension development in the muscle fiber?

A

The latent period

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7
Q

What occurs during the latent period of these isometric contractions?

A

All of the steps of excitation-contraction coupling occur

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8
Q

An action potential in the motor neuron triggers the release of which neurotransmitter?

A

Acetylcholine

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9
Q

The term skeletal muscle fiber refers to

A

an individual skeletal muscle cell

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10
Q

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 EPP (end-plate potential)

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11
Q

Which of the following is not a phase of skeletal muscle twitch?

A

hyperpolarization phase

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12
Q

Which of the following correctly matches the twitch phase with its definition?

A

The contraction phase: the time between the end of the latent period and peak muscle tension

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13
Q

Skeletal muscle fibers are innervated (stimulated) by

A

Motor neuron

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14
Q

A single action potential propagating down a motor axon results in

A

A single action potential and single contractile event in the muscle fibers it innervates

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15
Q

In resting skeletal muscle, calcium is stored in

A

The sarcoplasmic reticulum

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16
Q

During the latent period for an isometric contraction

A

the cellular events involved in the excitation-contraction coupling occur

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17
Q

What is the lowest stimulus voltage that induces active force in the skeletal muscle?

A

Threshold voltage

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18
Q

Motor unit recruitment refers to

A

an increase in the number of active muscle fibers to increase the force developed in the muscle.

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19
Q

Active tension (or force) in a skeletal muscle fiber results from

A

Activation of cross bridge cycling via increased intracellular calcium levels.

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20
Q

The (blank) is the minimal stimulus needed to cause depolarization of the muscle plasma membrane (sarcolemma)

A

Threshold voltage

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21
Q

By definition, the (blank) is the amount of stimulus required to successfully recruit ALL the muscle fibers into developing maximum force.

A

Maximal voltage

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22
Q

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

The electrical stimulus mimics acetylcholine release at the neuromuscular junction

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23
Q

During a single twitch of a skeletal muscle

A

Maximal force is never achieved

24
Q

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

Wave summation

25
Q

Wave summation is achieved by

A

Increasing the stimulus frequency (the rate of stimulus delivered to the muscle)

26
Q

Wave summation increased the force produced in the muscle. Another way to increase the force produced by a muscle is to

A

increase the number of activated motor units

27
Q

Which of the following is NOT one of the ways that the body can increase the force produced by a skeletal muscle?

A

Application of higher voltages to the whole muscle

28
Q

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 the stepwise fashion up to a plateau value, the result is known as

A

treppe

29
Q

Stimulus frequency refers to

A

The rate that stimulating voltage pulses are applied to an isolated whole skeletal muscle

30
Q

Which of the following distinguishes a state of unfused tetanus from a state of complete (fused) tetanus?

A

Muscle tension increases and decreases during a state on unfused tetanus

31
Q

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

32
Q

The term tension refers to

A

Sustained muscle tension due to very frequent stimuli

33
Q

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

Complete (fused) tetanus

34
Q

A decline in a muscle’s ability to maintain a constant level of force, or tension, after prolonged, repetitive stimulation is called

A

Fatigue

35
Q

Which of the following is not thought to be a contributing factor to the development of fatigue

A

Buildup of Ca2 in the muscle fibers

36
Q

When 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 on again?

A

Intercellular concentrations of ADP and Pi declined during the rest period

37
Q

During cross bridge cycling in skeletal muscle, force is created by the

A

power stroke of the myosin heads

38
Q

The term tetanus refers to

A

Sustained muscle tension due to repetitive stimuli

39
Q

During fatigue

A

the number of active cross bridges begins to decline although the rate of stimulus delivery (frequency) remains constant

40
Q

If an intervening rest period is imposed on active skeletal muscle

A

the development of fatigue will be delayed

41
Q

During isometric contraction

A

the skeletal muscle is generating force, but it remains at a fixed length

42
Q

The force that results from muscles being stretched is

A

passive force

43
Q

Active force

A

is determined by the amount of myosin bound to actin

44
Q

When you generate the isometric length-tension curve, which of the following forces will NOT be indicated?

A

tetanic force

45
Q

Passive force in skeletal muscle is largely caused by

A

the protein titin

46
Q

When skeletal muscle is stimulated and generates force but remains at a fixed length

A

the muscle is contracting isometrically

47
Q

in skeletal muscle, active force stimulated through a range of muscle lengths

A

will utilize ATP hydrolysis to drive the cross bridge cycle

48
Q

Which of the following is NOT depicted in a typical skeletal muscle isometric length-tension curve?

A

Time

49
Q

Maximal active tension will be produced in a skeletal muscle fiber when

A

the fiber is at its resting length

50
Q

During an isotonic concentric contraction, the

A

force generate by the muscle is greater than the weight of the attached load

51
Q

During an isotonic concentric contraction

A

the latent period increases with heavier loads

52
Q

During the latent period for an isotonic concentric contraction

A

cross bridges cycle and when muscle tension exceeds the load, muscle shortening occurs

53
Q

Muscle shortening velocity

A

decreases with heavier loads

54
Q

An isotonic contraction of a muscle is one in which

A

the length of the muscle changes

55
Q

When lifting a heavy load

A

the muscle shortening velocity is decreased in comparison with lighter loads

Physio (5 decks)

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