Question 1

Type IIx fibers

Accepted Answer

A)   contain a high concentration of aerobic enzymes.
B)   are very energy efficient.
C)   have high specific tension.
D)   exhibit a high level of fatigue resistance.

Question 2

The two principal contractile proteins found in skeletal muscle are

Accepted Answer

A)   actin and troponin.
B)   actin and myosin.
C)   troponin and tropomyosin.
D)   myosin and tropomyosin.

Question 3

Rigor mortis is caused by an inability of myosin to enter a weak binding state with actin.

Accepted Answer

A) True 
 B)False

Question 4

The formation of cross-bridges in the contractile process in skeletal muscle is

Accepted Answer

A)   potassium binding to myosin.
B)   calcium binding to tropomyosin.
C)   calcium binding to troponin.
D)   ATP binding to the myosin cross-bridges.

Question 5

If you continue to increase the firing rate (of action potentials) of a motor neuron, then all of the skeletal muscle fibers it innervates will eventually summate to tetanus.

Accepted Answer

A) True 
 B)False

Question 6

Which of the following events in muscle contraction is the first to occur chronologically?

Accepted Answer

A)   The T-tubules depolarize, causing calcium to be released from the sarcoplasmic reticulum.
B)   Calcium is resequestered (taken up)  into the sarcoplasmic reticulum.
C)   Tropomyosin moves, exposing the actin active sites.
D)   The innervating alpha-motor neuron has an action potential.
E)   The binding of acetylcholine causes a skeletal sarcolemma to have an action potential.

Question 7

Recent evidence suggests that rigorous exercise training can result in a conversion of muscle fiber type.

Accepted Answer

A) True 
 B)False

Question 8

Muscle atrophy may be caused by a decrease in protein production, as well as an increase in protein degradation.

Accepted Answer

A) True 
 B)False

Question 9

The change in muscle fiber type that would most likely occur as a result of endurance training is

Accepted Answer

A)   type I  →\rightarrow→  type II
B)   type IIx  →\rightarrow→  type IIa
C)   type IIa →\rightarrow→  type IIx
D)   type IIx  →\rightarrow→  type I

Question 10

The motor neuron and all the muscle fibers it innervates are called a motor

Accepted Answer

A)   junction.
B)   unit.
C)   end plate.
D)   nerve. B

Question 11

The site where the motor neuron and muscle cell meet is called the

Accepted Answer

A)   end-plate potential.
B)   motor unit.
C)   sarcolemma.
D)   neuromuscular junction.

Question 12

Tetanus is defined as the use of sufficient motor units to initiate movements.

Accepted Answer

A) True 
 B)False

Question 13

A successful endurance athlete would likely have ________________ compared to a sedentary person.

Accepted Answer

A)   a higher percentage of glycolytic fibers
B)   a higher percentage of type I fibers
C)   a higher percentage of fast-twitch fibers
D)   the same percentage of slow-twitch and fast-twitch fibers

Question 14

High activity of the enzyme ATPase is found in both slow-twitch and fast-twitch fibers.

Accepted Answer

A) True 
 B)False

Question 15

Fast-twitch fibers contain a relatively

Accepted Answer

A)   large number of mitochondria and low ATPase activity.
B)   small number of mitochondria and low ATPase activity.
C)   small number of mitochondria and high ATPase activity. C

Question 16

Which of the following has been shown to cause muscle fatigue?

Accepted Answer

A)   the accumulation H+
B)   the accumulation of ATP
C)   the accumulation of Na+
D)   the accumulation of muscle glycogen

Question 17

The amount of force exerted during muscular contraction is dependent on the

Accepted Answer

A)   type of motor units recruited and nothing else.
B)   type of motor units recruited, the initial length of the muscle, and the nature of the neural stimulation.
C)   length of the muscle fibers only.
D)   nature of the neural stimulation only.

Question 18

In contrast to power athletes, endurance athletes typically possess a low percentage of slow fibers and a high percentage of fast fibers.

Accepted Answer

A) True 
 B)False

Question 19

Which of the following events in muscle contraction is the last to occur chronologically?

Accepted Answer

A)   The T-tubules depolarize, causing calcium to be released from the sarcoplasmic reticulum.
B)   Calcium is resequestered (taken up)  into the sarcoplasmic reticulum.
C)   Tropomyosin moves, exposing the actin active sites.
D)   The innervating alpha-motor neuron has an action potential.
E)   The binding of acetylcholine causes a skeletal sarcolemma to have an action potential.

Question 20

Calcium is stored in muscle within the

Accepted Answer

A)   Golgi organs.
B)   H zone.
C)   sarcoplasmic reticulum.
D)   sarcolemma. C

Exam 9: Skeletal Muscle: Structure and Function

Type IIx fibers

Correct AnswerverifiedShow Answer

The two principal contractile proteins found in skeletal muscle are

Correct AnswerverifiedShow Answer

Rigor mortis is caused by an inability of myosin to enter a weak binding state with actin.

Correct AnswerverifiedShow Answer

The formation of cross-bridges in the contractile process in skeletal muscle is

Correct AnswerverifiedShow Answer

If you continue to increase the firing rate (of action potentials) of a motor neuron, then all of the skeletal muscle fibers it innervates will eventually summate to tetanus.

Correct AnswerverifiedShow Answer

Which of the following events in muscle contraction is the first to occur chronologically?

Correct AnswerverifiedShow Answer

Recent evidence suggests that rigorous exercise training can result in a conversion of muscle fiber type.

Correct AnswerverifiedShow Answer

Muscle atrophy may be caused by a decrease in protein production, as well as an increase in protein degradation.

Correct AnswerverifiedShow Answer

The change in muscle fiber type that would most likely occur as a result of endurance training is

Correct AnswerverifiedShow Answer

The motor neuron and all the muscle fibers it innervates are called a motor

Correct AnswerverifiedB

The site where the motor neuron and muscle cell meet is called the

Correct AnswerverifiedShow Answer

Tetanus is defined as the use of sufficient motor units to initiate movements.

Correct AnswerverifiedShow Answer

A successful endurance athlete would likely have ________________ compared to a sedentary person.

Correct AnswerverifiedShow Answer

High activity of the enzyme ATPase is found in both slow-twitch and fast-twitch fibers.

Correct AnswerverifiedShow Answer

Fast-twitch fibers contain a relatively

Correct AnswerverifiedC

Which of the following has been shown to cause muscle fatigue?

Correct AnswerverifiedShow Answer

The amount of force exerted during muscular contraction is dependent on the

Correct AnswerverifiedShow Answer

In contrast to power athletes, endurance athletes typically possess a low percentage of slow fibers and a high percentage of fast fibers.

Correct AnswerverifiedShow Answer

Which of the following events in muscle contraction is the last to occur chronologically?

Correct AnswerverifiedShow Answer

Calcium is stored in muscle within the

Correct AnswerverifiedC

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B

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C

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C