Question 1

Atrophy at the neuromuscular junction that naturally occurs with age would have what effect on muscles?

Accepted Answer

A)   It would stimulate the nervous system to increase the speed in which it sends action potentials to the muscle fiber.
B)   It would stimulate muscle cramps.
C)   It would decrease the number of action potentials sent to the muscle fiber.
D)   It would cause an increase in the amount of ACh released by the neurons to compensate.
E)   It would have no effect on the muscles.F) A) and E)
G) A) and B)

Question 2

Which of the following is NOT a property of the myosin head?

Accepted Answer

A)   They form cross-bridges with the active sites of actin.
B)   They have a hinge region to bend and straighten.
C)   They bind to troponin.
D)   They have ATPase activity.
E)   They bind to ATP.F) A) and E)
G) A) and B)

Question 3

Why does muscle activity affect the temperature of the body?

Accepted Answer

A)   The rate of chemical reactions increases in muscle fibers during contraction, so the rate of heat production also increases.
B)   Muscle contraction generates pyrogens which reset the body's internal thermostat to a higher temperature.
C)   Muscle activity directs more warm blood to the muscles away from the central core causing a cooling effect on your internal organs.
D)   Increased muscle activity causes a rise in adipose stores which increases the insulation value of the body.E) None of the above
F) A) and D)

Question 4

What is tropomyosin?

Accepted Answer

A)   A protein found along the groove of the F-actin double helix
B)   A T tubule and two adjacent terminal cisternae
C)   The combination of myosin heads with active sites on actin molecules
D)   The movement of myosin head while attached to actin myofilament
E)   After exercise, the O2 taken in that exceeds the O2 required for resting metabolismF) A) and B)
G) C) and D)

Question 5

The type of muscle fatigue known as "psychological fatigue" is the result of

Accepted Answer

A)   depleted ATP reserves.
B)   increased Ca2+ concentration in the sarcoplasm.
C)   decreased levels of acetylcholine.
D)   the emotional state of an individual.
E)   None of these choices are correct.F) A) and B)
G) A) and C)

Question 6

If Na+ cannot enter a muscle fiber in response to a stimulus,

Accepted Answer

A)   contraction cannot occur.
B)   relaxation cannot occur.
C)   Na+ will be released from the sarcoplasmic reticulum instead.
D)   the active sites are left exposed.
E)   the action potential travels into the muscle anyway.F) D) and E)
G) None of the above

Question 7

Channels that open or close in response to changes in the electrical charge or voltage across the plasma membrane are called

Accepted Answer

A)   ligand-gated ion channels.
B)   leak ion channels.
C)   relegated ion channels.
D)   voltage-gated ion channels.
E)   obligated ion channels.F) None of the above
G) C) and E)

Question 8

Which of the following is composed of myosin molecules?

Accepted Answer

A)   Thick myofilaments
B)   I bands
C)   Z disks
D)   Sarcolemma
E)   TropomyosinF) C) and E)
G) B) and D)

Question 9

Which of the following is part of a thin myofilament?

Accepted Answer

A)   ATP-binding site
B)   Globular (G)  actin
C)   Calcium
D)   Myosin
E)   SarcolemmaF) A) and B)
G) None of the above

Question 10

When the myosin head flexes into a bend, pulling the actin filament along with it, this is called the

Accepted Answer

A)   action reaction.
B)   power stroke.
C)   recovery stroke.
D)   muscle tone.
E)   action potential.F) All of the above
G) A) and B)

Question 11

Which of the following is NOT a function of skeletal muscle?

Accepted Answer

A)   Body movement
B)   Maintenance of posture
C)   Respiration
D)   Constriction of organs
E)   Production of heatF) B) and D)
G) All of the above

Question 12

Actin myofilaments

Accepted Answer

A)   resemble bundles of minute golf clubs.
B)   contain both myosin and tropomyosin.
C)   are held in place by the M line.
D)   contain strands of fibrous actin.
E)   are the thickest proteins in muscle.F) B) and C)
G) B) and D)

Question 13

When repolarization of the plasma membrane is complete, the

Accepted Answer

A)   cell dies.
B)   cell regenerates.
C)   cell no longer has a potential difference across its membrane.
D)   cell is no longer responsive.
E)   original polarity of the cell is restored.F) D) and E)
G) B) and D)

Question 14

Concentric contractions occur when

Accepted Answer

A)   the muscle produces increasing tension as it shortens.
B)   the tension and length of the muscle remain constant during a contraction.
C)   tension in a muscle is maintained while the muscle increases in length.
D)   the muscle produces tension while the length of the muscle increases.
E)   isometric contractions occur.F) A) and B)
G) B) and D)

Question 15

Endomysium is a delicate network of loose connective tissue that

Accepted Answer

A)   surrounds each muscle fiber.
B)   forms a sheath around a fascicle.
C)   is composed of elastic fibers.
D)   separates individual muscles.
E)   penetrates muscle fibers.F) C) and E)
G) B) and C)

Question 16

-What does "A" represent on the diagram?

Accepted Answer

A)   Threshold
B)   Depolarization
C)   Depolarization phase of action potential
D)   Repolarization phase of action potentialE) All of the above
F) A) and D)

Question 17

Myosin phosphatase

Accepted Answer

A)   activates myosin kinase.
B)   forms the cross-bridge.
C)   removes phosphate from myosin.
D)   binds to calcium-calmodulin complex.
E)   opens Ca2+-channels.F) A) and D)
G) B) and D)

Question 18

Which of the following will respond to a threshold stimulus with an all-or-none contraction?

Accepted Answer

A)   A single muscle fiber
B)   A single motor unit
C)   A whole muscle
D)   Both a single muscle fiber and a single motor unit are correct.
E)   A single muscle fiber, a single motor unit, and a whole muscle are all correct.F) C) and D)
G) None of the above

Question 19

Substance A is found to be a competitor with acetylcholine. Which step of muscle contraction physiology would be directly affected by this substance?

Accepted Answer

A)   Exposure of the active sites on G actin
B)   Release of acetylcholine from the presynaptic terminal
C)   Generation of an action potential at the sarcolemma
D)   Release of the myosin head following the power strokeE) A) and B)
F) B) and D)

Question 20

As muscle activity increases, the body temperature ________.

Accepted Answer

A)   decreases
B)   increasesC) A) and B)
D) undefined

Exam 9: Muscular System: Histology and Physiology

When the myosin head flexes into a bend, pulling the actin filament along with it, this is called the

Correct AnswerverifiedShow Answer

Substance A is found to be a competitor with acetylcholine. Which step of muscle contraction physiology would be directly affected by this substance?

Correct AnswerverifiedShow Answer

Atrophy at the neuromuscular junction that naturally occurs with age would have what effect on muscles?

Correct AnswerverifiedShow Answer

Why does muscle activity affect the temperature of the body?

Correct AnswerverifiedShow Answer

Which of the following is part of a thin myofilament?

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Which of the following is NOT a function of skeletal muscle?

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Actin myofilaments

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Myosin phosphatase

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Which of the following is NOT a property of the myosin head?

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As muscle activity increases, the body temperature ________.

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The type of muscle fatigue known as "psychological fatigue" is the result of

Correct AnswerverifiedShow Answer

When repolarization of the plasma membrane is complete, the

Correct AnswerverifiedShow Answer

Endomysium is a delicate network of loose connective tissue that

Correct AnswerverifiedShow Answer

Which of the following will respond to a threshold stimulus with an all-or-none contraction?

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Which of the following is composed of myosin molecules?

Correct AnswerverifiedShow Answer

Channels that open or close in response to changes in the electrical charge or voltage across the plasma membrane are called

Correct AnswerverifiedShow Answer

Concentric contractions occur when

Correct AnswerverifiedShow Answer

-What does "A" represent on the diagram?

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What is tropomyosin?

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If Na+ cannot enter a muscle fiber in response to a stimulus,

Correct AnswerverifiedShow Answer

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If Na⁺ cannot enter a muscle fiber in response to a stimulus,

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