Question 1

Which of the following is NOT true of the latch state of smooth muscle contraction?

Accepted Answer

A)   Myosin phosphatase removes the phosphate group from myosin.
B)   It explains why smooth muscle can sustain tension for long periods of time.
C)   It occurs when the phosphate is removed while the cross-bridges are attached to actin.
D)   It occurs when the phosphate is removed while the cross-bridges are not attached to actin.
E)   It allows contraction without a large energy expenditure.F) A) and B)
G) B) and C)

Question 2

-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) A) and C)
F) B) and D)

Question 3

What are caveolae?

Accepted Answer

A)   can rapidly develop action potentials
B)   shallow invaginations of cell membrane
C)   relatively constant tension maintained for a period of time
D)   intracellular cytoskeleton
E)   enzyme that removes phosphate from myosinF) A) and E)
G) C) and D)

Question 4

-The figure illustrates a detailed drawing of the neuromuscular junction. What does "D" represent?

Accepted Answer

A)   synaptic vesicles
B)   synaptic cleft
C)   sarcolemma
D)   presynaptic terminal
E)   postsynaptic membraneF) A) and B)
G) B) and E)

Question 5

Which type of muscle tissue has cells that branch?

Accepted Answer

A)   skeletal muscle
B)   smooth muscle
C)   cardiac muscle
D)   both skeletal and cardiac muscle
E)   both cardiac and smooth muscleF) A) and E)
G) C) and D)

Question 6

Which of the following actions is caused by contraction of skeletal muscle?

Accepted Answer

A)   contraction of the heart
B)   moving your feet in walking
C)   movement of food through the digestive tract
D)   emptying of the urinary bladder
E)   vasoconstrictionF) A) and C)
G) A) and B)

Question 7

-What does "C" represent on the diagram?

Accepted Answer

A)   threshold
B)   depolarization
C)   depolarization phase of action potential
D)   repolarization phase of action potentialE) A) and C)
F) A) and B)

Question 8

The region of the sarcomere that contains both actin and myosin myofilaments is called the

Accepted Answer

A)   I band.
B)   A band.
C)   Z disk.
D)   H zone.
E)   M line.F) B) and E)
G) A) and E)

Question 9

Which of the following events occurs during the lag phase of a muscle twitch?

Accepted Answer

A)   Muscle fibers shorten.
B)   Cross-bridges form, move, release, and reform many times.
C)   The action potential is propagated from presynaptic to postsynaptic membrane.
D)   Calcium is pumped back into the sarcoplasmic reticulum.
E)   All of these events occur in the lag phase.F) B) and E)
G) A) and B)

Question 10

Acetylcholine is released from the presynaptic terminal by the process of

Accepted Answer

A)   exocytosis.
B)   diffusion.
C)   phagocytosis.
D)   active transport.
E)   endocytosis.F) A) and D)
G) C) and E)

Question 11

Movements of the body are usually smooth and occur at differing rates because

Accepted Answer

A)   they are a mixture of isotonic and isometric contractions.
B)   motor units contract out of phase at their own particular rates.
C)   most muscle contractions closely resemble individual muscle twitches.
D)   muscles of different sizes contract at different rates.
E)   of the all or none principle.F) A) and B)
G) A) and E)

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 E)
G) A) and C)

Question 13

In smooth muscle, most of the calcium needed for muscle contraction

Accepted Answer

A)   is in the dense bodies.
B)   enters from extracellular fluid.
C)   is attached to the intermediate filaments.
D)   must be activated by myosin kinase.
E)   is stored in the sarcoplasmic reticulum.F) A) and C)
G) D) and E)

Question 14

The active sites to which cross-bridges attach are found on the

Accepted Answer

A)   sarcoplasmic reticulum.
B)   actin myofilaments.
C)   Z disks.
D)   T tubules.
E)   myosin myofilaments.F) C) and D)
G) D) and E)

Question 15

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) A) and C)

Question 16

Rigor mortis occurs after death because

Accepted Answer

A)   cross-bridges form but can't release.
B)   calcium is actively transported back to the sarcoplasmic reticulum.
C)   anaerobic respiration is occurring.
D)   myosin levels decline at death.
E)   cross-bridges never form.F) A) and B)
G) B) and C)

Question 17

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

Accepted Answer

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

Question 18

Which of the following is true about skeletal muscle?

Accepted Answer

A)   Sensory neurons stimulate muscles to contract.
B)   There are very few blood vessels in skeletal muscle.
C)   Every muscle fiber receives a branch of an axon from the nerve.
D)   There are very few nerve fibers in a muscle.
E)   All of these are true.F) A) and E)
G) C) and D)

Question 19

-What does "C" represent on the diagram?

Accepted Answer

A)   myosin myofilament
B)   actin myofilament
C)   sarcomere
D)   Z disk
E)   cross-bridgeF) A) and E)
G) C) and E)

Question 20

An isometric contraction is described as

Accepted Answer

A)   action potential frequency is high enough that no relaxation of muscle fibers occurs.
B)   a muscle produces constant tension during contraction.
C)   a muscle produces an increasing tension as the length remains constant.
D)   a muscle produces increasing tension as it shortens.
E)   a muscle produces tension, but the length of the muscle is increasing.F) A) and E)
G) All of the above

Exam 9: Muscular System: Histology and Physiology

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

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-What does "C" represent on the diagram?

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The region of the sarcomere that contains both actin and myosin myofilaments is called the

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What are caveolae?

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Which type of muscle tissue has cells that branch?

Correct AnswerverifiedShow Answer

Movements of the body are usually smooth and occur at differing rates because

Correct AnswerverifiedShow Answer

The active sites to which cross-bridges attach are found on the

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Which of the following is part of a thin myofilament?

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Actin myofilaments

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Acetylcholine is released from the presynaptic terminal by the process of

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Which of the following actions is caused by contraction of skeletal muscle?

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In smooth muscle, most of the calcium needed for muscle contraction

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Which of the following is NOT true of the latch state of smooth muscle contraction?

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-The figure illustrates a detailed drawing of the neuromuscular junction. What does "D" represent?

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-What does "C" represent on the diagram?

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An isometric contraction is described as

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Which of the following is true about skeletal muscle?

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-What does "A" represent on the diagram?

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Rigor mortis occurs after death because

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Which of the following events occurs during the lag phase of a muscle twitch?

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