Question 1

What is a triad?

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 2

Smooth muscle is regulated by all of the following except

Accepted Answer

A)   the autonomic nervous system.
B)   neurotransmitters.
C)   the somatic nervous system.
D)   hormones.
E)   prostaglandins.F) B) and D)
G) All of the above

Question 3

During a muscle fiber contraction, which of the following decreases in size? Check all that apply.

Accepted Answer

A)   A band
B)   Entire sarcomere
C)   H zone
D)   I bandE) A) and D)
F) A) and C)

Question 4

In smooth muscle, most of the Ca2+ 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 D)
G) C) and D)

Question 5

The length of the resting sarcomere is

Accepted Answer

A)   longer than the length of a contracted sarcomere.
B)   shorter than the length of a contracted sarcomere.
C)   the same length as a contracted sarcomere.
D)   the same length as the muscle fiber.
E)   the same length as the myofibril.F) C) and E)
G) B) and C)

Question 6

In smooth muscle, cross-bridging occurs due to

Accepted Answer

A)   Ca2+ binding to troponin.
B)   Ca2+ binding to calmodulin.
C)   myosin kinase adding a phosphate to myosin heads.
D)   both Ca2+ binding to troponin and calmodulin.
E)   both Ca2+ binding to calmodulin and myosin kinase adding a phosphate to myosin heads.F) A) and D)
G) B) and E)

Question 7

Which of the following is NOT an age-related change in skeletal muscle?

Accepted Answer

A)   Loss of muscle strength
B)   Loss of synapse surface area
C)   Loss of fast-twitch fibers
D)   Decreased recovery time
E)   Decrease in motor unitsF) A) and D)
G) C) and E)

Question 8

A child ingested an organophosphate poison used to kill insects. Soon the child's muscles began spastic contractions. Predict what occurred at the synaptic cleft.

Accepted Answer

A)   Decreased release of acetylcholine from presynaptic neurons
B)   Increased accumulation of acetylcholine in the synapse
C)   Binding of the poison to acetylcholine receptors leading to inhibition of stimulation
D)   Increased breakdown of acetylcholine in the synaptic cleft
E)   Both increased accumulation of acetylcholine in the synapse and increased breakdown of acetylcholine in the synaptic cleft are correct.F) D) and E)
G) A) and E)

Question 9

The stretch of elastic components of a muscle adds to the increased tension during

Accepted Answer

A)   incomplete tetanus.
B)   twitch.
C)   multiple wave summation.
D)   all-or-none response.
E)   None of the choices are correct.F) A) and B)
G) None of the above

Question 10

Why is the contraction strength of smooth muscle relatively independent of its resting length?

Accepted Answer

A)   It gets nearly all of its Ca2+ from the extracellular fluid.
B)   It does not have intercalated discs.
C)   It does not have sarcomeres.
D)   It is regulated by a length-tension relationship.
E)   It is involuntary muscle.F) A) and E)
G) B) and E)

Question 11

What is the role of myosin phosphatase?

Accepted Answer

A)   To aid in rapidly developing action potentials
B)   To form shallow invaginations of the plasma membrane
C)   To maintain relatively constant tension for a period of time
D)   To function as the intracellular cytoskeleton
E)   To serve as an enzyme that removes phosphate from myosinF) B) and D)
G) A) and E)

Question 12

Incomplete tetanus

Accepted Answer

A)   is the time during which the tissue cannot respond again.
B)   results in complete and incomplete tetanus.
C)   is the condition in which the muscle fiber only partially relaxes between contractions.
D)   is the condition in which stimuli occur so rapidly that there are no intervening relaxations.
E)   is the constant tension produced by muscles for long periods of time.F) B) and E)
G) A) and B)

Question 13

Sarcoplasm is the

Accepted Answer

A)   plasma membrane of a muscle fiber.
B)   cytoplasm of a muscle fiber.
C)   structural and functional unit of the skeletal muscle fiber.
D)   contractile thread that extends the length of the muscle fiber.
E)   protein strand composed of actin or myosin.F) A) and E)
G) None of the above

Question 14

Betsy took a fall and broke her arm, which required that she wear a cast for a prolonged period of time. When she took the cast off, she was alarmed to see that her muscles

Accepted Answer

A)   looked the same as they did before the fall.
B)   had undergone atrophy.
C)   had undergone hypertrophy.
D)   seemed to have an increase in blood flow.E) A) and B)
F) B) and C)

Question 15

Intense exercise that results in a great deal of anaerobic activity

Accepted Answer

A)   converts some slow-twitch fibers into fast-twitch fibers.
B)   increases muscular strength and mass.
C)   enlarges slow-twitch fibers.
D)   decreases the efficiency of fast-twitch fibers.
E)   decreases muscle strength and mass.F) A) and C)
G) B) and E)

Question 16

Which type of muscle tissue has neuromuscular junctions?

Accepted Answer

A)   Skeletal muscle
B)   Smooth muscle
C)   Cardiac muscleD) A) and B)
E) All of the above

Question 17

What is an oxygen deficit?

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) D) and E)
G) A) and C)

Question 18

A sarcomere extends from

Accepted Answer

A)   one Z disk to an adjacent Z disk.
B)   one T tubule to the next T tubule.
C)   the middle of the I band to the middle of the A band.
D)   the H zone to the I band.
E)   the M line to the next M line.F) A) and C)
G) A) and B)

Question 19

Consider the following four phrases and select the one that does not belong with the others.

Accepted Answer

A)   Anaerobic metabolism
B)   Lactate production
C)   Fast twitch fibers
D)   Fuels runner in a marathon
E)   Muscle fibers split ATP rapidlyF) A) and E)
G) None of the above

Question 20

If all of the Ca2+ within a muscle fiber was removed, which of the following could still occur?

Accepted Answer

A)   The heads of the myosin myofilaments would bind to G-actin to form cross-bridges.
B)   An action potential that was produced at the neuromuscular junction would be propagated along the sarcolemma.
C)   The troponin molecules bound to G actin molecules would be released, causing tropomyosin to move.
D)   The heads of the myosin molecules would return to their resting position, and the recovery stroke would occur.E) B) and C)
F) C) and D)

Exam 9: Muscular System: Histology and Physiology

In smooth muscle, cross-bridging occurs due to

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The length of the resting sarcomere is

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During a muscle fiber contraction, which of the following decreases in size? Check all that apply.

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Consider the following four phrases and select the one that does not belong with the others.

Correct AnswerverifiedShow Answer

A child ingested an organophosphate poison used to kill insects. Soon the child's muscles began spastic contractions. Predict what occurred at the synaptic cleft.

Correct AnswerverifiedShow Answer

Which of the following is NOT an age-related change in skeletal muscle?

Correct AnswerverifiedShow Answer

Intense exercise that results in a great deal of anaerobic activity

Correct AnswerverifiedShow Answer

The stretch of elastic components of a muscle adds to the increased tension during

Correct AnswerverifiedShow Answer

Which type of muscle tissue has neuromuscular junctions?

Correct AnswerverifiedShow Answer

What is a triad?

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A sarcomere extends from

Correct AnswerverifiedShow Answer

In smooth muscle, most of the Ca2+ needed for muscle contraction

Correct AnswerverifiedShow Answer

What is an oxygen deficit?

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Why is the contraction strength of smooth muscle relatively independent of its resting length?

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What is the role of myosin phosphatase?

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If all of the Ca2+ within a muscle fiber was removed, which of the following could still occur?

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Incomplete tetanus

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Betsy took a fall and broke her arm, which required that she wear a cast for a prolonged period of time. When she took the cast off, she was alarmed to see that her muscles

Correct AnswerverifiedShow Answer

Smooth muscle is regulated by all of the following except

Correct AnswerverifiedShow Answer

Sarcoplasm is the

Correct AnswerverifiedShow Answer

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In smooth muscle, most of the Ca²⁺ needed for muscle contraction

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If all of the Ca²⁺ within a muscle fiber was removed, which of the following could still occur?

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