Question 1

Which of the following is true?

Accepted Answer

A)   Muscle fatigue has no influence on the force of contractions.
B)   A threshold stimulus will cause contraction of a muscle fiber.
C)   A subthreshold stimulus causes a muscle contraction.
D)   Motor units do not obey the "all or none" law.
E)   A threshold stimulus will not affect motor units.F) B) and D)
G) A) and E)

Question 2

The sites where a chemical substance is transmitted from the presynaptic terminal of an axon to the postsynaptic membrane of a muscle fiber are called

Accepted Answer

A)   neuromuscular junctions.
B)   sarcomeres.
C)   myofilaments.
D)   Z disks.
E)   cell body of neuron.F) All of the above
G) A) and C)

Question 3

Which of the following is true?

Accepted Answer

A)   The greater the overlap of actin and myosin, the stronger the contraction.
B)   Overstretching a muscle will increase its tension.
C)   Optimal actin and myosin overlap will produce maximal contraction.
D)   The greatest amount of tension is achieved when actin and myosin do not overlap.
E)   Tension is great when actin and myosin overlap as much as they can.F) B) and D)
G) C) and D)

Question 4

The sarcoplasmic reticulum

Accepted Answer

A)   stores calcium ions.
B)   shortens during muscle contraction.
C)   transmits nerve impulses to the myofibrils.
D)   connects adjacent sarcomeres.
E)   covers the muscle fiber.F) C) and D)
G) All of the above

Question 5

Which type of muscle tissue causes contraction of the heart?

Accepted Answer

A)   skeletal muscle
B)   smooth muscle
C)   cardiac muscleD) B) and C)
E) None of the above

Question 6

Lack of acetylcholinesterase in the synaptic cleft would result in

Accepted Answer

A)   a decrease in acetylcholine production by the motor neuron.
B)   continuous stimulation of the postsynaptic membrane.
C)   rapid degradation of acetylcholine.
D)   relaxation of the muscle.
E)   continuous stimulation of the presynaptic membrane.F) All of the above
G) A) and B)

Question 7

Functionally, smooth muscle

Accepted Answer

A)   is well adapted to anaerobic metabolism.
B)   exhibits autorhythmic contractions.
C)   contracts in response to slow increases in length.
D)   is unable to maintain tone.
E)   rapidly develops an oxygen debt.F) C) and D)
G) A) and E)

Question 8

Muscles exhibit the property of excitability. This means that the muscle

Accepted Answer

A)   shortens its length.
B)   recoils to its original resting length.
C)   stretches beyond its normal length.
D)   responds to stimulation by the nervous system.
E)   excites itself.F) C) and D)
G) B) and C)

Question 9

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 D)
G) A) and C)

Question 10

What is a cross-bridge?

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 oxygen taken in that exceeds the oxygen required for resting metabolismF) A) and E)
G) All of the above

Question 11

-The figure illustrates the neuromuscular junction. What does "B" represent?

Accepted Answer

A)   presynaptic terminal
B)   muscle fiber
C)   neuromuscular junction
D)   axon branch
E)   myofibrilsF) D) and E)
G) None of the above

Question 12

The time between application of the stimulus to a motor neuron and the beginning of contraction is called the _____ phase.

Accepted Answer

A)   contraction
B)   relaxation
C)   latent or lag
D)   refractory
E)   thresholdF) A) and B)
G) None of the above

Question 13

A drug that interferes with the active transport of calcium ions from the sarcoplasm back into the sarcoplasmic reticulum would result in

Accepted Answer

A)   relaxation of the muscle fiber.
B)   contraction with no relaxation.
C)   muscle hypertrophy.
D)   fibrosis of the muscle.
E)   an imbalance of blood calcium.F) A) and B)
G) C) and D)

Question 14

-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) None of the above
F) C) and D)

Question 15

Which type of muscle tissue would cause flexion and extension of the arm?

Accepted Answer

A)   skeletal muscle
B)   smooth muscle
C)   cardiac muscleD) B) and C)
E) All of the above

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) B) and D)
G) B) and C)

Question 17

A condition in which stimuli occur so rapidly that there are no intervening relaxations between contractions is called

Accepted Answer

A)   complete tetanus.
B)   incomplete tetanus.
C)   involuntary paralysis.
D)   all or none tetanus.
E)   treppe.F) B) and D)
G) None of the above

Question 18

-What does "D" represent on the diagram?

Accepted Answer

A)   myosin myofilament
B)   actin myofilament
C)   sarcomere
D)   Z disk
E)   cross-bridgeF) A) and E)
G) None of the above

Question 19

What are dense bodies and intermediate filaments in smooth muscle?

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) B) and C)
G) B) and E)

Question 20

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) C) and E)
G) B) and C)

Exam 9: Muscular System: Histology and Physiology

Which of the following is true about skeletal muscle?

Correct AnswerverifiedShow Answer

A drug that interferes with the active transport of calcium ions from the sarcoplasm back into the sarcoplasmic reticulum would result in

Correct AnswerverifiedShow Answer

Muscles exhibit the property of excitability. This means that the muscle

Correct AnswerverifiedShow Answer

-The figure illustrates the neuromuscular junction. What does "B" represent?

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Functionally, smooth muscle

Correct AnswerverifiedShow Answer

-What does "C" represent on the diagram?

Correct AnswerverifiedShow Answer

The time between application of the stimulus to a motor neuron and the beginning of contraction is called the _____ phase.

Correct AnswerverifiedShow Answer

Which of the following is true?

Correct AnswerverifiedShow Answer

The sarcoplasmic reticulum

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Lack of acetylcholinesterase in the synaptic cleft would result in

Correct AnswerverifiedShow Answer

-What does "D" represent on the diagram?

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Which of the following is true?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Which type of muscle tissue would cause flexion and extension of the arm?

Correct AnswerverifiedShow Answer

Rigor mortis occurs after death because

Correct AnswerverifiedShow Answer

The sites where a chemical substance is transmitted from the presynaptic terminal of an axon to the postsynaptic membrane of a muscle fiber are called

Correct AnswerverifiedShow Answer

A condition in which stimuli occur so rapidly that there are no intervening relaxations between contractions is called

Correct AnswerverifiedShow Answer

Which type of muscle tissue causes contraction of the heart?

Correct AnswerverifiedShow Answer

What is a cross-bridge?

Correct AnswerverifiedShow Answer

What are dense bodies and intermediate filaments in smooth muscle?

Correct AnswerverifiedShow Answer

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