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) B) and D)
G) None of the above

Question 2

An isotonic 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 during contraction.
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 C)
G) B) and E)

Question 3

Oxygen deficit represents

Accepted Answer

A)  the amount anaerobic metabolism must increase after exercise.
B)  the amount of oxygen converted to lactic acid during exercise.
C)  the amount of carbon dioxide that cells need to eliminate.
D)  conversion of pyruvic acid to lactic acid.
E)  the amount of oxygen that cells need to replenish ATP supplies after exercise.F) A) and E)
G) B) and E)

Question 4

Hypertrophy of skeletal muscles from weight lifting is caused by an increase in the

Accepted Answer

A)  number of muscle fibers.
B)  size of muscle fibers.
C)  number of striations.
D)  number of nuclei within the muscle fibers.
E)  number of muscle cells.F) D) and E)
G) A) and D)

Question 5

Which type of muscle tissue has spindle-shaped cells?

Accepted Answer

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

Question 6

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) C) and D)
G) All of the above

Question 7

Too much acetylcholinesterase causes

Accepted Answer

A)  continuous stimulation of the muscle fiber.
B)  rapid degradation of acetycholine.
C)  voltage-gated calcium ion channels opening in the presynaptic terminal.
D)  an increase in sodium uptake by the muscle fiber.
E)  exocytosis of synaptic vesicles.F) B) and D)
G) A) and B)

Question 8

Whole muscles can respond in a graded fashion to stimuli by varying

Accepted Answer

A)  the force of contraction of individual muscle fibers.
B)  the number of motor units recruited.
C)  the amplitude of the action potential.
D)  the frequency of stimulus.
E)  thresholds.F) B) and C)
G) A) and C)

Question 9

Myosin is also known as the

Accepted Answer

A)  thick myofilament.
B)  thin myofilament.
C)  intermediate myofilament.
D)  short myofilament.
E)  sarcomere.F) A) and E)
G) B) and E)

Question 10

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) None of the above
G) A) and E)

Question 11

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

Accepted Answer

A)  synaptic vesicles
B)  synaptic cleft
C)  sarcolemma
D)  presynaptic terminal
E)  postsynaptic membraneF) None of the above
G) B) and E)

Question 12

In order for muscle relaxation to occur,

Accepted Answer

A)  calcium ions must be transported to troponin.
B)  power strokes slow down.
C)  the active sites on actin must be blocked.
D)  sodium ions must be actively transported to troponin.
E)  the active sites on myosin must be uncovered.F) All of the above
G) A) and E)

Question 13

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

Question 14

A concentric 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 during contraction.
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 B)
G) B) and E)

Question 15

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

Question 16

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 calcium channels.F) A) and B)
G) B) and E)

Question 17

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

Question 18

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 B)
G) None of the above

Question 19

Tetanus of a muscle is thought to be caused by

Accepted Answer

A)  high calcium ion concentrations in the sarcoplasm.
B)  the rapid movement of sodium ions back into the sarcoplasmic reticulum.
C)  an increase in stimulus strength.
D)  increased temperature in the active muscle.
E)  decreased amounts of calcium ions in muscle tissue.F) B) and E)
G) B) and D)

Question 20

Which of the following would contribute to muscular fatigue in the muscle fiber?

Accepted Answer

A)  the emotional state of an individual
B)  depletion of ATP reserves
C)  inability of the motor neuron to produce sufficient quantities of acetylcholine
D)  depletion of neurotransmitter
E)  blocked receptors in the postsynaptic membraneF) D) and E)
G) B) and E)

Exam 9: Muscular System: Histology and Physiology

An isotonic contraction is described as

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Hypertrophy of skeletal muscles from weight lifting is caused by an increase in the

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Myosin is also known as the

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Oxygen deficit represents

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

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Whole muscles can respond in a graded fashion to stimuli by varying

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A concentric contraction is described as

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Which type of muscle tissue has spindle-shaped cells?

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

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Which of the following would contribute to muscular fatigue in the muscle fiber?

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

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In order for muscle relaxation to occur,

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Which of the following is true?

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Intense exercise that results in a great deal of anaerobic activity

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Too much acetylcholinesterase causes

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Tetanus of a muscle is thought to be caused by

Correct AnswerverifiedShow Answer

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

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

Myosin phosphatase

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