Identify the incorrect statement about a single motor unit.
A) The more neurons involved, the more powerful the contraction.
B) The smaller the number of muscle fibers, the more precise the movement.
C) Fine motor skills depend on the development of small motor units.
D) Some motor units include as many as 2000 muscle fibers.
E) Muscle fibers of one motor unit intermingle with the fibers of another motor unit.
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Question 2) In an isotonic contraction,
A) muscle tension exceeds the load and the muscle lifts the load.
B) tension rises and falls but the muscle length is constant.
C) the peak tension is less than the load.
D) many twitches always fuse into one.
E) postural muscles stabilize the vertebrae.
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Question 3) In which of the following would the motor units have the fewest muscle fibers?
A) muscles of the neck
B) postural muscles of the back
C) muscles that control the eyes
D) thigh muscles
E) calf muscles
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Question 4) You try to pick up an object and discover that it is much heavier than you expected. Which process must occur in the muscle to increase tension so you can pick up the object?
A) wave summation
B) isotonic contraction
C) complete tetanus
D) recruitment
E) treppe
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Question 5) A weight-lifter strains to lift a heavy weight and there is no movement of the person's arms holding on to the weight. This type of contraction is called a(n) ________ contraction.
A) isometric
B) tetanus
C) isotonic
D) treppe
E) concentric
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Question 6) The type of contraction in which the muscle fibers do not shorten is called
A) tetany.
B) treppe.
C) concentric.
D) isotonic.
E) isometric.
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Question 7) The increase in muscle tension that is produced by increasing the number of active motor units is called
A) incomplete tetanus.
B) complete tetanus.
C) treppe.
D) wave summation.
E) recruitment.
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Question 8) A single motor neuron together with all the muscle fibers it innervates is called a(n)
A) end foot.
B) end plate.
C) motor unit.
D) dermatome.
E) myotome.
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Question 9) Detachment of myosin cross-bridges occurs during the
A) contraction phase.
B) relaxation phase.
C) stimulus phase.
D) latent period.
E) isotonic period.
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Question 10) The point in a muscle twitch when the troponin is bound to calcium is called the
A) contraction phase.
B) relaxation phase.
C) stimulus phase.
D) latent period.
E) isotonic period.
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