QUIZ 8 Flashcards

1
Q

a motor neuron pool consists of:

-all of the motor neurons that project to a given muscle
-all of the motor neurons that project to a given limb
-all of the motor neurons within a single segment of spinal cord
-a single motor neuron and all of its afferent interneurons
-a single motor neuron and all of the muscles it innervates

A

all of the motor neurons that project to a given muscle

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2
Q

a specialized motor unit, with an average size of three muscle fibers, controls:

-finger movements
-the large, fast contracting muscles used in sprinting
-postural muscle
-eye muscles

A

eye muscles

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3
Q

which of the following statements about the organization of muscles and motor neurons is false?

-successive stimulation of muscles can produce force levels that build up over time
-the fastest, strongest muscle fibers can produce the most sustained force output
-large motor neurons are recruited only at higher levels of stimulus intensity
-red muscle fibers contract slowly and produce the smallest amount of force

A

the fastest, strongest muscle fibers can produce the most sustained force output

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4
Q

the condition called “fused tetanus” refers to:

-a sustained maximal contraction due to high frequency input to motor unit firing
-lockjaw symptoms resulting from exposure to the tetanus toxin
-the response of single muscle fibers to a single action potential input
-an excessive contraction that results in the fusing together of muscle fibers

A

a sustained maximal contraction due to high frequency input to motor unit firing

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5
Q

group 1a afferents are coiled around ____ fibers

-all extrafusal muscle fibers
-only S-type extrafusal muscle fibers
-both nuclear bag and nuclear chain fibers

A

both nuclear bag and nuclear chain fibers

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6
Q

if the muscle is actively contracted and shortens during voluntary movement, which of the following would you expect to increase their discharge rate?
(select multiple)

-golgi tendon organs
-gamma motor neurons
-muscle spindles
-alpha motor neurons

A

-golgi tendon organs
-gamma motor neurons
-alpha motor neurons

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7
Q

in a stretch reflex with a high gain, a ____ stretch of a muscle would lead to ____ increase in extrafusal muscle tension

-small; a large
-small; no
-large; a small
-large; no

A

small; a large

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8
Q

gamma (γ) motor neuron firing rates are typically high
(select multiple)

-during difficult and precise movements (walking on a narrow beam)
-during voluntary stretching
-during unpredictable conditions (standing on a moving bus)

A

-during difficult and precise movements (walking on a narrow beam)
-during unpredictable conditions (standing on a moving bus)

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9
Q

the flexion-crossed extension reflex would occur in response to which activity?

-holding a box steady as more items are added to it
-coordinating your legs to squat
-stimulation of the mesencephalic locomotor region
-stepping on a sharp object
-a knee tap with a reflex hammer

A

stepping on a sharp object

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10
Q

the local circuits in the spinal cord that are fully capable of controlling the timing and coordination of complex locomotion are called ____

A

central pattern generators

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