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Physiology > Section 5, Exam 2 > Flashcards

Section 5, Exam 2 Flashcards

1
Q

A specialized proprioceptor that sends information to the CNS about muscle length and the velocity of stretch (mm/s)

A

Muscle spindle

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2
Q

Muscle spindles are oriented in ______ to extrafusal muscle fibers throughout the fleshy part of skeletal muscle

A

Parallel

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3
Q

What type (motor or sensory) of innervation does the muscle spindle receive?

A

Both motor and sensory (group Ia and group II)

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4
Q

What is the only receptor that receives both sensory and motor innervation?

A

The muscle spindle

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5
Q

What are muscle spindles enclosed in?

A

A fusiform shaped connective tissue capsule

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6
Q

Skeletal muscle fibers outside the capsule are termed ________.

A

Extrafusal muscle fibers

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7
Q

Term used to refer to structures inside the fusiform shaped connective tissue capsule

A

intrafusal

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8
Q

On average, about how many nuclear bag fibers do muscle spindles have? Nuclear chain fibers?

A

2; 4-6

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9
Q

When A gamma efferent axons stimulate muscle fibers, what will happen to the middle of the muscle spindle?

A

It will stretch due to contraction in the polar region in the m. spindle

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10
Q

The property that makes material resistant to a change in form, shape, or structure

A

Viscosity

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11
Q

The equatorial region of both the nuclear bag and chain fibers are ______ viscous comparison to the polar regions

A

Less viscous

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12
Q

The polar regions of both the nuclear bag and chain fibers are _____ sensitive to stretch or length change

A

Less

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13
Q

What region of the muscle spindle contains more contractile proteins?

A

Polar regions

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14
Q

Polar regions are more resistant to change its form or structure because of ___________ between protein molecules.

A

Electrostatic attraction

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15
Q

The equatorial regions of both the nuclear bag and chain intrafusal muscle fibers are innervated by?

A

Ia (A alpha) afferent axons

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16
Q

What does the “a” indicate in the Ia axon classification?

A

Innervation of the annulospiral nerve

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17
Q

What are annulospiral nerve endings also known as?

A

The primary endings

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18
Q

In most cases, what type of intrafusal muscle fiber does Group II afferent axons innervate?

A

Nuclear chain fibers (sometimes nuclear bag, but significantly less instances)

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19
Q

Where in the muscle spindle do Group II axons innervate?

A

Polar region

20
Q

True or False:

Group II has a slower AP conduction velocity than the Ia axons.

A

True; they also have smaller sensory axons

21
Q

What are group II nerve endings also known as?

A

The secondary endings or the flower spray endings

22
Q

Where do A gamma motor neurons connect?

A

ONLY the polar regions of the nuclear bag and nuclear chain fibers

23
Q

What does the contracting of the polar myofibrils in the muscle spindle cause?

A

A stretch of the spindle’s equatorial region (due to both ends of intrafusal muscle fibers being pulled)

24
Q

What does activation of the gamma motor neurons prevent while extrafusal muscle contracts?

A

Prevents the muscle spindle from becoming slack

25
Q

Why does the muscle spindle need to remain taught even during muscle contraction?

A

To maintain sensitivity so the sensory receptors can send information to the CNS

26
Q

True or false:

Activation of A gamma axons causes activation of muscle contraction.

A

False; A gamma only sensitizes the equatorial region of the muscle spindle. There is not enough of a pull (or stretch) on the equatorial region to cause a muscle contraction

27
Q

The discharge of nerve action potentials at any constant or fixed muscle length

A

The static response

28
Q

With the static response, a greater length give you ________.

A

A greater frequency of action potentials

29
Q

What afferent neuron(s) have a static response?

A

Group Ia and Group II (primarily)

30
Q

The discharge of APs during the stretch or muscle length change.

A

The dynamic response

31
Q

What afferent neuron(s) are velocity sensitive?

A

Group Ia

32
Q

Static response signals of fixed length to the CNS:

Longer muscle length —> ______
Shorter muscle length —> ______

A

Greater AP (impulse) frequency; Lower AP (impulse) frequency

33
Q

Dynamic Response signals of velocity of length change to CNS:

Greater stretch velocity –> _____
Slower stretch velocity –> _____

A

Greater AP (impulse) frequency; Lower AP (impulse) frequency

34
Q

Physical properties innervated by _____ are low viscosity stretch sensitive equatorial region

A

Ia

35
Q

Physical properties innervated by _____ are high viscosity stretch resistant polar region

A

II

36
Q

Conduction properties of the axons of ____ are larger in diameter causing greater impulse conduction velocity with faster response.

A

Ia

37
Q

Conduction properties of the axons of ____ are smaller in diameter causing lower conduction velocity with slower response.

A

II

38
Q

A specialized proprioceptor that sends information to the CNS about muscle contraction (or shortening force) and muscle stretch (or lengthening force)

A

GTO

39
Q

GTO’s are oriented in ____ to 15-20 extrafusal muscle fibers in the musculotendinous junction of skeletal muscle

A

Series

40
Q

The GTO is composed of a network of _______________ arranged in series with 15-20 extrafusal muscle fibers.

A

Small unmyelinated nerve fibers

41
Q

True or False:

The nerve fibers of the GTO are enclosed in a capsule.

A

True

42
Q

The nerve fibers are branches of _______.

A

A single Ib myelinated primary afferent axon

43
Q

True or False:

The GTO has no motor nerve connection or innervation.

A

True

44
Q

What stimulates the GTO?

A

Muscle tension developed during a muscle contraction

45
Q

GTOs send a ____ frequency of APs to the CNS during muscle contraction and a ______ frequency of APs during muscle stretch.

A

Greater; lower

46
Q

Do muscle spindles send action potentials during muscle contraction?

A

No, because they are slack

Physiology (15 decks)

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