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Physiology > Physiology Quiz 4 (Reflex Physiology) > Flashcards

Physiology Quiz 4 (Reflex Physiology) Flashcards

0
Q

Purpose of flexor withdrawal reflex

A

Protect tissue from damage

Minimize damage when you come into contact with damaging stimuli

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1
Q

Reflex activity

A

Predictable, stereo typical response to a specific stimulus

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2
Q

Where does the sensory afferent neuron travel to in the flexor withdrawal pathway?

A

Travels to the spinal cord through the dorsal root ganglia to branch off one way sending sensory info up to the brain, and another way, to synapse upon several interneurons

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3
Q

What is the pathway the signal follows from the afferent neuron to the alpha motor neuron activating the hamstrings of the affected leg? (Flexor withdrawal reflex)

A

Sensory afferent–> excitatory interneuron–> excitatory interneuron–> alpha motor neuron inner acting hamstrings (contracts hamstrings)

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4
Q

Pathway the signal follows from the sensory afferent neuron to the quads of the affected leg

A

Sensory afferent–> excitatory interneuron–> inhibitory interneuron–> alpha motor neuron innervating quads (quad does not contract)

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5
Q

Pathway of signal that goes from sensory afferent neuron to quads of unaffected leg (flexor withdrawal reflex)

A

Sensory afferent–> excitatory interneuron–> excitatory interneuron–> axon crosses to other side of spinal cord–> excitatory interneuron–> alpha motor neuron innervating quads (quads contract)

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6
Q

Pathway of signal that goes from sensory afferent neuron to hamstrings of unaffected leg (flexor withdrawal reflex)

A

Sensory afferent–> excitatory interneuron–> excitatory interneuron–>crosses to other side of spinal cord–> inhibitory interneuron–> alpha motor neuron innervating hamstrings (hamstrings do not contract)

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7
Q

Reciprocal inhibition

A

When one muscle is contracted (hamstrings) the opposite muscle is inhibited (quads). This happens in the flexor withdrawal reflex so that the affected leg is able to bend at the knee and move away from harm.
This process is typical of reflex and voluntary motor activity

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8
Q

Crossed extensor component (of flexor withdrawal reflex)

A

Opposite leg extending as the affected leg is flexing

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9
Q

What is the value of the flexor withdrawal reflex?

A

Protect tissue from damage

Support body weight when one leg is flexing due to nociceptive input

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10
Q

What conditions will interfere with the flexor withdrawal reflex?

A

Neuropathy (happens in diabetes)

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11
Q

Myotatic reflex

A

Skeletal muscle responds to stretch by contracting (muscle spindles)

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12
Q

Other names for myotatic reflex

A

Spindle reflex
Stretch reflex
Deep tendon reflex

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13
Q

Spinal level reflex

A

A reflex that occurs at the spinal cord level

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14
Q

Is myotatic reflex a spinal level reflex?

A

Yes

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15
Q

Purpose of myotatic reflex

A

Keep body upright during postural perturbations (ie, using elevator, uneven terrain)

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16
Q

Where are muscle spindles?

A

Randomly disbursed in muscles

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17
Q

What is the only monosynaptic reflex in the body?

A

Myotatic reflex

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18
Q

Are there interneurons in the myotatic reflex?

A

No

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19
Q

Where does the 1a afferent nerve go from the muscle spindle?

A

To spinal cord via dorsal root ganglion

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20
Q

What type of afferent nerve carries info from the muscle spindle to the CNS?

A

1a

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21
Q

Proprioception

A

Ability to know where body parts are without looking at them

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22
Q

What tends to happen to gait in people with diabetes/neuropathy and why?

A

Either:

  1. Steppage gait
  2. Watch feet

Happens because proprioception is compromised

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23
Q

Steppage gait

A

Walking with exaggeration of picking up feet

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24
Q

How does muscle spindle carry proprioceptive info to brain?

A

1a afferent nerve branches off after the dorsal root ganglion and goes up to the brain

25
Q

Nerve pathway from muscle spindle to hamstring

A

1a afferent from spindle–> enters dorsal root ganglion–> inhibitory interneuron–> alpha motor efferent neuron innervating hamstring (inhibits hamstring via reciprocal inhibition)

26
Q

Gamma motor neuron

A

Smaller than 1a efferents, myelinated

27
Q

Intrafusal fiber

A

Referring to muscle spindle itself

28
Q

Extrafusal fibers

A

Standard muscle cells surrounding spindle

29
Q

Function of muscle spindle

A

Reflex

CNS input about muscle length

30
Q

Where are contractile filaments located on spindle

A

At tips of spindle (innervating by gamma motor neurons)

None in middle of spindle

31
Q

What increases the firing rate of the 1a afferent is coming from the spindle?

A

center of the spindle is stretching

32
Q

Alpha-gamma coactivation

A

Activating both alpha and gamma motor neurons during contraction (happens when you do a contraction)

33
Q

Cerebellum role in muscle contraction/coordination

A

Makes adjustments in muscle activation based on info from spindles (info about muscle length)
-tested by having a patient hold their arms in front of body with elbows bent, therapist pulls forearms away and patient is instructed to resist, therapist let’s go…if patient hits self in chest, indicates problem with cerebellum

34
Q

Subunits of spindles

A

Nuclear bag fibers

Nuclear chain fibers

35
Q

How many subunits of spindle fibers are there?

A

12-15

36
Q

Nuclear bag fibers AKA

A

Dynamic fibers

37
Q

Nuclear chain fibers AKA

A

Static component

38
Q

What are nuclear bag fibers most effective at measuring?

A

Muscle length as the muscle length changes

39
Q

What is nuclear chain fiber most effective at monitoring?

A

Muscle length when it is unchanging

40
Q

Can nuclear bag fibers and nuclear chain fibers perform each other’s function?

A

Yup, they are just not as good at it

41
Q

(Nuclear bag/nuclear chain) fibers have lower viscosity

A

Bag

42
Q

Nuclear (bag/chain) fibers have higher viscosity

A

Chain

43
Q

Role of gamma motor fibers in spindles

A

Contract the filaments at the tips of the spindles in synchrony with the extrafusals

44
Q

What is activated by higher motor control centers during voluntary and reflex motor activity?

A

Alpha and gamma motor neuron

45
Q

What allows the higher motor control centers to monitor muscle length during voluntary and reflex contraction of muscle?

A

Activation of alpha and gamma motor neurons

46
Q

Gamma bias

A

Presenting of gamma activity as voluntary motor activity begins

47
Q

What is gamma bias based on?

A

Prediction by motor centers as to how rapidly and how much muscle length will change with the activity

48
Q

How gamma bias works with higher centers

A

As information comes in informing motor control centers about what is going on, this is compared to the predictions, and if there is a difference, corrections are made as movement proceeds

49
Q

There is always some level of tone in muscle. What is it maintained by?

A

Partly maintained by gamma neurons

50
Q

What does constant level of gamma tone allow for?

A

Constant flow of info about muscle length

51
Q

High tone

A

Excessive gamma bias

52
Q

Low ton

A

Abnormally low gamma bias

53
Q

What happens to gamma activity with neurological injury?

A

Balance between facilitation and inhibition of gamma activity is upset

54
Q

Where are Golgi tendon organs found?

A

In tendons of all skeletal muscles

55
Q

What des GTO monitor?

A

Muscle tension

56
Q

What type of afferent nerve carries info from GTO

A

1b fibers (myelinated, slightly smaller than 1a)

57
Q

Where are the sensory endings located in the GTO

A

Intertwined among the collagen fibrils

58
Q

How does GTO measure tension?

A

Muscle contracts

Tension transmitted through collagen fibrils, which stimulates the specialized sensory endings

59
Q

Golgi tendon organ reflex AKA

A

Inverse Myotatic reflex

60
Q

Function of GTO

A

Thought to be important in protecting tendons from injury…

Fater’s opinion: role is to keep higher motor centers informed about the degree of muscle tension developed

61
Q

Pathway of nerve signal in GTO response

A 
Same as flexor withdrawal, except the afferent nerve is a 1b fiber
In affected leg:
Quads inhibited
Hamstrings activated
In unaffected leg:
Quads activated
Hamstrings inhibited

Physiology (17 decks)

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