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A&P 2024 > Lecture 14 - neuro reflex > Flashcards

Lecture 14 - neuro reflex Flashcards

Exam 3

1
Q

Which reflex(s) cross the cord?

A

crossed-extensor

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2
Q

Which reflex purpose is to keep muscles at a constant length, weight-bearing support?

A

Stetch/ muscle spindle

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3
Q

Which reflex serves to cease muscle contraction under heavy load to prevent muscle from tearing off bone?

A

Tendon

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4
Q

which reflex serves to withdraw limbs from painful stimuli to prevent injury

A

Withdrawal/Flexor

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5
Q

Which reflexes involve multiple levels of the spinal cord above and below?

A

Pain reflexes:
Withdrawal/Flexor and Crossed-extensor

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6
Q

Where are the ascending and descending interneurons located?

A

Located in the white matter of dorsal border of dorsal horn = “Tract of Lissauer”

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7
Q

Which variation of nACh-Receptors are located only at the NMJ?

A

mature/adult

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8
Q

Which variation of nACh-Receptors can be located outside of the NMJ?

A

Immature/”fetal nACH-R”

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9
Q

Which variation of nACh-Receptors are comprised of 5 alpha domains? where is it located in the body?

A

alpha 7, CNS

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10
Q

Which type of nACh-R is comprised of
2 alpha binding domains
1 epsilon
1 beta1
1 delta

A

mature/adult

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11
Q

Which type of nACh-R is comprised of
2 alpha binding domains
1 gamma
1 beta1
1 delta

A

immature/”fetal”

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12
Q

Which nACh-R has high conductance?

A

mature/adult

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13
Q

Which nACh-R has low conductance?

A

immature/fetal

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14
Q

What does it mean if a channel has “high conductance”?

A

when open, the speed that ions move through the channel is high. They close faster as well.

low conductance= lower speed

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15
Q

Which nACh-R is worse for succinylcholine to bind to, resulting in much higher levels of K+ leakage?

A

immature/fetal

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16
Q

What are the 4 reflex pathways?

A

Stretch
Tendon
Withdrawal
Crossed Extensor

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17
Q

An _______ is a bridge between a sensory neuron and a motor neuron

A

Interneuron - can also allow cross-over

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18
Q

Are interneurons excitatory or inhibitory?

A

Can be either

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19
Q

Do interneurons travel vertically or horizontally?

A

Can be either

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20
Q

Stretch reflex usually ______ have interneurons and ______ cross the cord

A

doesn’t and doesn’t

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21
Q

What is the purpose of interneurons in the stretch reflex if they are present?

A

Inhibitory interneurons that allow reflex relaxation of the antagonistic muscle set

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22
Q

Which reflex is responsible for maintaining posture?

A

Stretch

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23
Q

What are the springs called that sense how much tension is in the muscle for the stretch reflex?

A

Muscle spindle = stretch receptor

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24
Q

Differentiate between a direct reflex arc and a secondary reflex arc

A

Direct reflex arc:
- Stretch-Contract
- Contract effector (quadriceps, eg)

Secondary reflex arc:
- Inhibitory interneuron
- Inhibit antagonist muscles (hamstring, eg)

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25
Q

What are the sensors that detect tension of tendons on muscles for the tendon reflex?

A

golgi tendon sensors

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26
Q

What are the two reflexes of the tendon reflex?

A

Reflex #1: Cease (inhibit) contraction under heavy load to prevent tendon tears
Reflex #2: Contract (excite) antagonistic muscles to speed retraction from load source

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27
Q

Flexor reflex alternate name

A

Withdrawal reflex

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28
Q

Which pain reflex is used when static vs moving?

A

Flexor - static
Crossed extensor - moving

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29
Q

What are the two reflexes of the crossed extensor reflex?

A

Reflex #1: Several levels of left “hamstring” flexor motor output from spinal cord. Withdraws left leg from painful stimuli.

Reflex #2: Several levels of right “quad” extensor motor output from spinal cord. Assures that we have good footing to use as a push-off point for #1 above.

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30
Q

What are the simplest vs most complicated reflexes?

A

Simplest - stretch
Most complicated - crossed extensor

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31
Q

Pain receptors synapse on _______ in grey matter.

A

2nd-order interneurons

32
Q

How can you determine depth of a block with reflexes?

A

Reflex not present - block deeper

33
Q

If the nervous system doesn’t get information back from muscle that contraction occurred, the body’s response is to?

A

Put more ACh-R at the NMJ
- Also end up on places other than NMJ (entire muscle)
- Fetal nACh-R instead of mature

34
Q

ACh-R found in the NMJ are called _____

A

junctional

35
Q

ACh-R found in the borders of the NMJ are called _____

A

peri-junctional

36
Q

ACh-R found away from the NMJ are called _____

A

post-junctional

37
Q

_________ is a strong enough voltage to allow depolarization to generate an AP in the underlying neurons

A

Supramaximal stimulus - voltage that is strong enough stimulus to recruit all motor neurons/skeletal muscles

38
Q

TOF stimulation Hz/seconds

A

2 Hz over 2 seconds = 4 twitches

39
Q

Repetitive, high frequency stimulation for a short period of time

A

Tetanic contraction

40
Q

_________ - impulses after tetanic contraction

A

Post-tetanic count (PTC)

41
Q

What kind of nerve stimulation shows the health of a synapse?

A

Post-tetanic count (PTC)

42
Q

A _______ is a series of tetanic contractions

A

DBS: Double-burst stimulation

43
Q

The ulnar nerve innervates the ______ muscle

A

Adductor Pollicis

44
Q

What happens with contraction of the Adductor Pollicis muscle?

A

thumb comes forward and/or pinky twitches

45
Q

What are the alternatives to neuromuscular monitoring in muscles other than the Adductor Pollicis?

A
  • Ophthalmic branch of Facial nerve
  • Peroneal nerve
  • Posterior tibial nerve
46
Q

A _______ is a graphical depiction of underlying muscle activity to determine response

A

EMG

47
Q

What are the 3 ways to of neuromuscular monitoring?

A

Velocity meters
EMG
Visual assessment

48
Q

How quickly does sux begin to wear off?

A

3 min

49
Q

Differentiate between TOF stimulation of a NDMR vs Sux

A

NDMR: first contraction is the strongest (A), last contraction is the weakest (B)
Sux: equal strength of contractions

50
Q

What is the TOF ratio?

A

B/A
- Weakest contraction/strongest contraction
- only works for NDMR
- need all 4 stimuli to measure

51
Q

The Sux TOF ratio is always ___

A

1

52
Q

As the NDMR wears off, the TOF ratio does what?

A

Gets closer to 1

53
Q

Why are the contractions of the NDMR unequal, while the Sux contractions are equal?

A

muscle relaxants act on the motor neuron and the skeletal muscle
- autoreceptors reduce amount of ACh being released from the motor neuron due to ion current (VP-1 to VP-2)
- NDMR contractions differ because Sux primarily works on the skeletal muscle, not the motor neuron

54
Q

What is the makeup of autoreceptors?

A

3 alpha
2 beta

55
Q

What determines transition of VP-1 vesicles to VP-2?

A
  • autoreceptors on the motor neuron ion current
56
Q

The more important a muscle is, the more ______ it is to polarize

A

difficult - more robust NMJ (more receptors)

57
Q

What spinal level does the phrenic nerve connect to the diaphragm?

A

C3-C5

58
Q

The _______ is a skeletal muscle that separates the abdominal cavity from the thoracic cavity

A

diaphragm

59
Q

What nerve connects C3-C5 to the diaphragm?

A

The phrenic nerve

60
Q

4th Twitch Disappears: ____% nACh-R’s blocked

A

~75-80%

61
Q

3rd Twitch Disappears: ____% nACh-R’s blocked

A

85

62
Q

2nd Twitch Disappears: ____% nACh-R’s blocked

A

~85-90%

63
Q

All Twitches Disappear when ____% nACh-R’s blocked

A

~90-95

64
Q

How high can a spinal nerve injury be and still be able to ventilate?

A

C4

65
Q

Would the diaphragm or the adductor pollicis muscle recover first from a paralytic?

A

Diaphragm

66
Q

A patient who is able to lift their head has ____% nACh-R’s blocked

A

70

67
Q

A patient can probably breath on their own when there are ____ twitches present on the TOF

A

all 4

68
Q

What is the normal setting for TOF?

A

50-80 mA - curent

69
Q

What are the 3 ways K+ is lost when Sux is bound to ACh-R?

A
  1. leak channels
  2. V-G K+ channel
  3. K+ loss through ACh-R
70
Q

Which muscle is controlled by multiple motor neurons?

A

occular muscle in eye socket

71
Q

If you give sux to the skeletal muscle in the eye socket, what would you expect to happen?

A

Since multiple motor neurons control the muscle, you would expect increased IOP (increased Ca++ entry), putting stress on optic nerve - potential blindness

72
Q

What are the 2 most important inhibitory NTs in the spinal cord?

A

GABA and glycine

73
Q

What are the 3 NT that increase CNS activity?

A

Histamine, glutamate, NE

74
Q

How does dopamine effect the CNS? Which disease is caused by decreased dopamine production?

A

Inhibits motor activity; Parkinson’s (overactive motor system)

75
Q

How does acid base balance effect CNS activity?

A

Acidosis → increased free Ca++ → reduced CNS activity
Alkalosis → decreased free Ca++ → increased CNS activity

A&P 2024 (19 decks)

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